Figure 15.2 The Night-time View of the Eastern United States, as Seen from Space2603

The thermal burden of energy usage on Earth is a planetary, not local, issue.

A primitive intelligent alien race, slowly evolving and spreading across the face of its native world, eventually will discover and utilize a wide variety of elementary energy supplies. In the beginning, such creatures would rely mainly on natural sources such as hot springs, fires set by lightning, and their own muscle power.

But soon their intelligence, and the Principle of Economy, would impel them to develop new and easier ways to generate and harness energy. They‘d learn to set their own fires, and how to control them. Animals might be harnessed for transportation, hauling, and agricultural activities. Better fuels, such as coal or natural oil secured from local tar pits, would replace wood in campfires.

On our own home planet, this early period was marked by a relatively slow growth in worldwide energy usage. The increase amounted to no more than perhaps 0.3% per year, a doubling time of about 200 years. The speed at which basic resources could be pressed into service, with primitive technology and finite manpower, was extremely limited. Such an early "incubation period" of leisurely growth should be common during the first stages of cultural evolution on any world.

It is entirely possible that ETs on some planets may call a halt, or even reverse, this upward trend in energy consumption. This does not necessarily imply an immediate halt to all technological development — for instance, the culture may simply be shifting its attention from energy-intensive projects to information-intensive ones. However, it does place rather stringent limitations upon the material achievements to which the society may aspire. Without abundant energy, an economy of scarcity management is virtually inevitable.

Finding this prospect rather unattractive, and driven onward by the curiosity and aggressiveness that enabled them to take dominion over their world, many intelligent extraterrestrial races would seek to further improve both the sources and the distribution of power.

On Earth, the widespread initiation of fossil fuel burning (stored solar energy) provided a powerful new source of abundant energy. While great effort was required to harvest tiny amounts of power from wind and water, a tiny bit of oil or natural gas went a long way. In addition, steam and electricity came into their own during the last two centuries of human history. There was getting to be an abundance of raw energy, powerful ways of harnessing it to perform useful work, and efficient means of transmitting it over great distances. The dawn of global culture was at hand (Figure 15.2).

In the last two centuries, humanity has maintained a 3% per year growth rate in energy consumption, a full order of magnitude above the early stages of cultural evolution on Earth. The doubling time is now measured in decades rather than in centuries. Let's see exactly what this means.

It is believed that the Roman Empire, at the height of its expansive construction and military activities, annually consumed power at a rate roughly equivalent to 3 × 10⁹ watts (1 watt = 1 joule/second). Nearly two millenia later, humanity has increased its energy usage a thousandfold. By 1975, global power consumption reached about 7 × 10¹² watts. In only two thousand years, mankind's per capita energy production has leapt from about 30 watts/person in ancient times to nearly 2000 watts/person today.

Xenologists want to know whether or not energy usage will also increase exponentially among alien cultures, as it appears to have done here. Perhaps more interesting and germaine, however, is the following related query: Are there any limits to growth, assuming the ETs adopt an expansionist philosophy?

It turns out, not surprisingly perhaps, that there do exist very definite limits to growth for any culture that remains confined to the surface of a single planet. There are three fundamental factors which delimit the quantities of energy accessible to a sentient race:

• Availability
• Efficiency
• Planetary carrying capacity

Our first consideration is the availability of a given energy resource. In general, sources compete with one another depending on their relative scarcity or abundance. To take one trivial example, an alien culture located on a world with little water and strong winds might be expected to place greater emphasis on the development of windmills rather than waterwheels or dams.

A corollary to the fact that a civilization is planetbound is the inevitable finiteness of all resources. There is only so much wind, water, geothermal steam, wood, fossil and nuclear fuels at the surface of a world. Once the population of an extraterrestrial culture has expanded to the point where these resources are in danger of exhaustion, the civilization faces drastic modification, degeneration, or possibly even extinction on a global scale. Such is the early and quite predictable result of sole reliance upon nonrenewable sources of energy.

Fortunately, there exist two sources which should be available to all ET societies and which are virtually inexhaustible. First, there is nuclear fusion. This involves mashing together two atoms (usually of hydrogen) which yields a single heavier atom plus lots of energy. About one hydrogen in every 6000 in ordinary seawater is deuterium, the most likely hydrogen isotope to be used in controlled thermonuclear power generation. It is estimated that if all the deuterium in Earth's seas were collected and burned in fusion power stations, it would supply all our energy needs at the present rate of consumption for the next 5-10 billion years — roughly the expected lifetime of Sol.

An alien civilization that opts for fusion power may expect to have enough energy to endure over geological timescales provided there is no growth. If there are oceans of water sufficient to spawn life, there will probably also be enough deuterium to provide all "Type I"* planetbound cultures with virtually inexhaustible energy.**

The other major energy source available to planetary cultures is solar power. Unless blocked by a thick cloud cover, filtered out by the atmosphere, or attenuated by great distances, radiative energy from the stellar primary can serve as a bountiful and virtually infinite "renewable" source of power. Since stars in habitable solar systems may be expected to have lifetimes measured in eons, a Type I extraterrestrial civilization could again expect a long healthy existence before its energy supply ran out.

So on the question of availability, a large-scale Type I planetary culture should ultimately benefit most from either deuterium fusion power or solar fusion power.

* Dr. N.S. Kardashev, a well-known Russian astrophysicist currently associated with the Institute for Cosmic Research at the Soviet Academy of Sciences in Moscow, devised a particularly fruitful classification scheme which includes all conceivable ET civilizations and is based on system-wide energy consumption.¹³²⁰ However, Kardashev limited his analysis to the energy available for the purpose of interstellar communication between alien cultures. In this book the original concepts are broadened to provide a general taxonomy for all extra-terrestrial civilizations — whether communicative or not.

** Cultures native to planets with ammonia or methane oceans similarly will have an abundance of deuterium fusion fuel at their disposal. Inhabitants of worlds with sulfur or liquid carbon dioxide seas will not be so fortunate.

Table 15.1 Conversion of Matter into Energy: A Comparison of Efficiencies

The second consideration involves the question of the efficiency of the particular energy resource chosen. Since the technology of a civilization limited to the surface of a single world will ultimately experience severe restrictions on its finite resources, it is important to make the best use possible of what little is available.

Earlier in this century, the late Albert Einstein demonstrated that mass and energy are interchangeable. According to the famous E = mc², a given amount of matter (m) is exactly equivalent to a certain quantity of energy (E). (The constant of proportionality, c², is the speed of light, squared.) All energy, whether from fusion, fission, or chemical reactions, ultimately derives from the conversion of a tiny bit of matter into heat, light, sound, etc.

If their civilization is to long endure, ETs must find the most efficient means for converting mass into energy. Table 15-l provides a representative sampling of various common and theoretical energy sources available to Type I planetary cultures on any world in our Galaxy. In each case the efficiency is calculated, based on the fraction of matter which is changed into usable energy. The most efficient is "total conversion" (100% of the matter goes to energy), but it is difficult to imagine the cheap production of sufficient quantities of antimatter to make this process competitive with thermonuclear fusion.

Indeed, fusion appears to be the most efficient energy generation technique for which the fuel is exceedingly abundant. Once again, both deuterium fusion power and solar fusion power qualify as most efficient. So on the basis of the two factors we‘ve looked at, it is a pretty sure bet that advanced Type I alien cultures will adopt either or both of these techniques.

Figure 15.3 Curve of Growth of Technological Energy Usage for a Typical Emergent Type I Civilization: Humanity Full Size

But even using the most efficient, abundant sources of energy, planetbound societies cannot continue to expand indefinitely. This is because of the third critical limiting factor: Planetary carrying capacity. The history of our own planet is typical.

In the past century, world energy production has escalated at an average rate of 3% per annum. Approximately every twenty years, human power consumption doubles. In 1975 we used 7 × 10¹² watts. If the historical 3% growth rate is maintained, then by the year 2300 A.D., mankind's energy budget will be up to 2 × 10¹⁷ watts. Why is this significant? Simply because 2 × 10¹⁷ watts is also the total power received from Sol on planet Earth. To sum up, by 2300 A.D. humanity will be generating as much energy artificially as is received at the planet's surface from its sun (Figure 15.3).

We will then face the most critical "energy crisis" in the history of Earth. Rather than a crisis of scarcity, however, it will be a crisis of overabundance.

All forms of energy — electrical, thermal, mechanical, nuclear — ultimately return to the biosphere in a single degraded form: Heat. Such thermal pollution can rapidly reach catastrophic proportions. As more and more energy — heat — is liberated at the planetary surface, the global temperature begins to rise and the precarious energy balance of the biosphere begins to suffer irreversible damage.

At what point in the development of a Type I civilization will this ultimate "hypsithermal catastrophe" occur? Certainly by the time artificial energy production equals total solar influx, the planet will have suffered serious ecological damage.²⁹ Earth, for instance, would no longer be inhabitable by humans, our lush green world converted into a stewing, steamy hellhole much like Venus. Most experts believe that irreversible destruction of environmental equilibrium would occur at far lower levels of energy production. Conservatives usually draw the line at the photosynthetic energy limit, or the total solar energy fixed by green plants worldwide. This is only about 4 × 10¹³ watts.

The best guess seems to be about 1% of the total solar influx as the critical limit.^{29, 688} This is about 5% of the energy stored in Earth's hydrosphere, and would probably be sufficient to melt the polar icecaps and thoroughly disrupt the entire ecology. On planets with smaller oceans, or with non-water oceans, the climatic turnover point might occur far sooner.

We estimate, therefore, that the maximum upper limit of artificial energy generation for any Type I planetary culture limited to a single world in our Galaxy is roughly 10¹⁵ watts.

Biological engineering — "bioneering" for short — is the technology of genetic engineering. While the nucleic acids represent the blueprints for all Earthly organisms, the biochemical specifics may vary from world to world. Still, the general principle of manipulating the executive molecules of life — whatever they are — should be more or less universal.

Xenobiologists today believe that it will soon be possible to: splice, repair, recombine, synthesize, and transplant specific terrestrial genes and chromosomal patterns between individuals and even between species. What humanity will probably achieve in the coming century may already be well-known to countless advanced extraterrestrial bioneers as well.

People have long been astounded by the feats of so-called "human calculating machines." An 18th-century Englishman named Jedediah Buxton reputedly could multiply three 6-digit numbers in his head almost instantly, but his mind was otherwise dull and he remained a day laborer all his life. Zerah Colburn, a rather shy Vermontian born in 1804, attracted even more attention as a child by solving involved mathematical problems.

Taken to London at the age of eight, he gave math professors instantaneous answers to such questions as raising 8 to the 16th power and extracting the cube root of 268,336,125. Another mental marvel, Johann Martin Dase, was born in Hamburg, Germany in 1824. Dase once correctly multiplied together two 100-digit numbers in his head in only nine minutes.

Since there really was nothing unusual about the upbringing of any of these individuals, the simplest explanation is that their abilities were congenital in origin. Through some odd shuffling of the genetic deck, some gene or sequence of genes produced a brain of incredible calculational capability rivaling at least that of early-generation electronic computers. If ETs encouraged the spread of some similar hereditary pattern throughout their own gene pools, their entire population could become a race of arithmetic wizards.

Other aspects of intelligence similarly may be upgraded. One well-known case of fantastic memory was Elijah of Vilna, a Lithuanian rabbi, who during his lifetime read more than two thousand treatises. He could recall any sentence on any page in any book at will, without error, and was unable to forget anything he’d read — an ability the rabbi regarded as a curse.

His memory represented a storage capacity of at least five billion bits of information — again, a capacity comparable to the large magnetic disk memory units used in modern computers.

It is entirely possible that aliens, by judiciously selecting specific constellations of genes, could arrange to give themselves and their offspring total-recall eidetic memories, fast arithmetic ability, and a host of other genius-level mental qualities.

In a series of experiments, Dr. Allen L. Jacobson of the University of California showed that RNA functions as a carrier of memory in the mammalian brain. Jacobson taught rats and hamsters to retreat into a feeding box at the flash of a light or the sound of a click. The conditioned animals were sacrificed and the RNA carefully extracted from their brains.

This material was then injected into untrained animals of the same species, who subsequently proved far easier to train than their predecessors. One unexpected finding was that the transfer of learning worked cross-species: Untrained rats benefited from injections of trained-hamster RNA.

If these results can be confirmed, the implications of such "memory molecules" are staggering. Injected directly into the bloodstream, synthetic viruses consisting of nothing more than a central core of nucleic acid (commonly RNA) surrounded by a sheath of protein could be used to "infect" a brain with knowledge. Remarks one writer:

We would be able to learn French, or algebra, or anything else whose code we knew, by injection. One can imagine education by mass inoculation, or the use of bacteriological warfare techniques for beneficent purposes by spraying entire populations with "good" viruses. The teaching of many subjects would become obsolete).¹⁸⁶⁰

Drs. Alexandre Monnier and Paul Laget, French geneticists, have suggested that these coded forms of knowledge be written directly onto the original genetic specifications. Like the social insects, who carry a plethora of pre-programmed knowledge in their genes, humans of the future or extraterrestrials of other planets might be able to arrange to be "born smart." Each infant could carry the genes to manufacture RNA information equivalent to several university doctoral degrees. Much basic knowledge — the ability to walk, to speak in many tongues, to swim and dive, to pilot a spacecraft, to perform intricate mathematical calculations using established techniques, to play a piano — could be incorporated directly into the nucleus of the fertilized egg so that the organism would possess all these abilities without ever having to learn them.

The evolution of physically larger brains by deliberate breeding and selective gene transplantation is another practical option for ETs seeking intelligence amplification. "Is it very rash," asks Dr. Jean Rostand, "to imagine that it would be possible to increase the number of brain cells?" His answer:

A young [human] embryo has already in the cerebral cortex the nine billion pyramidal cells which will condition its mental activity during the whole of its life. This number, which is reached by geometric progression or simple doubling, after 33 divisions of each cell (2, 4, 8, 16, 32, and so on), could in turn be doubled if we succeeded in causing just one more division — the 34th.²⁶⁴⁵

Many neurologists remain skeptical of such suggestions, claiming that normal birth would be quite impossible with a head so large. According to Dr. H. Chandler Elliot:

The man of the future was depicted by early fantasy writers with a huge head to house a superbrain; but this picture is discarded by modern sophisticated science fiction as naive and implausible, even for inhabitants of other worlds.⁹⁰

But as Rostand has pointed out, the supercranial fetus could be produced in an artificial womb. Since the opening could be made as large as required, the impossible-birth consideration is largely irrelevant.

It is impossible to rule out the possibility of genetically amplified, bioneered aliens, possessing memory, mental acuity and speed of thought comparable to some of the finest computers available on Earth today.

"Genetic surgery" is a term used to describe the manipulation of DNA and RNA — the executive molecules of terrestrial life — for specific purposes. Many scientists believe that in the near future human biotechnology will be able to "delete undesirable genes, insert others, and mechanically or chemically transform others."⁹²

The methods of genetic surgery will often require the deft insertion of new genes into the nuclei of malfunctioning cells. This is called a "gene transplant," a technique already proven by tests involving human subjects. In one early experiment conducted by Carl Merril, Mark Grier, and John Petriccione at the National Institutes of Health in Bethesda, Maryland, specially prepared virus were used to carry DNA into cultured cells taken from people suffering from galactosemia (an enzyme-deficiency disease). After the viruses and the human cells were mixed together in solution and warmed to normal body temperature, the researchers found that the cells had absorbed a gene which had been placed in the virus that was capable of repairing the deficiency. The transplant complete, the cells began to manufacture the previously deficient enzyme in adequate quantities.

In 1970, Dr. Stanfield Rogers, a medical geneticist at the Oak Ridge National Laboratory in Tennessee, performed one of the first experiments on human subjects. A group of children had a rather rare genetic disease called Argininemia, a congenital disability to produce an important enzyme called arginase because of defects in the chromosomal DNA. Rogers selected a microorganism called Shope virus which, while harmless to humans, causes the cells it invades to produce an excess of arginase. A few months after the young children were injected with Shope virus, their bodies began producing the needed enzyme — proof that the viral treatment was beginning to work. The foreign arginase-producing genes had been transplanted into some of the children’s cells.²³⁶⁵

Genetic surgery and transplantation biotechnology may give ETs the ability to regenerate lost limbs or damaged organs. Each cell contains all of the organism’s genetic information, but most of it is suppressed because of specialization as a nerve cell, liver cell, or brain cell. If the expression of these hidden parts of the gene package can be unblocked, new limbs and organs could be grown by stimulating the correct genome sequences at the right locations. Nerves might be regenerated, eyeballs repaired, arms and legs regrown from scratch.

Similar techniques could possible minor modifications in physical appearance — such as skin or hair color change — or major modifications in body form such as extra arms, fingers, or special organs. The degree of genetic individuality may be so great among extraterrestrial bioneering races that each organism might represent his own distinct and unique "species."

Where will participative evolution lead? Eventually ETs, as man, will no longer be satisfied merely with correcting errors and improving upon the old models. Rather, they will have the urge to go nature one better, to create new synthetic organisms for specialized purposes.

Dr. Paul Berg of Stanford University (one of the first scientists to perform "recombinant DNA" experiments) in 1973 mixed together fragments of a bacterial "plasmid" (tiny circlets of DNA imparting resistance to antibiotics) with genes from a virus that produces cancerous virus in monkeys, in a single test tube. These combination virus-plasmids were then allowed to invade normal E. coli bacteria, which soon began churning out viral protein. Using simple gene splicing, Dr. Berg had created a "genetic hybrid" organism — a cross between a cancer-producing virus and a bacterium — which had never before existed in nature. The methodology, says Berg, "is simple and can probably be done as a high school science experiment."²³⁶⁵

Since 1973, scientists have used plasmids to introduce mouse and frog DNA into bacterial cells. It appears quite possible to create hybridized plants and animals, beings not found in nature.* It would be, as one participant at the 1976 Asilomar Conference on recombinant research jokingly put it, "like crossing an orange with a duck."

Much as man learned long ago to domesticate and cultivate the lifeforms of his world, sentient bioneering races will learn to exploit the gene as well for their own purposes.

As regards most biochemical substances, mankind is still in the "food gathering" stage. Many needed hormones, such as insulin, must be laboriously collected from scores of individual animal organs. But this situation has begun to change in the last few years.

Scientists have succeeded in transplanting a gene for rat insulin into bacterial cells which is reproduced when the cells divide, and it will soon be possible to switch the gene on as well. By cultivating insulin-making DNA, keeping it supplied with the raw materials and energy it needs, hybridized cells can be harvested for hormones much as a farmer reaps a field of wheat.

Along these lines, Drs. Herbert Boyer, Arthur Riggs, and Wylie Vale spliced the gene for somatostatin into the DNA of E. coli bacteria. Somatostatin is a hormone in the brains of mammals that inhibits the secretion of pituitary growth hormone. The hybridized bacteria multiplied and began producing somatostatin in copious quantities. Before, nearly half a million sheep brains were needed to isolate 5 milligrams of somatostatin. Using the E. coli "hormone factory," scientists required only 8 liters of bacterial culture to obtain the same amount.

The key to genetic cultivation is the synthetic gene — artificial nucleic acid sequences that have never occurred in nature. The first total synthesis of a complete gene starting from scratch was first accomplished by Nobelist Har Gobind Khorana and his team at MIT. The experiment involved the re-creation of a "tyrosine transfer RNA gene" found in E. coli which is 207 nucleotide base pairs in length. While it took the MIT group nearly a decade to do it, they are confident that genes as complex as those of humans (1000-3000 nucleotide base pairs long) will be amenable to synthesis in the next fifty years.²⁶⁴⁶ It is then a relatively simple step to the production of "unnatural" genes.

With the ability to create artificial genomes with specific desired characteristics, alien bioneers can better exploit the whole animal kingdom. Domesticated beasts with augmented intelligence and specially modified limbs and organs might function as excellent animal servants. Genetically altered horses might be used as intelligent, self-steering, self-feeding, self-cleaning, self-reproducing personal transport vehicles. Arthur C. Clarke points out that something resembling a compact elephant might be preferable in this regard, since it is the only quadruped with sufficient dexterity to carry out delicate handling operations while remaining a quadruped.⁵⁵ Such animal slaves should be herbivorous because "carnivores are much too expensive to feed and might take a fancy to their riders."

Lesser lifeforms may be pressed into service by ETs. Genetically upgraded birds could be used as aerial messengers and scouts, and would be trained to speak some simple language. Traitor fish could be developed to steer schools of their unsuspecting fellows into the waiting nets of fishermen. Vicious insects, giant crustaceans and monstrous mollusks could be bred as offensive weapons of tactical warfare.

Freeman J. Dyson of the Institute for Advanced Study at Princeton University has suggested the possibility of exotic, genetically-modified artificial mining organisms, trolling the seas of planets for valuable minerals and metals. Says Dyson:

Oysters might extract gold from seawater and secrete golden pearls. A less poetic but more practical possibility is the artificial coral that builds a reef rich in copper or magnesium. Other mining organisms would burrow like earthworms into mud and clay, concentrating in their bodies the ores of aluminum or tin or iron, and excreting the ores in some manner convenient for human harvesting.²⁷

At least one mining company already uses bacteria to help recover copper metal from a variety of low-grade ores.⁸⁸

The extraterrestrial bioneers may themselves be the subjects of genetic modification. Instead of creating expensive, cumbersome artificial environments to sustain their lives after planetfall, ETs may decide to undergo a change in basic physical form enabling them to survive the natural conditions encountered on each new world. Conforming to the alien environment should facilitate both exploration and first contact, should it occur, with sentient natives.²⁶⁵¹

Advanced xenobiotechnology will allow extraterrestrial astronauts to decide which form was most convenient. Should they wish to explore and inhabit Jupiter for a period of time, for example, they could infect themselves with a carefully tailored virus containing modified genetic material. Cells in their bodies would be taken over by the intruders. Some would metamorphose into, say, jovian "gasbag beasts," while the rest would simply die away and be sloughed off like molted skin. Later, the gasbag genes might be replaced with new ones coded to produce a large-chested surface creature capable of breathing the 0.1% oxygen atmosphere of Mars. Finally, their survey completed, the ETs would be returned to their normal spacefaring designs using yet another application of a different transmutation virus — perhaps a small, agile humanoid form with a dexterous prehensile tail and a high tolerance for conditions of low gravity and sudden atmospheric decompressions.

When first contact with extraterrestrials occurs, we won’t know if the aliens are truly as they appear or rather inhabit genetically doctored bodies. Perhaps those tan-skinned humanoids we just shook hands with are really a race of chlorine breathers with twelve greasy tentacles and porcupine-bristled fur.

* In 1976, researchers at Florida Atlantic University at Boca Baton created the first "interkingdom protoplast" which they call the "plantimal."¹⁶¹⁷ Joined were a human cell nucleus and a tobacco cell nucleus, and, in another experiment, a human nucleus and a carrot nucleus. Extraterrestrial bioneers may have developed photosynthetic meatlike "blobs" to serve as protein livestock, shapeless amorphs which convert sunlight directly into edible meaty material. Autotrophic animals such as "plant men" similarly may be possible.

Ectogenesis is the process of "test tube pregnancy" as exemplified by Aldous Huxley’s science fiction classic Brave New World.  If an artificial placenta can be designed, complete artificial development of an entire human being will be possible starting only with sperm and egg. As long ago as 1959, a plastic womb designed by Italian surgeon and medical experimentalist Daniele Petrucci carried developing human embryos for nearly two full months. There are recent reports that the first human test tube birth has already taken place,²⁸⁷¹ although these are discounted by most reputable scientists.²⁸⁷²

Aside from using ectogenetic techniques to control birth rates or maintain rigid biological castes, aliens might find test tube birth an ideal solution to the problem of interstellar colonization. Instead of keeping adult ET travelers in suspended animation for hundreds of years in transit between stars, compact frozen embryos could be dispatched to the target solar systems. Upon arrival, these ectogenetic astronauts would be fertilized and carried to term in an artificial womb. At birth, cybernetic devices or RNA memory molecules could be used to teach the infants about their culture, their science, and their mission. The starship would then enter orbit around the new world and finally land, the now-adult alien colonists emerging to begin life on foreign soil.

Cloning is a related biotechnology that ETs will probably have. It’s a form of genetic engineering by which many exact duplicates of the original organism may be produced. Except for blood corpuscles, every cell in the mammalian body has identical and complete sets of genes which uniquely specify the entire organism. The nucleus from a human skin cell transplanted into an ovum and carried to term ectogenetically should produce an exact twin of the original donor. In 1969, Dr. John B. Gurdon at Oxford University succeeded in creating countless cloned frogs by transplanting genes from adult frog cells into the nuclei of frogs’ eggs.

Aliens will find many interesting uses for cloning. According to technologist Robert W. Prehoda, a combination of cloning and cryobiology (low-temperature preservation) could permit useful plants and animals to be conveniently transported with interstellar colonizers to make it easier to quickly populate barren planets with the flora and fauna of home.⁶⁷ Cloning may also allow alien plants and animals to be reproduced in great numbers back on the home world, after interstellar expeditions across the Galaxy return with frozen cell samples of exotic foreign lifeforms. Extraterrestrial bioneers may also clone duplicates of themselves as successors in political office,¹⁹⁴⁷ as standardized military units, or as nonsentient living warehouses for biological spare body parts for organ transplantation operations.

The basic survival instinct must be very deeply ingrained in many alien races. This, in concert with a sophisticated biotechnology, provides both motive and opportunity for the development of immortality among extraterrestrial civilizations.

Recalling Medawar’s assertion about human nature cited earlier, can we be as certain that aliens too "would rather be alive than dead"?

Maybe not. Consider the alternative forms of sentience discussed in {tip content="Reference: 14.2 Juvenile Extraterrestrial Intelligences
Paragraph #8, Begins: From these three curves,"}Chapter 14{/tip}. Beings with genetic sentience — "intelligent ants" — may harbor no desire for personal immortality whatsoever. Since they aren’t aware of their individual selves, they could never sympathize with Ionesco’s very human lament: "Why was I born if it wasn’t forever?" Since the society of these creatures would be virtually immortal, genetic-sentient ETs may have no use for the concept of (effectively) perpetual personal existence.

Similarly, beings with communal sentience (visceral social awareness) may be able to take solace in the comparatively eternal character of society. It may be that the appetite for immortality displayed by many humans is a hunger unique to brain-sentient species. Only among these races must the individual deal with personal death in the absence of any strongly-felt, well-internalized and supportive societal framework.

Of course, even among brain-sentient extraterrestrial species there may be cultural, psychological, or biological reasons why the drive for immortality might be suppressed. Yet the basic survival instinct must be very deeply ingrained in many alien races. This, in concert with a sophisticated biotechnology, provides both motive and opportunity for the development of immortality among extraterrestrial civilizations.

Brain cells do not reproduce and cannot replace themselves once destroyed. Each human possesses ten billion irreplaceable neurons; when some are lost due to concussion, consumption of alcohol or tobacco, or from natural causes, our brains are permanently diminished.

Dr. Harold Brody of the State University of New York at Buffalo attempted to measure the rate of natural attrition of brain cells. While losses range from none at all to very many in various parts of the organ, the approximate brainwide average runs about 100,000 neurons lost per day. At this rate, Brody calculates, the organ should entirely decay away in a period of about 250-350 years.²⁶⁴⁸ Whether cell loss would actually continue to the vanishing point or would taper off asymptotically is unknown at present.

There are at least three solutions to the so-called "brain barrier" problem. First, genetic engineering could permit each individual to start out with a larger brain. If the ETs have 100 billion neurons — ten times more than we — and the same neural attrition rate, senility might not set in for thousands, instead of hundreds, of years. The full millenium of Stage 3 aging would then become available to the aliens.

A second solution is to cause brain cells to regenerate and reproduce them selves as others died. If neuron division could be exactly balanced against cell losses, the brain would remain the same size and theoretically could go on forever. This again will only be found among extraterrestrial races capable of advanced bioneering, since there is no natural selective value in developing complex brain regeneration mechanisms which aid survival only if the organism manages to pass the primary and secondary self-destruct systems of the body. What if aliens did have divisible brain cells? In his book The Immortality Factor, Osborn Segerberg, Jr. writes:

[Brain cells] store our memories, experiences, knowledge and learning as well as operate voluntary and autonomic nervous systems. New brain and nerve cells presumably would "forget" what their predecessors knew. If the [being] survived the neurological havoc, he might not be able to retain his identity. He would forever be turning into someone else.⁶⁹

Or, as another writer puts it: "What would be the fun of attaining great longevity if the lucky winner couldn't remember what had gone before?"²¹³⁷

Of course, the counterargument goes like this: We know we lose 100,000 neurons every day. If this causes personality change from day to day, we certainly do not notice it. Why should the random addition of 100,000 neurons every day wreak any more cerebral havoc than their random subtraction? Brain regeneration may be quite possible, after all.

A third solution to the brain barrier problem is simply to prevent neural cells from dying at all, or at least to significantly slow the rate of attrition. We don’t know how to do this yet — perhaps more robust and wear-resistant cells could be designed — but alien sentients elsewhere may have already found the answer.

Assuming ETs and earthlings manage to lick the brain barrier problem, then exactly what are the limits to immortality? Saving the organ of sentience doesn’t get us out of the woods yet, because there is still the problem of accidental death associated with Stage 3. Individuals may be hit by a truck, slip in the bathtub, be shot in battle, or die in a plane crash.

Still, the lifespan in Stage 3 may be an order of magnitude greater than in Stage 1 (where humans are now). For example, the death rate in the United States in 1973 was 942 deaths per 100,000 people. The maximum lifespan attainable was about 100 years. If all purely medical deaths were eliminated, leaving only suicide, homicide and accidental causes (fire, drowning, lightning, and other sudden traumas), the death rate would have dropped to 78 cases per 100,000 people. This works out to a maximum attainable lifespan of nearly 1300 years, as shown in Figure 16.1.

Is this the upper limit, then? If accidental causes of death can be eliminated we can get more. But how could this be done? One recent science fiction story proposes the development of a sense of precognition or foreknowledge to enable the creature to anticipate accidents in the near future and avoid them.²⁶⁵⁰ This accomplished, there should be no further real limits to immortality, save boredom or a brain jammed to capacity with memories like a well-worn palimpsest. Death would occur only as a matter of affirmative, intelligent choice.

As we have seen, there are few limits to the possible accomplishments of alien biotechnologists. But the biological forms which nature has provided are especially well-adapted to a pretechnological planetary environment. ETs may need to design new forms to accomodate the requirements of a fast-paced industrialized technical society. Genetic manipulation might turn out to be a natural prerequisite to man-machine coupling. For example, gene surgery may permit body proportions to be altered to better fit the dimensions of mechanical systems such as computers and starships.

Sentient extraterrestrials thus may turn to synthetic biological or to bionically-augmented designs which possess the desired characteristics of high reliability, great longevity, and which interface more perfectly with various technological aspects of the environment. There are three general classes of such entities: Androids (purely biological), cyborgs (part biological and part mechanical), and robots (purely mechanical).

Table 16.2 Human Organ Transplant Biotechnology as of 19762365

Exactly what is an android? There seems to be much confusion on this score even among science fiction writers. Some hold that an android is an automaton in human form; others describe it as a robot that can think. Still others require it to be biological, while a few permit both biological and mechanical "androids." Perhaps the most consistent traditional definition is the one offered by Groff Conklin in 1954: "An android is a living being that has been created partly or wholly through processes other than natural birth."¹⁸³⁶

The classic biological android was the fictional Frankenstein monster created by the pen of Mary Shelley — a living organism assembled in pieces by men. Under the Conklin definition, clones would probably also be regarded as androids.

What of nonhumanoid forms? Arthur C. Clarke has coined the word "biot" (short for "biological robot") to refer to all animal androids, nonhuman beasts created by the hand of sentience. Remarks Freeman J. Dyson of the biot:

I would say that when we learn to use these biological techniques ourselves, and to build machines with biological materials, we shall probably be able to create intelligence. I think it will not look like an electronic computer, but rather more like a living organism.¹⁵⁵⁸

Jeremy Bernstein, Professor of Physics at the Stevens Institute of Technology in New Jersey, echoes this sentiment when he states:

The lesson of modern biology is that the distinction between living and nonliving material is almost arbitrary. So it is possible that one would be able to make machines biologically, in test tubes rather than in an electronics factory, and then it will be almost an arbitrary question as to whether one wants to call such objects machines or living animals.¹⁵⁵⁸

Terrestrial organ transplant technology has advanced markedly in the 1970s. As shown in Table 16.2, transplants of virtually every major human organ have been attempted with increasing success.* Furthermore, the art of microsurgery — essential fine detail work with tissues and capillaries involved in transplantation — has made fantastic progress. Skilled microsurgeons now suture tiny capillary walls and can reconnect delicate wisps of nerve tissue, working under a microscope with needle and thread smaller than human hair.²⁸⁸² For more than a decade, Chinese doctors have been replacing severed limbs with great success — arms, legs, feet and fingers. (Since the thumb accounts for 50% of the efficiency of the hand, microsurgeons can salvage it even when it's smashed beyond repair. One of the patients big toes is transplanted onto the thumb stump. "Close up it looks a little strange," remarked one writer, "but it does the job."²⁶⁵²)

Where might replacement organs come from? They could be cloned from the patient’s own cells, but this takes time. Another way would be to store donated or pre-cloned organs "on ice" until needed. Scientists at the Oak Ridge National Laboratory have developed a technique which may soon make it possible to store human organs for a century or more before thawing for use in a transplantation procedure.²⁶⁵³

William Gaylin, President of the Institute of Society, Ethics, and the Life Sciences, has proposed the controversial idea of using living cadavers, which he calls "neomorts," for medical experimentation and salvaging body parts. Neomorts — living, breathing, feeding and excreting organisms — would nevertheless be legally dead because of the cessation of electrical brain activity (brain death). Gaylin suggests that "bio-emporiums" be maintained using the victims of suicides, homicides and other accidents. Neomorts would serve as body part banks. Organs would be preserved in the still-living bodies, and there would be a regular supply of blood since the living corpses "could be drained regularly."²⁶⁵⁴

Science fiction writer Larry Niven predicts that widespread demand for donor organs might create a new type of crime which he calls "organlegging." As body parts change from a luxury for the few to a necessity for the many, demand will almost certainly outstrip supply. Niven claims that a black market in illegally-obtained organs would spring into existence, offering disassembled kidnap victims to the local Organ Bank at inflated prices.²⁰²⁰ As man becomes more android, will his crimes become more heinous?

What about brain transplants? About a decade ago, Dr. Robert J. White of the Brain Research Laboratory at Cleveland Metropolitan General Hospital carefully removed the brains of six dogs. Each organ was placed into the cranium of a new canine and connected to its bloodstream. Some animals perished within six hours of the operation, but one survived for two days. During this time, the living transplanted brain produced electrical signals on the electroencephalograph that was monitoring it.¹⁶⁴⁶ Similar experiments have been conducted successfully on monkeys.²⁶⁵⁶

But to transplant an entire brain and restore it to full capacity, extraterrestrial microsurgeons must be capable of severing and reconnecting countless millions of individual nerve endings in a very brief span of time. This will be a most challenging operation because the neural configurations in the donor brain, much like the uniqueness of fingerprints, will display a complicated pattern that probably won’t match the connections in the recipient’s cranium.

If the whole head is transplanted, however, the cranial nerves continue to function normally.²⁶⁵⁵ For this reason it has been suggested that aliens may prefer to transfer heads rather than brains. Human scientists have already tried this. In 1957 a Russian surgeon named Vladimer Demikov grafted a second head onto the neck of a dog. The two-headed monstrosity survived nearly a week with apparently "normal" functioning. For instance, when exposed to light and sound both heads responded by trying to bark.²³⁶⁵ Aliens may use similar methods to graft old heads onto freshly-cloned headless neomorts.

* A review of the medical literature available in 1976 fails to produce a single instance of penile transplantation.¹⁶²¹ However, 13 cases of replantation of the traumatically amputated penis are noted, and 10 cases of penile reconstruction are recorded in which a new penis was fashioned from other neighboring tissues. A major impasse to penile transplantation appears to be donor organ procurement.

What about the possibility of totally bionic brains? Might extraterrestrial biotechnologists be able to transfer personality and consciousness into virtually indestructible and immortal bionic bodies? In theory, there are no technical objections to "total prosthesis," as it is sometimes called. Using advanced atomic or molecular electronics, fully synthetic brains which function as well as or better than the originals can easily be imagined. However, one major difficulty is frequently overlooked.

In most schemes, the subject’s brain contents are somehow "read out" and recorded using sophisticated high-capacity computer data storage devices. This data is later played back and imprinted upon the tabula rasa bionic brain. The mortal flesh-and-blood organ is then replaced by the immortal synthetic one in the cyborg body. Upon awakening, it is discovered that the words, thoughts, and behavior of the new entity are indistinguishable from those of the original in every way.

But it is not the original! The cyborg is only a copy. A duplicate person has been created and the original (presumably) destroyed — its sentience, its self-awareness, its personal consciousness. The new bionic brain, perhaps graced with a blissful continuity of memory, may not be aware of the change at all. But the original self is dead nevertheless. (The author, for one, would hesitate to accept such immortality by proxy.)

This fundamental problem is difficult, but by no means impossible, to resolve. It may turn out to be relatively easy to transfer from a biological to a synthetic brain without any loss of self or interruption of consciousness in the original. Dr. Jonathan Boswell, a nuclear physicist at the University of Virginia, recently gave me one simple example of such a process:

I visualize the process of consciousness transfer as taking many years. First, biocybernetic electrodes would be implanted permanently in the brain of the aging patient. Many of them, so that the data pathways are wide. As the body decays — let us suppose it first goes blind — the consciousness inside finds that it can "see" through the cameras of the machine it's connected to. Later, it could hear, touch. … Placed in direct contact with the bionic brain, the two minds would begin to share the thinking function. Ultimately, when the old hulk of the body finally shrivels up and dies, the shared mind lives on without interruption in the synthetic brain.²⁶⁶⁵

Artificial intelligence expert Hans Moravec has come up with a somewhat more elaborate scheme:

You are in an operating theater, and a brain surgeon (probably a machine) is in attendance. On a table next to yours is a potentially human equivalent computer, dormant now for lack of a program to run. Your skull, but not your brain, is under the influence of a local anaesthetic. You are fully conscious. Your brain case is opened, and the surgeon peers inside. Its attention is directed at a small clump of about 100 neurons somewhere near the surface. It examines, nondestructively, the three dimensional structure and chemical makeup of that clump with neutron tomography, phased array radio encephalography, etc., and derives all the relevant parameters. It then writes a program which can simulate the behavior of the clump as a whole, and starts it running on a small portion of the computer next to you. It then carefully runs very fine wires from the computer to the edges of the neuron assembly, to provide the simulation with the same inputs the neurons are getting. You and it check out the accuracy of the simulation. After you are satisfied, it carefully inserts tiny relays between the edges of the clump and the rest of the brain, and runs another set of wires from the relays to the computer. Initially these simply transmit the clump’s signals through to the brain, but on command they can connect the simulation instead. A button which activates the relays when pressed is placed in your hand. You press it, release it and press it again. There should be no difference. As soon as you are satisfied, the simulation connection is established firmly, and the now unconnected clump of neurons is removed.

The process is repeated over and over for adjoining clumps, until the entire brain has been dealt with. Occasionally several clump simulations are combined into a single equivalent but more efficient pro gram. Though you have not lost consciousness, or even your train of thought, your mind has been removed from the brain and transferred to the machine. A final step is the disconnection of your old sensory and motor system, to be replaced by higher quality ones in your new home. This last part is no different than the installation of functioning artificial arms, legs, pacemakers, kidneys, ears and hearts and eyes being done or contemplated now.³²³³

Moravec then goes on to point out the many advantages that would become apparent as soon as the process was complete:

Somewhere in your machine is a control labeled "speed." It was initially set to "slow," to enable the simulations to remain synchronized with the rest of your old brain, but now the setting is changed to "fast." You can communicate, react and think at a thousand times your former rate.

Major possibilities stem from the fact that the machine has a port which enables the changing program that is you to be read out, nondestructively, and also permits new portions of the program to be read in. This allows you to conveniently examine, modify, improve and extend yourself in ways currently completely out of the question. Or, your entire program can be copied into a similar machine, resulting in two thinking, feeling versions of you. Or a thousand, if you want. And your mind can be moved to computers better suited for given environments, or simply technologically improved, far more conveniently than the difficult first transfer. The program can also be copied to a dormant information storage medium, such as magnetic tape. In case the machine you inhabit is fatally clobbered, a copy of this kind can be read into an unprogrammed computer, resulting in another you, minus the memories accumulated since the copy was made. By making frequent copies, the concept of personal death could be made virtually meaningless. Another plus is that since the essence of you is an information packet, it can be sent over information channels. Your program can be read out, radioed to the moon, say, and infused there into a waiting computer. This is travel at the speed of light. The copy that is left behind could be shut down until the trip is over, at which time the program representing you with lunar experiences is radioed back, and transferred into the old body. But what if the original were not shut down during the trip? There would then be two separate versions of you, with different memories for the trip interval.

When the organization of the programs making up humans is adequately understood, it should become possible to merge two sets of memories. To avoid confusion, they would be carefully labeled as to which had happened where, just as our current memories are usually labeled with the time of the events they record. This technique opens another vast realm of possibilities. Merging should be possible not only between two versions of the same individual but also between different persons. And there is no particular reason why mergings cannot be selective, involving some of the other person’s memories, and not others. This is a very superior form of communication, in which memories, skills, attitudes and personalities can be rapidly and effectively shared.³²³³

Table 16.3 Molecular Fineness and the Thermodynamic Significance of Patterns of Information (modified from Morrison1704)

Can machines live? Evolve? Think? Many scientists would answer in the negative. Gears, relays, and integrated circuits certainly aren’t alive in the traditional sense. Evolution typically involves reproduction and natural selection, but no Earthly machines are known to reproduce themselves. And, it is said, cold steel cannot cogitate.

From the xenological point of view, however, we’ve already determined that the most useful definition of life involves the concept of negative entropy, or negentropy.

That is, to be considered "alive" an entity must:

• Feed on negentropy (absorb order from the environment)
• Store negentropy (create order within itself)

Figure 16.3 Microstructure in Machine Lifeforms and Biological Lifeform Inhabiting the Planet Earth

The amount of stored information in a living organism determines exactly how alive it is.

Philip Morrison at MIT has taken a first stab at a quantitative analysis of "how much life" is present in any entity of specified complexity.

It will be recalled from {tip content="Reference: 6.2.3 Towards a Definition of Life
Paragraph #29, Begins: The refrigerator in my house"}Chapter 6{/tip} that a refrigerator or other similar contemporary machine technically is "alive" by our definition, because it feeds on negentropy and uses this to create internal order.

But most machines "alive" today aren’t very alive because they store only miniscule amounts of information at the molecular level.

Morrison has shown that patterns imposed on lumps of inert matter will not begin strongly to affect the matter thermodynamically "until the pattern is constructed with molecular fineness."¹⁷⁰⁴

His calculations, summarized in Table 16.3, pertain to an hypothetical black-and-white
checkerboard pattern superimposed on a slab of otherwise inert matter.

We may view the last column of Table 16.3 as representing, in a sense, the intensity of life achieved by an information-laden pattern imposed on inanimate matter, Clearly, the finer the pattern (Figure 16.3), the more "alive" is the entity.

By implication, we cannot concede that machines are "very alive" until their components are constructed with molecular fineness. Only then will the information storage in machines be comparable to those found in biological lifeforms.

The need for a biochemistry as a prerequisite of organic life is far less compelling for beings of purely artificial construction. As such creatures perhaps can be modified or repaired simply by replacing modular parts, the only fundamental requirement appears to be Morrison’s "molecular fineness of construction." The distinction between biological and mechanical life be comes quite blurred — are not machines constructed of iron and silicon with molecular patterns examples of "ferrosilicon-based lifeforms"?

Robots are now on the human scene in all but their most advanced forms. One writer has observed that "robots are at about the same stage as electronic calculators about a decade ago… . Specialists in the field suggest that ten years from now robots will be as common as calculators are today."²⁶⁸¹

The word "robot" itself comes from a 1920 play written by the late Czech author Karel Capek entitled Rossum’s Universal Robots. In this early science fiction tale of the future, sentient robots revolt against human-enforced slavery and conquer the world themselves.

One of the first writers with the courage to portray intelligent mechanical beings as benign, or at least indifferent, was Dr. Isaac Asimov. His well-known Three Laws of Robotics — intended to be incorporated into the basic psychology of every sentient machine — were designed to prevent a revolt against biological creators such as was envisioned by Capek:

While these rules may guide human planners, there is no guarantee that extraterrestrial robots will obey the Three Laws or any similar failsafe system. ETs may choose to give their automatons considerably greater freedom of action, especially if they are the products of "total prosthesis" (biological consciousness transferral). Mechanicals from other worlds designed to perform military, emergency rescue, or political functions may require considerably more autonomy than Asimov’s Laws would permit.

Figure 16.4 Humanoid Robot-Building Technology: Terrestrial State-of-the-Art Figure 16.4 Century I Klatu Leachim Figure 16.4 Humanoid Robot-Building Technology Figure 16.4 Humanoid Robot-Building Technology: Terrestrial State-of-the-Art Century I Century I is a 2-meter, 300-kilogram (7-foot, 650-pound) bullet-proof automated security guard. The $75,000 robot was unveiled at the 1977 annual seminar of the American Society for Industrial Security. The humanoid’s sensors detect movement, body heat, or noise and lock onto the source. At speeds up to 30 kph (20 mph), Century I closes on its quarry. When it gets within about 3 meters, it orally instructs the intruder to halt with an imperious voice. If disobeyed, the robot gets tough. Standard equipment includes an ultrasonic sound transmitter that causes extreme pain in the inner ear. A blinding strobe light, an electronic pistol that shoots powerful shocks, and a spray gun filled with laughing gas are also available. While admitting that Century I could be programmed to kill, Anthony J. Reichelt of Quasar Industries Inc. (Rutherford, N.J.) added that his firm plans to use only "nonlethal restraint" in its machines. Quasar is also developing a $125,000 Century II robot for the U.S. Army. "Once he’s put on program," explained inventor Reichelt in regard to the improved model, "nobody can stop him."2702 Klatu Another product of Quasar Industries, Klatu is seen as a possible prototype for the first "domestic android." At 1¼ meters tall and 80 kilograms (5 feet, 180 pounds), the robot reputedly may be programmed to accept a wide variety of household chores. According to Reichelt, president of Quasar, Klatu can: Vacuum floors, greet guests and take their coats, serve drinks and dinner, guard the house, walk the dog, clear dishes from the table, wash windows, speak "intelligently" with a 250-word vocabulary, and play nursemaid to the children and the bedridden. Robotologists and other experts in the scientific community are skeptical. The price — a cool $4000.2703 Leachim Grade school students at Public School 106 in the Bronx receive instruction from a robot substitute teacher. The picturesque 1¼-meter, 90-kilogram (5'5", 200-pound) automaton with black plastic arms and legs was created by Dr. Michael Freeman for only $1000. (The legs are motorized, but the robot is chained to a table for security.) The humanoid’s brain is a computer, made partly from components cannibalized from an RCA Spectra 70. Leachim has memorized parts of Compton’s Encyclopaedia, Webster’s New World Dictionary, a Ginn science book, a thesaurus and a Macmillan reading series, as well as the national anthem, the Pledge of Allegiance, Aesop’s fables, a round of jokes, a few words in Spanish, and detailed biographical and educational information for each student.2693

Terrestrial robotics technology is actually fairly advanced in the area of physical locomotion (Figure 16.4). Human roboticists at Stanford Research Institute (SRI) have constructed an computer-directed automaton with wheels, two retractible arms, and a television camera mounted in its "head." The device, nicknamed "Shakey," is free to roam about a room strewn with objects of various shapes and sizes. The SRI robot can be programmed to perform specific lifting, moving and stacking operations. (E.g., "Pick up the smallest cube and take it to the doorway."¹⁷⁷⁹

The Russian automated lunar rover Lunakhod is a mobile eight-wheeled robot with TV camera eyes, able to navigate the surface of the Moon. Soviet scientists also are developing a spider-like surface exploratory vehicle that will be able to cross obstacles impassable by wheeled or caterpillar-tracked machines. This device, now under development at the Leningrad Institute of Aviation Instrument Makers, has six legs, a computer "brain," and a laser eye that scans ahead for trouble.¹¹³⁸ It reportedly can negotiate steep slopes, stairs, narrow corridors with sharp turns, and landscapes littered with stones or fallen trees.²⁶⁹⁴

Mechanical "feeding" has also been accomplished. Robots have been designed that are capable of searching for "food" and thus of maintaining their own active existence. Dr. W. Grey Walter designed a small electronic turtle in his laboratory in Bristol, England, decades ago. Dubbed Machina speculatrix by its creator, Walter’s "machine lifeforms" each consisted of two tiny radio tubes, a photoelectric cell and a touch sensor, motors for crawling and steering, and a light bulb for "speaking," all hooked up to a miniature 6-volt storage battery.¹⁷⁸³

Each robot exhibited various interesting behaviors. When the battery ran low, the turtle was programmed to hunt for its "hutch" where it could plug in and recharge.* When placed in front of a mirror, the device displays a primitive form of self-recognition. An encounter between two mechanical creatures is described by Walter thus: "Each, attracted by the light the other carries, extinguishes its own source of attraction, so the two systems become involved in a mutual oscillation, leading finally to a stately retreat."²¹⁰⁶ Later models were equipped with microphones so they could respond to whistles. More complicated circuitry allowed more variable behavior as well as the ability to "learn."⁶⁰ With a behavior repertoire attributable to no more than 1000 bits, the intelligence of Machina speculatrix probably rivals that of the rotifer.

The purpose behind Walter’s work was to demonstrate that quite simple machines could fairly well mimic the goal-seeking ability of animals. All the major attributes of life on Earth — feeding, metabolizing, mobility, response to stimuli and so forth — can and have been designed into various machines built by humans.¹⁷⁸² We’ve seen that emotions and intellect can be impressed upon artificial structures. There appear to be no real limits to the complexity of organization and behavior that might be displayed by alien robots. Indeed, extraterrestrial automata may even have the ability to reproduce.^{85, 956}

Von Neumann demonstrated during the 1940’s that self-reproducing machines are quite possible in principle.¹⁷²⁶ Basically, the problem is to find the proper parts and to know how to put them together. Von Neumann envisioned a machine that could move around in a special stockroom, selecting the pieces required to build another machine exactly like itself — and then doing so. Such a device necessarily consists of two parts: One part to build a duplicate copy, and another part able to program the duplicate so it can make more copies too. (This is analogous to the distinction between phenotype and genotype in biology.²³⁶⁴) According to one computer scientist, such a reproducing system could be as small as 150,000 bits of information.¹⁷³⁷ [Note added: A general review of kinematic self-replicating machines was published by the author in 2004 and is available online at http://www.MolecularAssembler.com/KSRM.htm.]

A large population of such organisms would constitute an ecology. They will evolve. Wrote von Neumann:

If there is a change in the description … the system will produce, not itself, but a modification of itself. Whether the next generation can produce anything or not depends on where the change is. So, while this system is exceedingly primitive, it has the trait of an inheritable mutation, even to the point that a mutation made at random is most probably lethal, but may be nonlethal and inheritable.¹⁷²⁶

Sentient alien automata thus may be "alive" both in the popular as well as the technical sense.

* Anyone interested in building such a device should consult Huber’s article "Free Roving Machine," which contains specifications and circuit diagrams for a similar system.¹⁷⁸⁴ A more ambitious design for a "mechanical pet" may be found in Heiserman’s Build Your Own Working Robot.²⁶⁸³

Alien and human astronauts alike must conform to the dictates of Relativity when traveling at velocities near the speed of light. Einstein’s theory, generally accepted today by the scientific community, predicts a host of fascinating consequences of near-lightspeed voyages.

First, we should briefly mention some of the jargon commonly employed by physicists and writers in this field. Relativity predicts that no material object can be accelerated up to the speed of light without an expenditure of an infinite amount of energy. Since the entire universe contains only 10⁸¹ joules of energy, attaining the speed of light becomes a practical impossibility. The velocity of light, designated as "c", this is a kind of "cosmic speed limit" imposed on all material objects within the physical universe. (Other jargon for c includes "100 psol" or percent-speed-of-light, and "Mike 1.0" after Dr. Albert A. Michelson.) Velocities below c are referred to as "suboptic" or "subluminal"; those faster than light are called "FTL," "hyperoptic" or "superluminal." The speed of light itself is "optic velocity."

Now back to the fascinating consequences. According to Relativity theory, time passes more slowly at near-optic velocities than at low suboptic ones. This apparent breach of common sense is traditionally presented in the form of a paradox. Imagine twin brothers A and B. A becomes an astronaut and flies away in a relativistic starcraft capable of a peak velocity of 98%c. B stays behind on Earth. A travels 12 light-years out into space, and then 12 light-years back to Earth. Because A has been moving slower than light, B must wait a total of 28 years for his return. B is thus 28 years older than his age when the brothers parted. But when he meets A in the Debarkation Area, A has only aged 10 years. A is 18 years younger than his identical twin.

This unusual consequence of near-optic flight, often called the Twin Paradox, has been confirmed indirectly by scores of experiments over the past half-century. There is little doubt in the minds of most physicists that the Paradox is a correct prediction of the consequences of traveling close to the speed of light. The contraction of time at high velocities is known as the phenomenon of time dilation.

Table 17.1 Effective FTL Starflight Using Relativity Theory

The frame of reference of the observer is of critical significance here. Those observers who remain at rest with respect to the universe at large (such as the twin who stays on Earth) will always observe a relativistic starcraft to travel at suboptic velocities. But to the astronauts on board the spaceship, the contraction of distance between the points of origin and destination (another peculiar consequence of Relativity theory) will make the trip seem shorter. They will, from their frame of reference, actually be moving at a faster apparent velocity than that perceived by stationary observers (say, back on Earth). In fact, when the starship reaches exactly 70.7%c as measured by stationary observers, the astronauts calculate their own effective velocity as 100%c! As acceleration continues still further, shipboard-determined speed increases to seemingly hyperoptic velocities (which Earthbound observers still see as suboptic from their frame of reference).

Table 17.2 Duration of Interstellar Travels, Using a Standard Flight Plan at One Gee Acceleration

What does all this mean in plain English? Simply this: An astronaut, provided his starcraft has sufficient energy, can effectively travel faster than the speed of light relative to a stationary frame of reference! (See Table 17.1 for details.)

Time dilation permits very long journeys within a single human lifetime. Consider a starship that accelerates uniformly to the midpoint of the trip and then decelerates uniformly at the same rate the rest of the way to the destination — called the Standard Flight Plan.

With an acceleration of 1 gee — appropriate for inhabitants of terrestrial worlds similar to Earth — only a few years of ship-time are required to reach the nearest stars. (See Table 17.2.) Only 21 years are spent reaching the Galactic Core, and in 28 years of shipboard time the intrepid explorers can visit Galaxy Andromeda in person. Since Andromeda is about 1.7 million light-years distant, this works out to a mean effective velocity of 61,000 times the speed of light.

Of course, there is no time dilation on the home planet — since it went nowhere. If our intergalactic astronauts turned around at Andromeda and immediately returned to Earth, they would have aged a total of 56 years. The Earth and all of its inhabitants, however, would have aged 3.4 million years. This is a "twin paradox" with a vengeance!

Table 17.3 Acceleration Required to Complete Journey in One Decade Shipboard Time, Using Standard Flight Plan

When science fiction writers and others speak of "FTL" they are usually referring to true (rather than "effective") FTL — that is, faster-than-light travel from the point of view of both astronauts and stay-at-homers. We shall discuss the theoretical possibility of true FTL later in this chapter. But for now it is important only to realize that Relativity does permit effectively hyperoptic interstellar journeying, at least from the standpoint of an astronaut setting forth to explore the universe.

This fact is highlighted by the data shown in Table 17.3. It is assumed that an astronaut wishes to travel a certain distance out into space, but he doesn’t want to use up more than 10 years of his life in getting there. Table 17.3 lists the starship accelerations that must be sustained throughout the entire trip in order to arrive at a destination at the specified distance within exactly one decade as measured on the astronaut’s own wristwatch. A Standard Flight Plan is assumed.

Note that any point in our Milky Way galaxy can be reached in ten years of shipboard time, at accelerations tolerable to human beings for long periods of time. Accelerations of 2-4 gees, perhaps sustainable by inhabitants of jovian or heavy subjovian worlds, or by bioneered former inhabitants of terrestrial worlds, would put the entire known universe within 10 years reach.

Naturally, the faster a starship is pushed the more energy is required. The levels of power expenditure needed to achieve the benefits of relativistic time dilation are enormous by today’s standards, even for fairly small vehicles. (See Table 17.1.) But as we shall see presently, this by no means bars interstellar or intergalactic commerce. Indeed, such commerce should be commonplace among Type II and Type III civilizations.

Let us consider three illustrative classes of starflight missions:

• 1. Interstellar personnel transport;
• 2. Intergalactic personnel transport;
• 3. Intergalactic cargo transport.

Too many writers have succumbed to the Fallacy of the Big and the Costly. That is, if it’s big and it costs a lot, it must be impossible. The Fallacy lies in the simple observation that what seems big and costly to one culture may be negligible and cheap to another.

The relative costs of missions to the stars may perhaps best be appreciated by a comparison with the familiar. Humanity has launched about ten Saturn V rocket boosters to date. Each of these blustering behemoths developed 1.3 × 10¹¹ watts of power for about 150 seconds each. This is the equivalent of harnessing the entire human energy output for exactly 4 seconds. Keep this quantity in mind as we work through the following examples: One Saturn V equals 4 seconds of humanity’s aggregate power output.

First we consider the interstellar personnel transport mission. We assume a flight distance of 100 light-years, appropriate for short hops between neighboring Type II civilizations. To make things comfortable for the pilots and passengers, we further assume a Standard Flight Plan at a constant 1 gee acceleration. Using the equations of Special Relativity, total trip time works out to a mere 9 years.

How much energy is required? If we take the mass of the vessel to equal that of the Starship Enterprise of original-series Star Trek fame (190,000 metric tons), then about 9 × 10²⁶ joules of energy are required for the mission. A mature Type II civilization, having 10²⁶ watts (joules/sec) at its disposal, should have no trouble with this at all. The interstellar personnel transport mission uses only nine seconds of the culture’s total power output, a feat equivalent in stature to the launching of two Saturn V rockets by modern human engineers. For a Type III civilization, this mission is inordinately trivial. In fact, roughly 44 billion such starliner missions could be dispatched if only 4 seconds of the galactic society’s aggregate energy output were utilized — a feat comparable to the launching of a single Saturn V from Earth today.

What about our second class of starflight mission — the intergalactic personnel transport? These are somewhat more difficult, probably well out of reach of a lone Type II civilization. Again, using a Standard Flight Plan at 1 gee acceleration to keep crew and passengers at ease, a trip of 1.7 million light-years to Galaxy Andromeda (the nearest giant spiral) would require only 28 years shipboard time. Approximately 1.5 × 10³¹ joules would be consumed making the journey.

Such a mission would tax the resources of Type II culture to the breaking point. More than 41 hours of the stellar society’s power output would be needed to launch a single intergalactic starliner, a feat analogous to the firing of 38,000 Saturn V’s by present-day humankind. Such an enormous sacrifice and commitment of resources would require some overwhelmingly compelling purpose to justify it.

For a mature Type III galactic civilization with 10³⁷ watts under its control, however, the intergalactic personnel transport mission would again prove utterly trivial. Such a culture could launch more than 2.5 million such sorties to Galaxy Andromeda for a mere 4 seconds worth of its total power output — again, a feat comparable to our launching a single Saturn V rocket.

Finally, we consider the case of the intergalactic cargo transport mission. Since these ships can be unmanned, far higher accelerations may be tolerable. We assume a robot-controlled, 190,000-metric-ton cargo ship, dispatched to Andromeda at an acceleration of 10⁶ gees (probably the upper limit for normal physical materials) on a Standard Flight Plan. Fortunately, the shipboard time of flight is only 1724 seconds, a bit under half an hour, so the ship and its contents are subject to extreme forces only for a very brief period of time. A total of 1.5 × 10³⁷ joules are required for the mission, about 1½ seconds of the aggregate power output of a galactic culture. To a Type III civilization, the launching of two such high-acceleration cargo vessels requires a resource commitment equivalent to the launching of one Saturn V by human technologists.

So we see that galactic and intergalactic commerce and tourism are very real possibilities for advanced extraterrestrial societies. The dispatch of an interstellar personnel carrier by a Type II culture, or a high-acceleration intergalactic cargo transport vehicle by a Type III culture, represents about the same allocation of energy and resources as the launching of a Saturn V rocket by human Type I civilization.

Three fundamental requirements must be satisfied if starflight is to be considered plausible for alien or human civilizations. First, the kinematics must be right. Second, the energy available for the mission must be sufficient. Third, there must exist an astronautic technology capable of performing the requisite kinematics using the available energy. In the preceding section we saw that the kinematic and energetic requirements are satisfied by Type II and Type III civilizations operating within the bounds of Einsteinian Relativity theory. For the remainder of this chapter the third requirement is examined in more detail — the technological aspects of interstellar voyaging.

Consider the nature of technical progress. There is an orderly progression from the emergence of new ideas, further research and development, then finally a reduction to practice and economic exploitation. Thus, the realization of new technology normally proceeds in four stages:

• Stage 1 — IDEA — the basic philosophical idea, discovery of a new physical law, a new branch of mathematics, a new possibility within the existing framework of science.
  (See Hogan²⁹¹⁶ for an excellent example of this in science fiction.)
• Stage 2 — THEORY — development of the mathematical/physical theoretical framework which ties the new idea to other known phenomena.
• Stage 3 — PRACTICE — research and engineering; building a device which utilizes the new idea in its manufacture or operation.
• Stage 4 — PROFIT — social, political, and economic acceptance and exploitation; who pays for it, is it worth the effort, who will benefit, etc.?

Matching this progression against current human achievements, we find that radio, television, computers, automobiles, and chemical rockets all have arrived at the profit stage here on Earth. Such advanced technologies as nuclear power planets, SSTs, and fission propulsion rockets are at the practice stage, awaiting full societal and economic commitment to move them into the profit stage. Laser fusion and satellite solar power stations are presently in transition from theory to practice.

The five conventional interstellar propulsion systems described in this section are all at the theory stage in human technological development. Each has received sufficient study to tell us that they have the basic physical and energetic feasibility to be considered for missions to the stars. All retain a number of technical uncertainties which will require significant engineering effort to overcome. Nevertheless, xenologists expect that all five propulsion systems are likely to advance at least to the practice stage within a century or less on this planet. So it is likely that these same systems also accurately represent the interstellar transport technologies of many extraterrestrial sentient races in the universe.

A sixth conventional interstellar propulsion system employing paired high-energy mass drivers for efficiently transporting massive cargoes between distant stars is briefly described in Section 21.4.1.

Figure 17.1 Project Orion (from Dyson478) Figure 17.2 Nuclear Pulse Vehicle (from Forward718,2812)

In the 19th century Hermann Ganswindt proposed the use of a series of gun powder charges behind a vessel to propel it into space.²⁷⁶² The concept of nuclear pulse propulsion, the modern extension of this basic idea, was developed under USAF contract at Gulf General Atomic during the years 1958-1965.

Dubbed "Project Orion" by the scientists who worked on it, the system operates by tossing out a nuclear bomb, exploding it astern of the ship, and absorbing part of the momentum of the resulting debris. The rocket thus consists of at least five distinct parts: An hemispheric ablation shield or "pusher plate," an enormous shock absorber, a mechanism for ejecting the bombs, the bomb magazine, and finally the payload at the front end. Small test models using steel pusher plates and TNT charges were successfully flown during the experimental phase of Project Orion, but the work was shelved after the Nuclear Test Ban Treaty entered into force late in 1963. (The Treaty prohibits the explosion of nuclear devices in the atmosphere or in space.)

Freeman J. Dyson of the Institute for Advanced Study at Princeton, New Jersey, who worked on Project Orion, described a prototype model of a space vehicle utilizing the principle of nuclear pulse propulsion.⁴⁷⁶ His "Ablation Space Ship" has a total mass of 400,000 metric tons, consisting of 300,000 tons of one-megaton H-bombs (weighing 1000 kg each), 50,000 tons of structure and payload, and 50,000 tons of ablation shield. The pusher plate construction is such that about 30 meters/second forward velocity are imparted to the vessel with each explosion. A smooth 1-gee acceleration is maintained by the detonation of one bomb every three seconds, which requires a shock absorber stroke length of about 75 meters (Figure 17.1).

Dyson’s nuclear pulse vehicle exhausts its bomb supply in ten days, having reached a final velocity of 10,000 km/sec (about 3.3%c). The flight time from Earth to Proxima Centauri would then be 130 years for a simple flyby mission. For an encounter-capture mission the payload must be decelerated at the target, which more than doubles the time of flight for a vehicle of this size.

More efficient variants of the nuclear pulse technique have been suggested in recent times (Figure 17.2), particularly the idea of igniting tiny deuterium pellets instead of huge bombs behind the ship. Ignition would be achieved using pulsed laser beam fusion^2751,2752 or heavy ion or electron beam fusion.²⁷⁶⁴ This latter technique has been selected for use in the Daedalus starprobe, an interstellar vehicle designed as part of a feasibility study sponsored by the British Interplanetary Society during 1975-1977.²⁹⁵³ In the Daedalus system, a 54,000-ton craft is propelled up to 12%c using a stream of frozen deuterium/helium-3 pellets which are zapped by a megavolt electron gun 250 times a second. The designers claim that the probe should be able to reach Proxima Centauri in 35 years with a 500-ton payload.²⁷⁶¹

Montage of fusion-powered interplanetary spacecraft concepts from 1987-2004 (from Wikipedia)

Another highly promising starship propulsion system is the technique of using a controlled, continuous thermonuclear fusion reaction as the main power source. Because of the tremendous temperatures involved (upwards of 10,000,000 K), no known material can physically contain a fusion reaction. Magnetic fields therefore must be used to contain, compress, and heat the plasma fusion fuel (hydrogen, deuterium, tritium, etc.). Scientists are currently engaged in designing and testing various "magnetic bottle" configurations strong enough to hold such an energetic plasma, in connection with electrical power generation at major fusion research facilities around the world.

The biggest problem is to make the magnetic bottle leakproof enough so that fusion reactions occur in sufficient abundance for the process to become self-sustaining. In terms of propulsion, however, a leaky bottle is exactly what is required. Hot plasma, energized by fusion energy, streams rapidly from the site of the "leak" and produces the desired rocket thrust.

According to Dr. Robert L. Forward, Senior Scientist at Hughes Research Laboratories, a deuterium fusion rocket capable of a steady 1-gee acceleration and consisting 90% of fuel (by mass) could reach a final velocity of 10%c.⁷¹⁸ This would mean a travel time to Proxima Centauri of 45 years. Theoretically, a fusion-powered starship could be fueled by hydrogen isotopes drained from the atmosphere of Jupiter or from the icy rings of Saturn, and writer Alan Bond has estimated that a 10 light-year mission could be completed in 60 years.¹¹⁵⁹

One major problem to be overcome from a practical standpoint is to learn how to deal with the various forms of energy released by a fusion engine. Only about 20% of the energy liberated by nuclear reactions appears as kinetic energy — direct propulsive thrust — in the leaking plasma stream. Ten percent is thrown off as heat and ultraviolet radiation, but the lion’s share (70%) is released as X-rays. G.L. Matloff and H.H. Chiu have suggested that this energy may be reclaimed by using an auxiliary laser thruster surrounding the fusion reaction chamber.²⁷⁵⁴ Waste X-rays, absorbed by, say, xenon-doped gas in the laser, are converted into a collimated light beam which serves as a photon thruster.*

* A wide variety of related but "futuristic" propulsive energy systems may be possible. These may include:

• Condensed cold neutron reactions
• Pion fusion (which has been demonstrated experimentally)
• Muon catalysis fusion,²⁷³⁷
• Hawking black hole induced fusion¹⁹⁴⁷
• Compact monopole fusor and energy storage devices or magnetic monopole metamatter.¹²²⁴
• Fission rockets are not ruled out²⁷⁵⁸
• High-energy superpropellants such as monatomic hydrogen, metallic hydrogen,²⁶⁸⁴ cryogenic metastable triplet helium (stores 0.5 megajoule/gram) may be available.²⁷³⁶

Figure 17.3 Bussard Interstellar Ramjet2812

The interstellar ramjet, first proposed by Dr. Robert W. Bussard at Los Alamos Scientific Laboratory in 1960, is a propulsion system which acquires energy and reaction mass from the surrounding medium.²⁷⁶⁶ Using some combination of electric and magnetic fields, the ramjet scoops up ionized interstellar gases to fuel its fusion rockets. This eliminates the need to carry large masses of fuel on board. Conventional chemical or nuclear rockets must be used to accelerate the starrammer up to about l-5%c, the threshold velocity at which the ramscoop mechanism becomes reasonably efficient.

The forward scoop would be immense (Figure 17.3). Bussard originally calculated that a 1000-ton vehicle would require a funnel diameter of 3600 kilometers to achieve a one-gee acceleration in normal interstellar space (~1 H-atom/cm³). In regions of dense hydrogen clouds, with perhaps 103 atoms/cm³, the ramscoop diameter could be as small as 120 kilometers. Theoretically, the acceleration could be maintained indefinitely, making possible the circumnavigation of the entire universe in less than a human lifetime.²⁷⁵⁵

Such monstrous scoops, of course, need not be constructed of physical materials. Most probably electromagnetic fields will suffice. To generate such fields, A.J. Fennelly of Yeshiva University and G.L. Matloff of the Polytechnic Institute of New York proposed in 1974 an annular copper cylinder coated with a layer of superconducting tin-niobium alloy (Nb₃Sn).¹⁴⁵⁴ The device would be rather modest in size (as starships go), measuring 400 meters in length and 800 meters in diameter. Energized with electrical current, an electromagnetic scoop with an effective diameter of 10⁴ kilometers would be generated. For braking at the destination, a drogue chute made of boron (noted for its high melting point) about 10 km in diameter is recommended. (An electrically charged wire mesh would give sufficient drag without being destroyed by erosion.^1066,1061)

As if to underscore the tremendous engineering difficulties involved in scoop design, Fennelly and Matloff announced in 1976 their original device was simplistic and probably would not work:

It is not possible, we have found, to design such a scoop. The {forces} induced … stress a scoop beyond the elastic limit of the substrate material and shear the superconductor to such an extent that it will be driven to a normally resistive state, with a subsequent catastrophe from the almost instantaneous Joule heating.¹⁶¹⁵

Nevertheless, assert the authors gamely, "we have hope that further analysis will lead to feasible scoop designs with some type of electromagnetic field to give a large scoop effective radius." It is now believed that a mixed electrostatic/electromagnetic field design will give the best results. (See Matloff,²⁷⁵⁹ Matloff and Fennelly,²⁷⁶⁶ and Powell.²⁷⁶⁰)

By adding "wings" to the starrammer, travel times may be cut in half.²⁷⁸² Explains one writer:

The wings are two great superconducting batteries, each a kilometer square. Cutting the lines of the galactic magnetic field, they generate voltages which can be tapped for exhaust acceleration, for magnetic bottle containers for the power reaction, and for inboard electricity. With thrust shut off, they act as auxiliary brakes, much shortening the deceleration period. When power is drawn at different rates on either side, they provide maneuverability — majestically slow, but sufficient — almost as if they were huge oars.²¹⁸⁰

The Bussard ramjet is perhaps the most intensively scrutinized potential interstellar propulsion system. As a result, scientists are beginning to call attention to collateral problems involved in the design and operation of ramscoop vehicles.¹¹⁵⁵ One objection voiced by John Fishback in 1969 is fundamental.¹⁴⁶¹ He points out that the section of the starship which contains the sources of the magnetic scoop fields must be strong enough to withstand the forces generated by those fields. As the starcraft goes faster and faster, the required field strengths also increase. Since materials are limited by their maximum tensile strength, at some point the acceleration of the vehicle will have to be reduced to avoid the breakdown of its structure caused by the pressure of magnetic forces.¹⁴⁶²

For realistic building materials, this cut-off velocity at which further acceleration must be drastically curtailed occurs at about 99.999998%c. This is high enough to be of no practical significance for galactic travel at 1 gee, but may prove restrictive for higher acceleration rammers or for starships on intergalactic missions.

Another major difficulty, noted by Bussard and many others since, is that the proton-proton nuclear reaction is a poor candidate for fusion rockets. Most of the gas likely to be scooped up by the interstellar ramjet will be ordinary hydrogen, and hydrogen is very finicky when it comes to fusion. Deuterium reactions have a cross-section roughly twenty orders of magnitude greater, but this heavy isotope of hydrogen is relatively rare in the interstellar medium.

Recently, Daniel P. Whitmire has suggested the concept of a catalytic nuclear ramjet to overcome this problem.¹⁴⁷¹ In Whitmire’s scheme, the starship would carry on board a supply of "nuclear catalyst" consisting of carbon, nitrogen, and oxygen atoms. This fuel additive should catalyze a vastly increased reaction rate among ordinary hydrogen atoms without itself being consumed. Calculations indicate that this technique will yield a rate of fusion more reasonable from the standpoint of interstellar missions. For this scheme to succeed, of course, a workable heavy ion fusion reactor must be developed, but, in Whitmire’s words, "the difficulty seems to be of a technological rather than fundamental nature." (He also proposes the use of a bank of forward lasers to ionize neutral atoms approaching the rammer’s maw, thus greatly increasing the reaction mass available for the starship’s engines.)

An interesting hybrid variation of the basic ramscoop technique involves a vessel that carries its own nuclear fuel supply and exhausts the reaction products for thrust, much like a conventional fusion rocket. However, this Ram Augmented Interstellar Ramjet, or RAIR as Alan Bond of the British Aircraft Corporation calls his device, enhances its performance by scooping up atoms from the interstellar medium and using them as reaction mass rather than for energy generation.¹⁴⁵⁵

In other words, fusion fuel is carried by the spaceship and additional reaction mass is collected from gas clouds through which the vessel passes. Preliminary calculations show that the RAIR design may save at least an order of magnitude of fuel savings at speeds up to 50%c, and as much as two orders of magnitude of fuel savings up to 70%c. Performance characteristics of RAIR starships have been worked out by Bond¹⁴⁵⁵ and Powell.^{1117,1115,2769}

Two other fascinating variations on the interstellar ramjet have been proposed by Whitmire and A.A. Jackson IV.²⁷³³ The first of these is called the Fusion Ramjet Runway. Micron-sized frozen deuterium pellets are accelerated electrostatically or electromagnetically out into space several years prior to the launching of a standard Bussard ramjet having a comparatively small scoop cross-section (perhaps it would be just a simple physical structure, such as a giant funnel). The starrammer could then collect a more concentrated fuel en route simply by staying on the "runway."

The other suggestion, rather bizarre and considerably less likely, is the Stellar Ramjet. This vehicle accelerates up to near-optic velocity across the photosphere of a star. Whitmire and Jackson propose that the envelope of a red giant or a large protostar would be ideal for this technique. Accelerative forces would be large but not prohibitive, and biological crews should survive if they are somehow immobilized or "frozen" during the starship’s relatively brief period of acceleration.

Figure 17.4a Beamed Power Propulsion Laser-Pushed Vehicle718 Figure 17.4b Beamed Power Propulsion Laser-Pushed Vehicle718

We have seen that it may be best to use an external source of energy to achieve near-optic speeds. The interstellar ramjet discussed above is a good example of this technique. Another possibility is the Laser Pushed Vehicle, or LPV.^122,2767

The LPV obtains its energy and momentum from a solar-system-based laser network which pushes the ship by photon reflection from an onboard mirror. Calculations indicate that a power of roughly 10¹⁴ watts delivered to a 100-ton starship should be sufficient to impart a one-gee acceleration to the craft. Focusing would be of critical importance, and it may turn out that only x-rays will have a small enough wavelength/diameter ratio to forestall gross energy wastage. Upon arrival at a destination, LPV deceleration is effected in reverse fashion with the active assistance of the receiving civilization.²²

What if there is no receiving civilization? Is the Laser Pushed Vehicle strictly limited to one-way flyby missions of exploration? The answer, apparently, is no.

According to Philip Norem, a space-based laser system could be used to accelerate a starprobe up to relativistic velocities. After a while, the craft extends long wires and charges them up to high voltage. These would interact with the Galactic magnetic field, swinging the LPV around in a slow, giant arc (Figure 17.4a). The course is chosen to aim back through the target star system, but on a general heading towards Earth. The wires are discharged and reeled in; the orbital laser network is turned on again, this time functioning to decelerate the starcraft.²⁷⁵⁶

Very large space-based laser arrays would be required to carry out such a mission, perhaps as big as 250 kilometers in diameter. These should be parked in close solar orbit, drawing their power directly from the high solar flux available there. For maximum efficiency, the LPV’s mirrored "sail" should be of a size comparable to that of the laser array — perhaps 250 km wide, weighing thousands of tons even if it is very thin. Surprisingly, the laser array energy flux need not be very high to push a vehicle to relativistic speeds. Typically the beam should be no more powerful than ordinary sunlight.

A proposed hybrid system combines the best qualities of the interstellar ramjet and the laser pushed vehicle and avoids many of their disadvantages. Called the Laser Powered Ramjet, or LPR, the starcraft obtains its power from a space-based laser network and its reaction mass from the interstellar medium using an electromagnetic ramscoop. The propulsion system is greatly simplified because the LPR does not require an onboard hydrogen-burning fusion reactor motor — since all power is furnished by laser beam. Calculations suggests that the LPR may be superior to the LPV under virtually all conditions. It should also outperform the Bussard ramjet at speeds below 14%c during the acceleration phase and
at all speeds during the deceleration phase of the mission.²⁷³³

Whitmire and Jackson propose two additional alternative propulsion systems that appear promising. The first of these is the Laser Powered Rocket, which differs from the LPR because it carries along its own reaction mass onboard instead of gathering it from the interstellar medium. Extraordinary energy efficiency may be possible because the exhaust velocity is controllable.²⁷³³

The second possibility may be called the Particle Powered Ramjet, which obtains its reaction mass, its fuel, or both from space-based particle accelerators: After acceleration, the particles could be neutralized by the addition of electrons or positrons to avoid coulomb spreading of the beam. The neutral particle current required would be relatively modest — for antimatter, about 10⁵ amps to produce 10¹⁴ watts on board at low velocities. The problem seems to be collimation since there is no particle analogue to the laser.²⁷³³

Table 17.4 Black Hole Power Generation and the Spontaneous Evaporation of Hawking Black Holes

The basic idea of using antimatter to power starships has been discussed in the technical and fictional literature for many decades. The most common system is the "photon drive"*: Simply bring together equal quantities of matter and antimatter, allow annihilation or "total conversion" to take place, and then convert the products to useful thrust. Gamma rays as well as high energy electrons and positrons are thrown off, but about half of the energy liberated is in the form of neutrinos which escape isotropically and are wasted.

The usual antimatter propulsion scheme thus amounts to no more than "partial conversion" with an efficiency well below 50%. Better results may perhaps be obtained by using cold or "frozen" positronium gas as fuel. Positronium consists of pseudo-atoms in which a negatively charged electron orbits a positively charged positron (the electron’s antiparticle) — this has been observed experimentally. As the fuel is warmed, electron and positron annihilate, producing a pure beam of gamma radiation. Eugene Sänger proposes using an electron gas reflector to focus and direct the photonic jet.²⁸⁴⁰ Alan Bond estimates that a million-ton starship with a mass ratio (fueled/unfueled, by weight) of 7.4 and an acceleration of one gee could reach 60%c.¹¹⁵⁹

Dr. D.D. Papailiou at Jet Propulsion Laboratory in Pasadena claims that for missions to nearby stars optic exhaust velocities are not necessary. A far more efficient technique is to use a small amount of antimatter to energize a large amount of ordinary matter. Preliminary calculations by Papailiou show that a mass ratio of 5.0 and a 2% charge of antimatter (by weight) is optimal to achieve a probe coast velocity of 33%c.²⁷⁵⁷

So if we wanted to launch a 10-ton starship on an encounter-capture mission, we must built a top stage of 51 tons — the 10-ton probe, 40 tons of ordinary matter, and 1 ton of antimatter — to obtain a mass ratio of 5. This stage serves to decelerate the probe at its destination. To get it there, we will need a 205-ton bottom stage — 200 tons of ordinary matter and 5 tons of antimatter — in order to accelerate the top stage up to 33%c. Delivery of a 10-ton space probe with a coasting speed of 33%c to another star system thus requires a total ship mass of about 256 tons, of which 6 tons are antimatter.

A related scheme is the Antimatter Ramjet, which gathers normal matter in the forward scoop primarily as reaction mass. In a manner similar to Papailiou’s antimatter drive outlined above, interstellar matter would be commingled with bits of antimatter stored onboard. In this case the probe need only carry the requisite 6 tons of antimatter fuel when it leaves the planet of origin (perhaps stored in the form of frozen antihydrogen maintained a few degrees above absolute zero), and can pick up the remaining 240 tons of ordinary matter en route to its destination.

Many physicists object to the feasibility of total conversion drives such as those mentioned above because of the difficulty today of generating macroscopic quantities of antimatter. But the problems of creation and control should not prove insuperable. Writes Dr. Forward:

The present methods for producing antimatter involve the use of large accelerators which can produce a proton beam of 10¹⁵ protons per second. When such a beam collides with a target, antiprotons are produced as part of the debris. The antiproton yield of present machines is very low. However, the presently used methods are not designed for antimatter production but rather for studies in the physics of elementary particles. Rough calculations assuming special purpose high amperage colliding beam accelerators indicate that the generation of kilograms of antimatter per year is not out of the question. The containment and control of the antimatter, once made, should not be too difficult since we have a number of ways of applying forces to the antimatter without touching it. Electric fields, magnetic fields, rf fields and laser beams are all used in present day technology to levitate and control small amounts of regular matter that we do not want to contaminate. These would all be equally effective on antimatter.⁷¹⁸

Another considerably more speculative total conversion system involves so-called Hawking Black Holes (HBHs). According to Dr. Stephen H. Hawking at the University of Cambridge, all black holes (if any exist) radiate energy due to quantum mechanical "tunneling" effects. This is equivalent to mass loss, so eventually the entire corpus of the black hole "evaporates." A stellar-mass BH is very "cold" — in fact, close to absolute zero — but a low-mass HBH is extremely "hot" and prone to explosive evaporation.²⁰²¹ For instance, a million-ton HBH should radiate about 10¹⁸ watts at a temperature of about 10¹⁵ K, and will take about one year to finish evaporating.

The HBH becomes a total conversion engine when we start "feeding" it. Evaporation can be indefinitely postponed simply by shoveling in raw matter — any matter — at an appropriate rate (Table 17.4). Such a device could be used to construct an extremely high-efficiency photon drive propulsive system. The main problem is how to construct an HBH in the first place. Dr. John A. Wheeler estimates that a black hole of mass 10⁹ kilograms might be generated artificially by the controlled thermonuclear fusion implosion of approximately 5 × 10¹³ kg of deuterium.²⁰²² This involves the handling of some 5 × 10²⁸ joules of energy, which looks like a job for an ambitious mature Type II civilization or an early Type III galactic society.

* Acceleration A (m/sec²) of a perfect photon rocket of mass M (kg) and power output P (watts) is given by: A = 2P/Mc, where c is the speed of light (3 × 10⁸ m/sec).

The exotic interstellar propulsion systems discussed in this section are all at the "idea" stage in human technological development. There is no guarantee that any or all of them can be made to work. A few have some theoretical support, but many do not.

Nevertheless, xenologists deem them important because of the likelihood that some may have advanced to the "profit" stage of exploitation in at least a few extraterrestrial Type II or Type III technological civilizations.

It is possible to conceive of "machines" that are capable of pushing a body, using gravitational force, up to fairly impressive suboptic velocities. These devices violate no known basic laws of physics, but it's difficult to see how to do the required engineering.

The most "conventional" of these, first discussed by Freeman Dyson, has been called the Contact Binary Catapult.¹⁰²³ A starship approaches a binary star system whose members are both white dwarfs orbiting each other at close range. By swinging in very near to one star on the proper trajectory, the starcraft benefits from gravitational slingshot or Newtonian "gravity whip" effect. The vessel withdraws orbital energy from the stellar pair.

Dyson estimates that a system involving two 1 Msun white dwarfs could accelerate delicate and fragile objects to a velocity of 0.7%c — at about 10,000 gees. Since there are no engines or propellants, there are no physical stresses on the payload — gravity acts on all parts of a material body equally. (Tidal forces, on the order of D/80 gees where D is starship diameter in meters, should not prove troublesome.)

Dyson also considered the possibility of using a pair of orbiting neutron stars as a gravity catapult. Unfortunately, they cannot exist! A neutron star binary would radiate away all of its orbital energy as gravitational radiation in less than 2 seconds. The two objects would coalesce almost immediately with a spectacular "gravity flash" at a frequency of about 200 Hz.

A more exotic technique is the Black Hole Catapult. This scheme requires that and find a rotating black hole (stellar mass) somewhere in space, then travel around it in the direction of spin very near to the equator. Besides losing a lot of time because of General Relativistic time dilation effects, some of the BH’s rotational energy would be converted to linear kinetic energy of the star ship. There would be a substantial increase in velocity. Tidal forces during transit will be rather extreme — about 500 million gees per meter — but apparently there are tricks with dense masses in a space vehicle that can be used to cancel the tides.²⁰¹⁴ A Neutron Star Catapult is also possible, with similar effects.¹⁰⁹⁹

The most speculative gravity machine of all is the Smoke Ring Catapult, which consists of a rotating torus of dense matter (such as neutronium) turning inside out like a smoke ring.²⁷³⁹ Relativity theory predicts a force in the direction of the rotation, so a starship fired through the center of the massive hoop could be kicked up to very high velocities — depending upon the rotational energy of the torus.

Over the years the theme of antigravity and inertialess propulsion systems have been widely discussed, mostly in the fictional or pseudoscientific literature.

• From H.G. Well’s cavorite gravity screen in his First Men in the Moon,
• To such questionable propositions as the Biefield-Brown effect,¹³⁷
• Blackett’s Spin-Magnetic Coupling Theory¹¹⁹⁴ (which apparently inspired the late science fictioneer James Blish to write Cities in Flight with its "spindizzy drive"²⁸⁰⁹),
• F. B. Hli’s Theory of Electrogravitics (see the lively debate in Cashmore and Gordon,^1197,1199 Hli,¹¹⁹⁶ Hli and Okress,¹²⁰¹ Johnson and Hli,¹¹⁹⁸ and Okress¹²⁰²),
• Leonard G. Cramp’s G Field Theory,⁷⁵⁵
• And of course the infamous Dean Drive (see Adams,²⁸⁵⁹ Campbell,¹³⁶¹ Cuff,²⁷⁷³ Davis,¹³⁷¹ Jueneman,²⁸⁰⁷ Klotz et al,²⁷⁷² Pournelle,²⁸⁰⁶ and Stine²⁷⁷¹), the idea has enjoyed a colorful and vituperative history.
• A number of U.S. patents have been issued on supposed antigravity machines.²⁷⁷³
• Even Einstein himself spent the last thirty years of his life searching for a unified field theory that would relate gravity and electromagnetism, and the search continues apace today.²⁷⁷⁴

To construct a gravity screen would theoretically require the ability to achieve gravitational polarization of matter.¹⁶ This would imply the existence of two very different kinds of matter — positive mass, which is attracted towards the Earth, and negative mass, which is repelled. At one time it was believed that antimatter might turn out to have negative gravitational mass,²⁶⁹² but most physicists would dispute this today.^1314,2952

Yet the search for negative mass continues. So far as we know there is no experimental evidence for negative matter, although it does appear in several solutions to the field equations in General Relativity. Papers by A.K. Raychaudhuri¹⁵²¹ and R. Mignani and E. Recami¹⁵¹⁹ suggest that tachyons may experience a gravitational repulsion to ordinary mass and thus may be interpretable as "negative matter," although because of their imaginary masses they will still fall towards a positive mass.

Besides gravity shields, negative masses, if they exist, could be employed directly for propulsion. A negative mass at rest beside a positive mass would begin to accelerate. Why should this be so? The negative mass (which repels all matter) would push on the positive mass, but the positive mass (which attracts all matter) would pull on the negative mass¹¹⁹⁰ If the two objects "weigh" the same, they will chase each other and will neither separate nor collide. Energy and momentum is conserved, since they each sum to zero.

Presumably the negative mass could be created out of empty space if a positive mass of equal "weight" was created simultaneously. The net energy cost would be zero, since (-m)c² + (+m)c² = 0. To achieve reasonable starship accelerations, compact masses with densities like black holes should be used. Dr. Robert Forward elaborates:

What we really want to do is make a dense negative mass and a dense positive mass down in the engine room. We’d just pull them out of empty space, put a charge on the positive one and couple it with the spacecraft with electric fields. Now we have the two masses down in the engine room; they’re probably about 10^-23 cm across and they weigh a little more than the spacecraft. The positive one is coupled to the spacecraft and the negative one pushes the positive one which pushes the spacecraft. Our vehicle’s acceleration can be as high as we can tolerate.²⁰¹⁴

A related concept is the idea of inertia control. Gravitational mass represents the force of gravity, and inertial mass represents the force of physical acceleration. The Eotvos experiment demonstrated that the two kinds of mass are identical out to eleven decimal places, under normal terrestrial conditions. But suppose we (or clever aliens) could arrange abnormal conditions which would allow the inertial mass of a chunk of matter to vary. When inertia is decreased, the same force imparts a higher acceleration; as inertial mass is brought close to zero, tiny forces would be able to produce huge accelerations. Lowering the inertial mass of fusion rocket propellant tanks would eliminate most of the normal constraints on lengthy interstellar missions for such vehicles.

Figure 17.5 Three Possible Antigravity Machines2014 Special General Inertia Redistribution Special Relativistic Antigravity Machine Newton’s law of gravity does not obey Special Relativity. However, a "linearized" version of Einstein’s gravity theory (General Relativity) does. In this version, a mass flow gives rise to a "protational field" much as a charge flow gives rise to a "magnetic field" in conventional physics. This is called the "Lense-Thirring Effect." The Special Relativistic Antigravity Machine is a torus wrapped in helical tubing. A dense mass flow is rapidly circulated through this tubing, causing a protational field to arise along the circumferential axis of the torus. Just as a changing magnetic field generates an electric field, a changing protational field should generate a unidirectional gravity field. This field, directed upwards, would cancel planetary gravity and provide vertical propulsion. General Relativistic Antigravity Machine According to Einstein’s General Relativity theory, the presence of mass in a flat spacetime will cause that space to become curved. Mass is intimately connected with space — a rotating mass causes spacetime to "rotate" too. The General Relativistic Antigravity Machine consists of a torus of dense mass which is turning inside-out like a smoke ring. A mass with this motion, according to Einstein’s theory, "drags the metric" through the center of the torus. Unidirectional general relativistic forces arise which are equivalent to gravity, and may be used to neutralize planetary surface gravity or as a space propulsion system. Inertia Redistribution Antigravity Machine While not widely accepted by theoretical physicists, there is a theory that the inertia possessed by all matter is a "tensor" quantity — that is, a multidimensional vector. In other words, inertia is not just a simple quantity but rather must be measured in the three separate directions of normal space. The Inertia Redistribution Antigravity Machine does not destroy inertia or convert it into energy, but merely redistributes it in different directions. The starship to which the device is attached becomes "heavier" in the horizontal plane (thus imparting navigational stability) and "lighter" in the vertical direction. An object with minuscule inertial mass in one direction can be accelerated to fantastic velocities with negligible force.

Three other antigravity machines have been discussed by Robert Forward which involve no violations of the basic and established laws of physics (Figure 17.5).

The first of these, which he calls the Special Relativistic Antigravity Machine, involves a mathematical analogy between gravitational and electric fields.²⁷⁴⁰ A "linearization" of General Relativity gives a version of Newtonian mechanics which obeys Special Relativity. (Classical Newtonian mechanics does not.) In electromagnetism, something called charge is surrounded by a spherically symmetric electric field. In gravitation, something called mass is surrounded by a spherically symmetric gravity field. It may be said that the simple Newtonian gravity field is the gravitational analogue to the electric field.

The linearized General Relativity theory provides a similar analogy to magnetic fields. Much as a magnetic field is due to the motion of an electric charge or current flow, the linearized theory suggests that a moving mass, or "mass current," will give rise to a new kind of gravity field by a mechanism known as the "Lense-Thirring Effect."²⁸⁹⁰ Scientists plan to try to measure this field as it is produced by the rotating Earth in future satellite experiments.³³²⁰

Forward calls this new field a "protational field." He claims that, based on the existence of the field, an antigravity machine might theoretically be constructed in the shape of

…a torus with a tube wrapped around it, filled with very dense matter. If we started accelerating that mass flow through the tube around the torus, we would get a constantly increasing protational field, inside the torus. A changing protational field will create a gravity field just as a changing magnetic field will create an electric field. If we did it right, we would have an upward gravity field that could be used to cancel the field of the Earth.²⁰¹⁴

A second kind of antigravity machine suggested by Dr. Forward couples directly to "the fabric of space-time." His General Relativistic Antigravity Machine makes use of the notion that the presence of mass in a flat space-time causes a curvature, and that a rotating mass causes space-time to rotate too:

Imagine a rotating torus of dense mass, turning inside out like a smoke ring. An inside-out turning ring of very dense mass will create a force in the direction of the motion — a "dragging of the metric" as it is sometimes called. There will be general relativistic forces in the direction of the velocity of the mass. These forces are equivalent to a gravity field which again, theoretically, can be used to cancel the gravity field of the Earth.²⁰¹⁴

And, as Willy Ley once pointed out, such a weightless body "would be squeezed out of the atmosphere by the weight of the air around it."²⁸⁰⁸

Finally, there is the Inertia Redistribution Antigravity Machine. The main principle behind inertia redistribution is the idea that inertia is a "tensor" quantity.²⁷⁴⁰ A tensor is just a multidimensional vector, so all this means is that we are accepting for the sake of argument the hypothesis that inertia may be a quality of matter that can be resolved into distinct directional components. That is, in our normal three-dimensional world, inertial mass becomes a three-dimensional quantity. While current experimental evidence does not support the tensor theory of inertia, if it is correct it leads to an interesting possibility for propulsion.

The Redistribution Machine does not get rid of inertial mass, but rather redistributes it so that some of it is pointing in new directions. If the machine makes the starship’s mass heavier in the horizontal plane and proportionately "lighter" in the vertical direction, a relatively tiny amount of force applied vertically would cause relatively large accelerations in that direction. The benefits are similar to those achieved using inertia control, discussed above, with the added advantage that inertia is conserved. (Note that since gravitational mass is unchanged, spacecraft will still feel the same attraction to planets and other massive bodies.)

Inertialess starships would have a number of interesting performance characteristics. Such a system must necessarily act upon every atom of the vessel in order to be effective. Far from any planet (so gravitational mass can be ignored), the inertialess craft could start and stop almost instantaneously. Since passengers have almost no inertia in the direction of flight, hideous accelerations can be tolerated (in that direction) with equanimity. For instance, if vertical/forward inertia is cut to 1% of normal and the ship accelerates at 100 gees, passengers would feel only an effective 1 gee of force. Inertialess starcraft would be virtually crashproof, since with no forward inertia people would not be thrown from their seats if an obstacle was struck. And, depending on how fast inertia can be suddenly redistributed, right-angle turns and hairpin bends should also be quite possible.

We have already mentioned the possibility of using tachyons for faster than-light communication. But could aliens use them for FTL space travel too?

Gerald Feinberg of Columbia University has divided all matter into three general classes:

• Tardyons — particles which can move at any velocity less than the speed of light (normal matter)
• Luxons — which can travel only at 100%c (photons and neutrinos)
• Tachyons — particles restricted to superluminal velocities¹⁴⁹²

All three classes may exist on the basis of Relativity theory.

If we desire to travel at hyperoptic velocities and achieve "true" FTL, somehow our starship must be converted from tardyon matter into tachyon matter at the start of the journey and then back again at the destination. While "conversion" may sound a bit like magic, actually it violates no laws of physics to presume it can be done. In fact, such conversion between classes of matter, to a limited extent, has already been verified experimentally.

Of course, no tachyons have been discovered yet. But nuclear physicists long have known that an electron and a positron, both tardyons, undergo "annihilation" when brought together with the release of two or three gamma-ray photons, which are luxons. Another example is the decay of the neutron, a tardyon, into among other things an antineutrino, which is a luxon. Still another example is "pair production," in which a gamma-ray (luxon) striking an atomic nucleus gives rise to an electron/positron pair (both tardyons). Conversion between tardyons and luxons, and back again, may be regarded as a verified physical phenomenon. There would seem to be no theoretical objection to conversion from tardyons to tachyons and vice versa, although the process may have to be moderated by luxon intermediaries.

The real technological trick will be to discover a procedure for interconversion which leaves undisturbed the essential molecular relationships upon which life and physical structure are based. Dr. Gregory Benford, nuclear physicist and science fiction writer, has suggested one highly speculative possibility in his story "Seascape":

In the laser the problem was simply to produce a coherent state — to make all the excited atoms emit a photon at the same time. Okawa reasoned that the same problem appeared in the faster-than-light drive. If all the particles in the ship did not flip into their tachyon states at the same time, they would all have vastly different velocities and the ship in one grinding instant would tear itself apart. Okawa’s achievement lay in finding a technique for placing all the ship’s atoms in excited tachyon states so that they could all be triggered at the same instant; the particles of the ship Jumped together, coherently. … All this was accomplished by maximizing the cross section for transition from real particle to tachyon. Complex modulated electromagnetic waves controlled the transition through microelectronic components, which operated on the scale of atomic dimensions.

Another conversion technique involves the use of the concept of quantum mechanical "tunneling." Quantum mechanics predicts that it is possible for particles to pass through energy barriers which would otherwise be "too high" for them to surmount. (This, in fact, is Hawking’s explanation for the evaporation of black holes.) Using the tunnel effect, a particle with insufficient energy to pass "over" a barrier instead passes "through" it. This peculiar behavior has been verified in the laboratory, and is exploited in modern electronic devices (e.g., tunnel diodes) as components in computer circuits.

Presumably, if we can get up close enough to the lightspeed barrier, it may be possible to "tunnel" across into tachyonland. The starship will then have to lose energy to go faster.

A third technique for achieving superluminal tachyonic starflight has been suggested by Dr. Forward. Mathematicians have long known that certain wave phenomena can be represented by "complex numbers." A complex number is a two-dimensional quantity, having a real dimension and an "imaginary" dimension. (Recall our earlier discussion of the imaginary mass of tachyons.) Electronics engineers regularly use complex numbers to describe the behavior of alternating current (AC) circuits.

If physical mass can be represented mathematically as a complex "something" in "mass space," then objects in that space may be able to rotate to new orientations along the real and imaginary coordinate axes. Since tachyons have imaginary mass, a full 90^o rotation would correspond to a conversion to tachyons. Says Forward:

Since we want the mass to be imaginary, we would have to get our spaceship off the real-line in that complex space and onto the imaginary-line. This would require that we make a right angle turn in mass space. When we do that, our ship becomes a tachyon.²⁰¹⁴

Finally, what would tachyonic astronauts see during their hyperoptic journey? The tardyon and tachyon universes seem to possess symmetric equivalence, an intuitive observation borne out by careful mathematical reasoning.²⁷⁷⁰ Consequently, travelers in tachyonland should observe what appears to be another tardyonic universe (assuming there is as much tachyonic mass as tardyonic mass in all the cosmos). That is, a tardyon starship moving at 50%c in our universe which suddenly converts into tachyons will be traveling at an effective 200%c relative to our universe; but in the tachyon regime, where the vessel really is, it will still appear to be moving only at 50%c.

Terran scientists already know that electricity and magnetism are interchangeable, based on the work of James Clerk Maxwell in the 19th century. Mass and energy are too, according to Albert Einstein, as well as space and time. It is not unreasonable to hypothesize that angular and linear momentum may be similarly related.

If such interconversion were possible, theory has it that some fundamental physical constant would be required, having the dimensions of length, to balance the mathematical equation involved. According to John Wheeler,²⁷⁴¹ one of the fundamental constants of nature is the Planck length, written Λ, based on the Planck constant (h), the universal gravitation constant (G), and the speed of light (c).*

Robert Forward suggests that if we use the Planck length a suitable interconversion formula may be derived: Angular momentum (L) equals linear momentum (p) times the Planck length, or L = pΛ. Using this purely hypothetical relationship, it is simple to calculate that the destruction of a unit spin from a single tiny atom (about 10^-34 kg-m²/sec) would yield 6.6 kg-m/sec of linear momentum. This means 6.6 kilograms of mass moving at 1 meter/second. The interconversion of only 45 billion atoms — about 0.1 picograms of hydrogen — would thus be sufficient to propel a 100-ton starship at l%c.

The above scheme, of course, requires the violation of conservation of linear and angular momentum. This difficulty may be made somewhat more palatable in the following way. Physicists recognize that the source of gravity in General Relativity theory is what is called the "stress-energy-momentum-mass tensor." That is, mass alone isn’t the only source of gravity. Kinetic energy, stress energy, linear and angular momentum also contribute to the field.

We already know that mass and energy can be interconverted, according to the relation E = mc². It may turn out to be possible to interconvert everything in the stress-energy tensor, perhaps according to an equation like E = mc² = pc = Lc/Λ. Vast amounts of propulsive energy would become available. Says Forward:

If we took one unit of spin which is 10^-34 units of angular momentum (very small), we would get 6.6 kg-m/sec of linear momentum or 10^-8 kg of mass or, equivalently, 10⁹ joules of energy — all from one atom.²⁰¹⁴

* The formula Wheeler gives is: Λ = (hG/2πc³)^1/2 = 1.6 × 10^-35 meters.

The mysterious, often apparently "magical" results of modern quantum physics have enticed many writers to try their hand at devising propulsion systems based on the principles of quantum mechanics and statistical thermodynamics. Most of these fall reliably into two general categories: Bootstrap Drives and Heisenberg Drives.

To visualize a Bootstrap Drive, consider a cylindrical vessel filled with ordinary gas. Although each of the molecules is rushing madly about at speeds in the kilometer/second range, the net effect of trillions of particles darting in random directions is a wash-out. The molecule motions are averaged out over the walls of the container, yielding a net system velocity of zero.

About half a century ago, the late John W. Campbell, Jr. suggested that it might be possible to devise an external field that would induce the molecules subject to its influence to assume the highly improbable state of collective upward motion.¹¹¹⁰ Much of scientific experimentation involves the judicious rearrangement of probabilities to achieve desired results, so this idea is certainly not impossible. The result would be a reactionless Bootstrap Drive that could be used to propel spaceships to other worlds.

It is fairly clear that the technology to achieve a bootstrap effect will not be trivial. The magnitude of the difficulty may be made plain with a fairly simple example. Imagine a pan containing a liter of water, placed on a stove that can bring it to a full boil in 15 minutes. Our experiment consists simply of heating the liter of water to the boiling point over and over again. According to the laws of statistical thermodynamics, there is a very small but nonzero probability that during one experimental cycle the molecules will spontaneously arrange themselves in crystalline form — that is, freeze instead of boil. But calculations show that this event is so improbable that it is expected to occur only once in every 10^{10,000,000,000,000,000,000} years, assuming 15 minute cycles. Clearly, to enhance such miniscule probabilities will not be easy.

But if it could be done, the Bootstrap Drive would permit a container of gases to move on its own without the ejection of any reaction mass. The ship would rise up, so to speak, by tugging on its own bootstraps. In normal operation, the Bootstrap Drive would give up thermal energy and become very cold. To maintain the propulsive force, it should be necessary to supply additional energy to the system in the form of heat.

In the 1940s Campbell also came up with a number of starship propulsion system designs operating on Heisenberg’s Uncertainty Principle in quantum mechanical theory. Arthur C. Clarke describes the functioning of the Heisenberg Drive:

In the Uncertainty Theory, a particle cannot be said to have a fixed position in space but has a very small, though finite, probability of being anywhere in the universe. All you had to do, therefore, to get an instantaneous mode of transport was to manipulate the Heisenberg equations until you were more likely to be somewhere else than where you started, and — presto!¹¹¹⁰

In essence, starships using the Heisenberg Drive "move" by going from maximum probability of existence at one position in the universe, through universality, to maximum probability of existence at another position elsewhere.²⁶⁴²

Figure 17.6 Using Black Holes for Interstellar Travel Wormhole Rotating Black Holes Folded diagram The Wormhole In the Einstein-Rosen model of the nonrotating black hole, a wormhole connects portions of two separate flat-space-time universes. This wormhole, called the Einstein-Rosen Bridge, may be interpreted either as connecting two distinct universes or as joining two distant points in the universe of origin. According to this theory, starships passing through the event horizon of a black hole would find the curvature of space-time growing less severe, eventually emerging through a "white hole" in distant space.2954 The diagram on top shows the Einstein-Rosen Bridge as it might connect two distant points in the same universe. The event horizon lies at the center of the wormhole. The diagram on the bottom is an "unfolded" version of the Bridge, for those who would rather view universal space-time as essentially flat. The two are mathematically equivalent Kruskal Diagram for Rotating Black Holes The figure at right represents a possible space-time configuration of a rotating black hole, using "Kruskal coordinates." There are now two event horizons instead of one, so there are three classes of space./p> It is possible to reach other universes like ours by selecting the correct trajectory upon entering the black hole. (Trip C) A collision with the ring singularity is possible. (Trip B) Cowardly astronauts can avoid the black hole altogether. (Trip A) Some "Type I" universes cannot be reached at all until tachyonic star travel is permitted .(Trip D) Folded Kruskal diagram The Kruskal diagram of the Kerr solution to the equations describing rotating black holes may be folded cylindrically as shown in the diagram at right. Using this interpretation of the wormhole caused by a rotating BH, a starship is theoretically capable of circumnavigating the entire Kruskal space-time and returning to the universe of origin anywhere in space and anywhen in time. This would appear to violate causality and permit time travel.

Severe gravitational distortion of space-time offers several scientifically plausible mechanisms for extremely fast interstellar communication and travel.²⁷⁹⁸ Dr. John A. Wheeler of Princeton University has predicted the existence of "wormholes" — a warpage of free space — based on his own version of General Relativity which has come to be known as geometrodynanics.²⁷⁴¹

Wheeler wormholes should be exceedingly small (subatomic dimensions, say, about 10^-35 meters). They would allow point-to-point linkages of all locales in the universe; pointlike particles, such as electrons, could be used to communicate without traversing the intervening space. Wheeler draws an analogy to the sea:

Space is like an ocean which looks flat to the aviator who flies above it, but which is a tossing turmoil to the hapless butterfly which falls upon it. Regarded more and more closely, it shows more and more agitation, until … the entire structure is permeated everywhere with worm-holes Geometrodynamic law forces on all space this foam-like character.⁷⁷

J.C. Graves and D.R. Brill at Princeton have shown that electric field lines threaded through the throat of a wormhole may prevent it from closing.²⁷⁷⁷ Such a tunnel in space should stay open indefinitely, allowing particles of matter to pass through to known destinations. Wormholes may connect a vast number of alternative universes at the subatomic level.²⁷⁷⁸

Black holes, predicted in 1939 by Oppenheimer using General Relativity theory, are concentrations of mass so dense that even light cannot escape the tremendous gravitational pull. Stellar-mass BHs are typically several kilometers in diameter. The standard black hole model predicts a "singularity" at dead center, a point at which density becomes infinite, This collapse of physical laws as we know them, fortunately, is hidden from view behind an event horizon — the surface below which photons cannot escape.

However, in the case of a rotating black hole things are quite different. According to relativistic solutions first obtained by R.P. Kerr in 1963, the singularity is no longer a point but has expanded into a ring.²⁷⁴² Many theorists believe that the region lying in the disk of the ring singularity may be a gateway to other universes or to our own universe at a different point in space and time. Rotating BHs have two event horizons instead of one, passage through which by a starship may involve such peculiar phenomena as negative mass effects and time running in reverse.²⁷⁴⁶ The Kruskal Diagram illustrated in Figure 17.6 shows one interpretation of possible trajectories through a rotating black hole assuming a Kerr spacetime metric.²⁷⁴⁷

A few writers have offered fabulous accounts of galactic commerce among sentient extraterrestrial races, using black holes as the entry gates to a kind of hyperspatial subway system.* Says astronomer Carl Sagan:

I can imagine, although it is the sheerest speculation, a federation of societies in the galaxy that have established a black hole rapid-transit system. A vehicle is rapidly routed through an interlaced network of black holes to the black hole nearest its destination. … Great civilizations might grow up near the black holes, with the planets farthest from them being designated as farm worlds, ecological preserves, vacations and resorts, specialty manufacturers, outposts for poets and musicians, and retreats for those who do not cherish big city life. In such a galaxy the individuality of the constituent cultures is preserved but a common galactic heritage established and maintained. Long travel times make trivial contact difficult, but the black hole network makes important contact possible.¹⁵

There are a number of practical difficulties associated with the use of BHs as an interstellar rapid-transit system. First, there is the problem of navigation. Until you jump into a black hole, you don’t really know where you will end up. Once you emerge at your destination (from a "white hole"), it is difficult to know how to get back. Many theories predict that it may be impossible to return. If you have entered another universe, the journey is probably irreversible and strictly one-way; if you have remained in your own universe, it would be an extraordinary stroke of luck to find another rotating BH in the immediate vicinity whose exit terminus happens to lie near the original starting point.

Tidal forces are yet another problem. Astronauts venturing even within a few hundred kilometers of a stellar-mass black hole would be savagely ripped apart by the simultaneous squeezing and stretching forces which would amount to hundreds of gees. While it may be possible to compensate for these effects by using special arrangements of ultradense matter within the starship structure, it may be better instead to search for supermassive black holes. Several theoretical physicists have proposed that gigantic BHs may exist at the center of many galaxies — possibly even our own — with masses ranging from 10⁶-10¹⁰ solar masses. Surprisingly, such monstrous objects need be no more dense than air, and tidal forces would be measured in milligees rather than megagees at the event horizon.

Catastrophe theory, first devised by French mathematician Rene Thom more than a decade ago,²⁸⁰⁰ offers a totally new conceptual variation on the theme of space warp drives. Catastrophe theory is a controversial new mathematical tool for examining highly discontinuous events — such as bridges buckling, sudden economic depressions, rapid emotional changes from fear to rage, and a host of other abrupt alterations in physical structures, lifeforms, and societies. The theory explains how slight changes in the initial state of a system can result in major divergence in the course of its evolution and subsequent behavior.

Since the Big Bang was a highly discontinuous event, creating a universe out of nothingness, it is quite conceivable that a catastrophe cosmology may eventually be devised. Perhaps it would involve catastrophe surfaces rather than simple spherical space-time geometry. Indeed, the coordinates need not all be spatial or temporal, but could include axes representing energy, momentum, spin, mass, charge, angular velocity, or whatever else is appropriate. If this is so, then the proper combination of fields and physical parameters could cause a packet of photons (a message) or a chunk of matter (a starship) suddenly to assume new parameters in a single, "catastrophic" leap. These new parameters might correspond to changes in energy, spatial position, or time.

* We will not here discuss the fascinating possibility of tachyonic black holes, although these have already been investigated theoretically.¹⁵²⁰

The first type of matter transfer system we’ll consider may be called the Teleportation Booth. To travel, the subject is seated in the transmission chamber. Complete data on the composition, position, and energy states of each atom in his body are read out by means of a sophisticated scanning device, and recorded in computer memory. The original may or may not be destroyed. The data is transmitted at the speed of light (radio waves) or faster (using tachyons) to a distant receiver, which picks up the data and places it in the memory banks of a second computer. A new human body, an exact duplicate right down to the last atom, is then reconstructed using the information taken from the original. The replica emerges from the booth, indistinguishable from the original in every way.*

If you think about this scheme, what has been accomplished here is not true matter transmission but rather transmission of information about matter. There is nothing fundamentally impossible about this process. In fact, in one dimension — sound — the problem may be regarded as solved by human technology. With the very finest audio equipment, duplicated sounds can no longer be distinguished from the original variations in air pressure that caused them. Further, these "replicas" can be transmitted over vast distances by radio waves.

Television represents the solution in two dimensions. In a typical system, a sophisticated TV vidicon scanner reads the information from the surface of, say, a human face, transmits the data to distant receivers, and the image is reproduced on the picture tube. Admittedly the visual reconstructions are far from perfect, but the electronics engineers are busily working to correct that defect.

Figure 17.7 Teleportation Booths: Precursor Technology on Earth Biostereometrics CAT Scanner X-ray Holography Biostereometrics Biostereometrics is a new scientific discipline which allows the three-dimensional measurement of living things using techniques similar to aerial mapping. The figure at right is the result of a low-resolution computer-generated optical replica of a male human body. The data stored in the computer may be used to rotate the replica to any angle or position, or to "dissect" the figure and examine any single part in greater detail.2835 CAT Scanner As for the present state-of-the-art in examining the insides of human bodies, the "CAT Scanner" is about the best there is. Essentially an automated x-ray machine, the Scanner looks at the body in very thin slices and can detect variations of only a few percent in transmitted intensity. The photos BELOW are a Scanner record of a human female across the chest area, showing the spine, aorta, and even a small pancreatic cyst just to the right of the spine and aorta.2835 X-ray Holography At right are the first direct images of atoms of magnesium, oxygen and carbon in a section of crystal, using a technique called x-ray holography in conjunction with a digital computer system.2810

The Teleportation Booth is the answer to information transfer concerning three dimensions. It operates in such a manner as to transmit a 3-D image through space. As with radio and television, the original goes nowhere.

It is entirely possible to imagine the construction of the Booth by making a direct extrapolation of currently-foreseeable human technology (Figure 17.7). Our present techniques of x-ray diffraction scanning, neutron-beam crystallography and field-ion microscopy easily permit resolutions at the atomic level (say, 1 Angstrom),^419,2801 and subatomic scanning is already available using large cyclotrons and linear particle accelerators. Indeed, high energy neutrino beams have been used to examine details of subnuclear structure as small as 10^-18 meter, or about 0.00000001 Angstroms.²⁸²⁵

How about computer memory? Ten terabit (10¹³ bits) memories are already available for use in Booth construction.⁵⁸³ Will this be enough? The human body consists of roughly 3 × 10²⁷ atoms, so at first blush we might expect that at least 10²⁸ bits of information should be needed to completely specify the human transmittee. Fortunately, the vast majority of these data are redundant. Our genes, a considerably more compact specification or "blueprints" for our bodies, represent only about 10¹⁰ bits. Our brains, however, contain at least 10¹³ bits of information — so this turns out to be the limiting factor.

According to Tim Quilici of Collins Telecommunications Systems Division of Rockwell International, a fairly new technique called electro-optical modulation may soon permit transmission rates through space of 10¹⁰ bits per second per channel.²⁷⁷⁹ The information detailing the construction of the human body thus could be completely transmitted, perhaps using a 1 mm infrared space-based laser beam, in just one second — although it would require another twenty minutes for the subject’s entire brain-map to arrive, if only one data channel is utilized.

Once the information has been received, the subject could be physically reconstituted using an extended and more exact version of the present-day techniques of molecular beam epitaxy, electron beam microfabrication, or some similar process.²⁸⁰⁴ The living subject would probably have to be assembled cold, close to absolute zero dissociative and degenerative chemical reactions, and would later be warmed and reanimated. It would seem that the Teleportation Booth is a great way to scatter copies of one’s self throughout the universe or across a planet, but it is a lousy way to travel — because you don’t go anywhere.**

Booth technology would also make possible a device which Arthur C. Clarke has called the Replicator.⁵⁵ The Replicator has access to a vast library of information which specifies all known physical objects and consumer goods, and is able to reproduce any number of exact copies of them at will. If practical matter transmutation is also available (see Chapter 19), bags of sand could be dumped in at one end and Univacs and Mona Lisas would emerge from the other.

The second major class of matter transmission techniques is called the Transporter Beam. This system, familiar to viewers of the television series Star Trek, involves what computer specialists refer to as "destructive readout." The transmittee is somehow converted into patterned electromagnetic radiation which is fired across space, reassembling itself back to normal matter at a predetermined "focus." The original is destroyed during the conversion into photonic radiation. Only a transmitter is required and the subject is self-assembling at the destination without the assistance of a receiver mechanism.

Such a procedure, while seemingly improbable, is not wholly inconceivable in terms of modern science. We know that electrons can be converted into patterns of gamma rays by the addition of positrons. Furthermore, optics theory tells us that unsynchronized light waves give rise to regions of destructive and constructive interference. If the phase and frequency of electromagnetic radiation could be forced to enter into constructive interference in a compact volume of space, pair production might be initiated along with other related processes giving rise to structured matter. Or, if the theory held by a few physicists that mass consists of "standing light waves" has any plausibility, then it might be possible to induce the spontaneous conversion of energy into matter at remote points. The real trick would be to retain the complex structure of the living organism throughout the process of beamdown, and to handle the nearly 10¹⁹ joules of interconversion energy without mishap.

A third major class of teleportation technology, known as Matter Transposition, involves the passage of physical objects from point A to point B without traversing the intervening space (and without being destroyed or merely duplicated). In this case it is the original who completes the journey, unharmed. Similar in concept to the idea of space warps discussed earlier, transposition depends on the proposition that space is not only curved, as predicted by General Relativity, but is also wrinkled and discontinuous.

To make a trip, some mechanical or electronic device is used to render two points in space — say, where the passenger is and where he wants to go — contiguous. The subject is then fixed in the new position, and space allowed to snap back to its original configuration. As Donald Wollheim describes the process:

Two segments of space may be separated by thousands of light-years traveling along the visible three-dimensional continuum of space, yet may be touching each other like two pages of a book. The Gate then is merely an extradimensional means of cutting across this touching point and thereby avoiding the problem of having to travel those thousands of light-years inch by inch.⁹⁸⁴

If it turns out to be theoretically possible to selectively bend space-time locally by artificial means, the technological problems will be immense. For one thing, the energy required to adequately bend space would probably be prohibitive over distances of more than a few kilometers. A stellar-sized black hole, the best space-warper known to human science, has a mass-energy on the order of 10⁴⁸ joules. This represents the entire power output of a mature Type III civilization for ten seconds, and yet the BH causes severe distortion of space-time over distances of less than 100 kilometers. Also, as Larry Niven has pointed out, the simultaneous operation of two or more Matter Transpositors in close proximity could prove embarrassing.²⁷⁴⁴ At best, space would be bent in some unanticipated way, causing transmittees to arrive at some arbitrary and unscheduled destination. At worst, passengers could wind up gravitationally collapsed.

Two other teleportation schemes also involve the idea of point-to-point transmission without crossing the intervening space. The first of these, and easiest to understand, is the Tunnel Transporter. This hypothetical device operates on the same principle of quantum mechanical tunneling discussed earlier in connection with tachyon starships. Explains Larry Niven:

Apparently physics students are now taught that a tunnel diode takes an electron here and puts it there without allowing it to occupy the intervening space. If you can do it with quantum physics, why not with larger masses? With people? The theory looks good, and it hasn’t been used much in science fiction.²⁷⁴⁴

The second teleportation scheme, called the Fourier Transporter, requires a bit more explanation.²⁷⁸⁰ In the early 19th century, a brilliant French mathematician and physicist by the name of Baron Jean Baptiste Fourier determined that almost any function of a real variable could be mathematically represented as a sum of sine waves, each of whose wavelengths are integral multiples of the variable. Any three-dimensional function can be transformed mathematically into "Fourier space," a coordinate system which uses inverse wavelength for the axes rather than spatial position.

An object sitting in space near Sol has a representation in Fourier space (say, S) that is distinctly different from the representation of that same object in orbit around the star Arcturus (say, X). Terrestrial electronics engineers already know how to build digital "filters" that will accept any input S and output any response X in one dimension. The Fourier Transporter works as follows.

A device near Sol transforms a passenger, by means unspecified, into Fourier space as S. A universal filter, driven by a computer which calculates what X must be in accordance with the traveler’s itinerary, almost instantly converts S into X. The device then performs a reverse Fourier transform on X-and the passenger is gone! He emerges from Fourier space to find himself in orbit around Arcturus.

The validity of Fourier transforms out to mathematical infinity is crucial to the successful operation of the Transporter. If, as some have suggested, Relativity only limits the velocity of transfer of mass-energy and not information, then it might be possible to transmit information very quickly without using any form of mass-energy to do it.²⁰¹⁴ The Fourier Transporter would thus provide virtually instantaneous travel, at little or no cost in energy.

* Some of the natural philosophy and pragmatic aspects of matter transmission may be found in Cleaver,¹¹⁶⁷ Elliott,¹¹⁶² Gooden,¹¹⁶⁵ Lawden,^1170,1164 and Niven.²⁸⁰² [Ed. Note: And the Saga of the Cuckoo.]

** There is an interesting side issue respecting the accuracy of transmission. It is well-known among radiation scientists that the random alteration of one out of every 10⁸ atoms in the human body will produce death. That is, if more than one atom in every 100,000,000 transmitted by the Booth is erroneous, the passenger will get sick and probably die of symptoms resembling acute radiation poisoning.³⁸⁰ A Teleportation Booth with an error rate of 10⁹ bits/error would allow people to make only ten successive trips through the machine before death ensued.

Citing the tremendous difficulties involved in high speed interstellar journeying, many writers have turned in desperation to the concept of the "generation ship" or "interstellar ark."*

• These mammoth vessels would contain self-sufficient communities of the sentient spacefaring species and their offspring.²⁷⁵⁹
• Farfetched, sophisticated space drives would be unnecessary, since the revolving crew could tolerate trips lasting hundreds of years to the nearer stars.
• While the original explorer-colonists might never live to see the New World, their great-grandchildren and successive generations would survive to carry the great mission on to its conclusion.

Science fiction authors have described the social and genetic backsliding that could occur in such closed ecologies.²⁷⁹⁴

• The degree of discipline that each individual would have to accept would be more demanding than that of any present totalitarian regime here on Earth.
• Birthrates must be strictly controlled, psychological interactions skillfully managed, epidemiological and eugenics rules absolutely enforced.
• All aberrant ship-threatening behavior severely punished.
• From the human point of view the restrictions on personal freedom would be well-nigh intolerable.

Still, as Dyson points out, "we have no right to impose our tastes on others."²⁷⁹²

* See especially Bernal,²⁸²⁰ Clarke,²⁷⁸⁹ Gelula,²⁷⁹⁰ Haldeman,²⁸³⁹ Heinlein,²⁸⁵⁴ Macvey,⁷³² Panshin,²⁵⁷⁹ and Strong.⁵⁰

The generation ship would provide a pathway to the stars for any patient extraterrestrial species that either could not or would not build relativistic propulsion systems.

• Speeds from 1-5%c should be ample to commute between neighboring star groups in periods of only a few centuries.
• This can be done using relatively primitive space hardware.
• Our own Pioneer 10 probe, which departed the solar system a few years ago, is now heading out into the interstellar void at 0.004%c — a respectable velocity, considering that the craft was designed solely for interplanetary travel.

Of course, during the long journey the technology of the home planet will not stand still. In more than one science fiction story, the crew of the first interstellar ark arrives at their destination only to find that they had been passed many times en route by superior starcraft of more modern design, and that the target system had long since been colonized by others.²⁷⁹¹ James G. Strong suggests that "such action will only arouse bitterness among the pioneers, and it would be kinder to avoid their destination — certainly never to come within hailing distance of their ship."⁵⁰

Note that there is no absolute requirement that the full complement of consumables be carried on board the Ark at launch. According to C.A. Cross, "its materials balance could be sustained by the return to it of unmanned vehicles carrying raw materials on long stern chase trajectories."²⁷⁹³  Like the interstellar ramjet that picks up its fuel along the way, an "Ark runway" would enable a generation ship to pick up supplies positioned earlier across its flight path by unmanned cargo vessels dispatched from the home planet.

There are several other alternatives to the generation ship.
As Freeman Dyson once remarked:

"Interstellar travel is essentially not a problem in physics or engineering but a problem in biology."

• For instance, if medical science can learn how to prolong life indefinitely and create immortal astronauts, then the crew which began a lengthy voyage would live to see the end of it.
• The perspective of immortal beings would doubtless be quite farsighted, and it is not unreasonable to suppose that such creatures would have a leisurely, relaxed outlook on life.
• A century or two spent out of a 2000 year lifespan would seem no more painful than a 3-7 year voyage would to a human.
• Sea voyages of this length were common among sailors and traders of centuries past: Magellan’s global circumnavigation required 2 years, Sir Francis Drake’s 3 years, and Marco Polo’s excursion to China totaled 24 years.

Another possibility is the "sleeper ship," a well-worn science fiction theme during the last half-century.

• There are basically three classes of sleepers: Ectogenetic astronauts (discussed in the previous chapter), hibernauts, and cryonauts.
• Hibernauts are starship crew members whose metabolisms have been greatly slowed. Like bears, woodchucks, bats and many rodents, these interstellar travelers would "hibernate" for most of the trip.
• For starfaring hibernauts, objective centuries would melt into subjective hours, creating a delightful illusion of near-instantaneous travel.
• Experiments with small mammals here on Earth indicate that it may be possible to induce artificial hibernation in humans using a variety of specific metabolic inhibitors such as the antabolone found in aestivating lungfish.²⁷⁸⁵
• The addition of antabolone to other anti-metabolic ingredients should permit metabolism to be reduced to 1% of normal at temperatures near 0 °C.
• Hibernation for extended periods should be possible, although as in natural hibernation it will probably be necessary to periodically raise the temperature to normal for a few hours each month to allow certain cellular restorative functions to take place.⁶⁷

Cryonauts are interstellar travelers whose bodily functions have been entirely shut down. Placed in "suspended animation" at cryogenic temperatures, these starfaring passengers cross the Galaxy in compact, refrigerated vessels equipped with ultrareliable supercomputers designed to patiently wait out the lonely centuries and then automatically reanimate the frozen travelers when the target star system is reached. Robert Prehoda, a science writer and technology forecaster, speculates that:

Cryonauts may travel for many centuries between the stars in fully automatic self-repairing spacecraft controlled by immortal super-computers — descendants of "HAL" in 2001, A Space Odyssey. When they are revived, the journey will seem to have been only one night long. perhaps they will stay alert for a few years to explore new planets and transmit information about them back to Earth. Then they could be frozen again for another mission to a more distant star, repeating the freeze-revive-freeze cycle several times before circling back to Earth after an odyssey of many millenia.⁶⁷

Suspended animation will require only a modest-level biotechnology, in all probability.

• The main problem with freezing organic tissues is the extracellular formation of ice crystals which cause tissue damage, making reanimation impossible.
• Nevertheless almost every kind of mammalian tissue has already successfully been frozen and thawed under appropriate conditions.³⁶⁹⁷
• For instance, rabbit skin has been frozen to -196 °C in liquid nitrogen for 7½ months and is still viable when thawed.²⁷⁸⁶
• Successful freezing and thawing of rat pancreas cells down to -196 °C has been shown.²⁷⁸⁸
• Rat heart tissue can be reanimated after indefinite storage in liquid nitrogen.¹⁶⁸⁷
• Low temperature preservation of human blood cells, sperm and ova is now routine.

Whole organs have also been reanimated, though this is more difficult

• Marshal Shlafer and Armand M. Karow, Jr. successfully restored isolated rat hearts cooled to -30 °C and perfused with a commonly-used biological antifreeze called "dimethylsulfoxide," or DMSO.^1685,1692
• Dr. Isamu Suda of Kobe University in Japan froze a whole cat brain to -20 °C for more than 6 months using a DMSO cryoprotectant perfusate. After thawing, the brain was shown to have nearly normal electroencephalic wave tracings.^3694,3695

What about whole-body freezing?

• Many experiments during the past few decades have demonstrated that laboratory rats can be cooled to -10 °C and later restored to life in apparently normal condition.
• However, the period of "cold sleep" must not exceed a few hours and no more than 50% of the body fluids may be solidified.²⁷⁸⁷
• Lower lifeforms are much easier to freeze.
• Nematode worms, for example, survive suspended animation at liquid nitrogen temperatures indefinitely when subjected to a specific DMSO perfusion treatment.¹⁶⁸⁹

What about whole humans?

• The well-known mammalian diving reflex, together with the body’s lowered oxygen needs at temperatures close to freezing, have permitted people to survive drownings in icy river waters during literally hours of submersion.
• Dr. Ivan W. Brown, Jr. of Duke University Medical Center has successfully revived a human child whose body-temperature was reduced to 5 °C.⁶⁷

Following the successful cryopreservation experiments on dog kidneys performed by Dr. M.D. Persidsky at the Institute of Medical Science in San Francisco and Ronald Dietzman of the University of Minnesota, Robert Prehoda has tentatively suggested a hypothetical medical procedure for placing human beings into a state of reversible suspended animation:

The body temperature is lowered to 0° C and a heavy water (D₂O) perfusate now circulates through the body. Soon most of the H₂O molecules have been replaced with D₂O. A 5%-by-volume addition of fluorinated DMSO is now added to the perfusate. This chemical will partially protect the cells during freezing, but its main function is to act as a biological carrier, insuring that the powerful metabolic inhibitors will reach adequate levels within all the cells. Salt-free albumin and ATP are added to the perfusate, allowing the level of dissolved salts within the cells to be reduced. The pressure is greatly increased, and large quantities of dissolved xenon gas begin to be circulated through the body. The fluid-filled cavities around the brain, spinal cord and in the eyes are properly protected by separate perfusion systems.

The heavy-water-based perfusate is replaced with a liquid fluorocarbon which can hold large quantities of dissolved xenon. The pressure is slowly raised as the temperature is reduced. At 5000 psi, an optimum quantity of xenon can be perfused through the body, thoroughly penetrating every cell. No more xenon is needed. The pressure is slowly increased to 30,062 psi. The perfusate pump is shut off. The body temperature is -24 °C. The pressure is then lowered to 5000 psi and rapid solidification begins to take place through the body. Cooling continues as the pressure is again increased to 30,062 psi, allowing the heat of fusion energy to be dissipated. The up-and-down pressure cycle is repeated four more times during continuous cooling, permitting the body to be uniformly frozen. Xenon hydrate protects every cell against freezing damage. The body temperature continues to be lowered at a controlled rate until it is only 4.2 degrees above absolute zero — the temperature of liquid helium.

You are now in a state of complete suspended animation.⁶⁷

These steps may be followed in reverse order to achieve reanimation.*

Cryonauts may not be immortal.

• Every minute 10⁶ atoms of radioactive K-40 and 2 × 10⁵ atoms of C-14 decay in a human body, spraying bones and organs with beta particles and other low-level radiation.
• Accumulation of trace amounts of radionuclides is virtually inevitable for any carbon-based lifeform, and these minute natural emissions may produce genetic mutations and other irreversible cellular damage over millennia of cold storage.
• Prehoda estimates that the natural decay of radioactive isotopes in body tissues will cause a lethal accumulation of radiation damage in human cryonauts in roughly 35,000 years.
• This difficulty can perhaps be avoided by raising potential astronauts from birth in a carefully controlled radiation-free environment.
• Food, water, and air must be purified and made free of the harmful isotopes.
• This accomplished, cryonauts should last for millions of years in suspended animation (assuming adequate shielding from the cosmic ray background) and would be prime candidates for long-term low-velocity galactic exploratory and colonization missions.

* Already about fifty people have been frozen, using somewhat more primitive perfusal techniques, by several Cryonics Societies around the country. These methods may not prove successful, but we won’t know for sure until reanimation is attempted on one of the many frozen patients, perhaps a century from today.

Table 18.2 The Electromagnetic Spectrum

Radiative weapons are comprised of the class of devices which achieve their deadly results by the use of projected radiation — acoustic radiation is usually excluded from this category. There are two varieties of radiative weaponry: electromagnetic (photonic) and particulate (atomic and nuclear particles). We‘ll look first at the electromagnetic ones (Table 18.2).

Static fields need be considered only briefly. There is little or no evidence that mere electrostatic or magnetostatic fields have any effect whatsoever on the human organism. No gross effects have been observed in tests of laboratory animals subjected to magnetic fields up to several kilo-gauss.⁵⁶⁸ Likewise, few significant effects are reported from exposures to time-invariant electric fields. Hence, we find that static fields won‘t be useful to aliens as weapons.

VLF (Very Low Frequency) radiation has long been considered virtually harmless. It is emitted, for example, by power lines and electrical appliances we use every day. How could VLF possibly be harmful?

There are several interesting effects produced by exposure to slowly oscillating magnetic fields, such as the magnetic phosphene.⁵⁶⁶ The French physicist d'Arsonval was the first to describe these colorless "shimmering luminosities" in the last century. Application of VLF frequencies of from 10-100 Hz to the head causes these flickering phosphenes to appear at the borders of the visual field.⁵⁶⁸ Could ETs make us think we see ghosts?

• Muscle contractions have also been induced in frog tissue by VLF radiation.
• Furthermore, a study conducted in the Soviet Union a few years ago concluded that exposures to 50-100 volts per centimeter have significant effects on humans. Subjects reported tremors in arms and legs, slowed heartbeat, fatigue and sleepiness,⁵⁷⁰ and even anemia.⁶⁷⁹
• Recent Navy research has demonstrated that an electrical field at 60 Hz can alter the concentration of fats in the human bloodstream.⁴⁶³
• And according to the late Dr. Norbert Weiner, a 10 Hz ambient electrical field causes "unpleasant sensations."⁵²⁶ The oscillating field coincides roughly with the brain’s alpha-rhythm frequency.
• A variation of this technique, using scalp electrodes, is used to put human subjects to sleep — the so-called "Russian sleep machine" or "electrosleep."

But these findings are hotly contested by Dr. Otto H. Schmitt, Chairman of the Biophysics Group at the University of Minnesota. He recently completed a two-year study to determine whether or not man can detect VLF magnetic fields. Schmitt found that not one of his 500 subjects could consistently tell when the field was on or off. "Humans are relatively immune even to strong magnetic fields," he writes, "so long as they are not shocked, burned, or grossly polarized by the fields."⁶²⁹ He points out, however, that persons with prosthetic or bionic equipment (such as a pace-maker implant for the heart) might be particularly susceptible even to relatively low intensity VLF fields.

Accordingly, we can only note that at present the data are inconclusive. If it turns out that VLF is harmful after all, it’s a fair bet the aliens will know about it too!

Of course, we have been discussing using VLF against humans directly. But aliens could build giant inductors and utilize the well-known principle of inductive heating on any metallic object, such as cars and spaceships.⁵⁴⁸ Inductors use frequencies from 10 Hz up to 1 MHz, the former allowing uniform volume heating and the latter causing mere skin heating. A one-megawatt inductor weapon should be capable of raising one ton of metal about two degrees Celsius every second.*

* Such a weapon would require only two hours to raise an Apollo command module to red heat. The craft would reach its melting point four hours after heating began, and would be reduced to a spherical molten mass about ten minutes later.

Radio wave, microwave and infrared effects are manifested primarily as simple radiative heating.

• The longer radio waves cause thermal agitation and rotation of molecules, resulting in a rise in temperature of the bulk material subjected to irradiation.
• Microwave and infrared, on the other hand, stimulate molecules in what are called vibrational modes.
• Both infrared and visible radiation act on the whole molecule, causing direct heating. But the ultimate result is essentially the same — increased temperature.
• As far as specific destructive power is concerned, suffice it to say that a narrow beam of such radiation could burn a hole through a human with only a few tens of kilojoules of energy.

Infrared and lower-energy forms of electromagnetic radiation are known collectively as nonionizing radiation.

• Such radiation doesn‘t really alter the electronic state of the molecules themselves, but merely shakes them up a bit.
• It has been shown that nonionizing radiation doesn‘t cause genetic damage.
• Fruit flies tested under kilowatt Hertzian radiation for 12 hours evidenced no mutational changes whatsoever.⁶⁸⁰

Visible and ultraviolet light are considered to be slightly more "penetrating" forms of radiation.

• These photons are absorbed by the orbital electrons of atoms, but the energy thus absorbed is sometimes insufficient to knock the electrons clear of the atom.
• The excited but unionized atom is still plenty reactive, bringing about the production of deadly photo-products such as hydrogen peroxide in surface cells.
• UV is selectively absorbed by nucleic acids and proteins, and the mutagenic effects of UV bring on skin cancer.
• Exposures to as little as 600 joules over a naked human body causes surface cells to perish, "not only due to the disruption of nucleic acid synthesis, but also due to damage to the fine structures and disturbance of metabolism."⁴⁴⁵

As we move to still higher energy radiation, we enter the realm of X-rays and gamma rays.

• The activities of such radiations are not confined merely to the surface, but are instead deeply penetrating. These are called ionizing radiations.
• Photons of large energy are absorbed by orbital electrons but, unlike visible or some UV radiation, these electrons are hurled from the atom, leaving behind a charged ion. Such ionized atoms are extremely reactive chemically.
• The biochemical effects appear only after a period of latency, usually a few days or weeks.
• Radiosensitivity is marked in cells with high metabolism and high reproductive rates.⁶⁰⁴
• Lethality doses for man run approximately one kilojoule for X-rays (1.5 × 10¹⁷ photons/m²)
• Lethal dose of three kilojoules for "soft" gamma radiation (2 × 10¹⁵ photons/m²).³⁷⁹

How can electromagnetics be applied to the science of weaponry? The earliest use was the invention of radar. It’s generally assumed that if an alien spacecraft were to approach Earth without warning, our Ballistic Missile Early Warning System (BMEWS/SAGE) could not fail to pick it up. This is a gross misconception. In addition to the fact that the SAGE computers are specifically programmed to ignore any nonballistic UFO-like targets, our radars are only effective out to a few hundred kilometers, at best. An object a few megameters away, even if in Earth-orbit, could easily evade detection indefinitely. Farther out than that, and our chances of detecting the intruder are virtually zero. As Robert Salkeld points out in War and Space, it took the better part of a month for Earth-based observatories to locate and detect laser echoes from the specially-designed Apollo 11 reflector left behind on the surface of the Moon. Salkeld laments: "The far greater difficulty of picking up a distant target whose location and even existence are uncertain, and which is designed to be non-reflective, should be obvious."⁵⁶¹ A surprise attack from space is therefore quite possible.

But certainly the most alarming photonic weapons technology is the military laser. A bewildering array of possibilities has suddenly become available. For instance, it’s well known that to gaze into a laser beam of even low intensity can cause permanent blindness. It has been suggested that "satellite blinders" could be placed in orbit by aliens. Anyone who glanced at the sky for more than a few moments would become permanently and irreparably blind. Arthur C. Clarke uses a variation of this idea in his short story "The Light of Darkness."⁶³⁷

Another unusual application is the laser listening device. Victor Marchetti and John D. Marks, in their collaboration The CIA and the Cult of Intelligence, relate that in the early 1960s the CIA developed an apparatus which fired a tiny pencil of laser light at a closed window. Vibrations of the air inside the room — due to people talking — set the window pane vibrating. This in turn caused minute fluctuations in the reflected laser beam which could be decoded and reassembled back into the original speech, at the receiver! Although the contrivance apparently had a few technical bugs, the idea of spying on a nearby alien spacecraft — in windless, airless space — is intriguing.

The Pentagon is now examining the possibility of placing a network of "defense" satellites in orbit, each armed with powerful lasers. These orbital robots would approach and destroy "alien" hardware, or disable missiles that flew within range. The Soviets are reportedly working on a satellite-killer of their own.

This brings us to the "big daddy" of laser weaponry, the so-called laser cannons. The big breakthrough in high-power laser technology occurred when it was discovered that fast-flowing reactive gases could be chemically combined rapidly, releasing huge quantities of laser energy. The Gas Dynamic Laser (GDL), one of the major contenders in the high-power sweepstakes, produces a concentrated beam of laser light when its reaction gases are combined and forced through tiny nozzles at supersonic speeds.

It’s believed that prototype laser cannons will be available in the 1978-1979 period, and that working field models may be coming into use in the early 1980's.⁴⁶¹ Already the U.S. Army has fielded an experimental laser tank, called the Mobile Test Unit (MTU). From early in 1975, the MTU has been tested at the Redstone Arsenal in Huntsville, Alabama. The driver rides in front, aiming the turret in the rear at the desired target. The Electric Discharge Laser (EDL) in the turret fires a multi-kilojoule pulse, powerful enough to burn holes in wood, metal, or human flesh. Says a researcher on the MTU development team: "It‘ll go right through you right now with no trouble."³⁹²

There is also under development, by TRW Systems in Redondo Beach, California, a semi-portable laser rifle.

• Designed to be carried and operated by three men, this high-energy chemical laser is aimed like a shotgun and fired.
• It is supposedly capable of burning a centimeter-wide hole in an unprotected human body at a range of up to eight kilometers.
• "Once you‘ve got him in your sights," says one TRW engineer, "you‘ve got him. There are no misses."³⁹⁴

• As for gross power and destructive capability, Avco has reported that its eight kilowatt continuous-operation laser cuts through Plexiglas at about 2.5 cm per second.⁵²⁷
• The twenty kilowatt laser at the Air Force Avionics Laboratory near Dayton, Ohio, is capable of burning three centimeter wide holes in firebrick at the rate of 10 cm per second.
• It’s also known that the Air Force has since constructed GDLs capable of several hundred thousand kilowatts of contiuous power, although the exact details remain classified.³⁹⁷
• Dr. J. Paul Robinson at Los Alarnos speaks matter-of-factly about orbiting megajoule lasers in the near future.⁴¹⁰
• It is a fact that the Pentagon spent nearly $200 million in Fiscal 1976 on laser weapons technology alone.

High frequency lasers haven‘t actually been constructed as yet, but it has been emphasized repeatedly that both X-ray lasers⁴⁹¹ and gamma ray lasers, called grasers,^{475, 506} are theoretically possible. Even though practical feasibility has not been demonstrated, many scientists are already predicting that when x-ray lasers are constructed, energy fluxes "greater than one kilojoule per square centimeter" will be available.⁵⁰⁷

Admittedly, laser "death rays" have their limitations.

• Since light travels in a straight line, beams cannot be aimed at anything below the horizon unless orbital mirrors are used.
• Furthermore, laser light is scattered or absorbed by clouds, mist, dust, fog, and smoke.
• If the target is shiny and reflective, most of the laser’s energy can be dissipated harmlessly.

And yet it’s still considered a very promising weapon.

• It fires high-energy "projectiles" that travel at the speed of light.
• Aiming is vastly improved.
• Were lasers to be used in space battles, where beams can travel thousands of kilometers uninterrupted to their targets, it would represent a formidable weapon indeed. Our extraterrestrial invaders will surely be aware of this.

Two other photonic weapons deserve at least a passing mention. The first of these is the idea of using focused solar radiation as an offensive weapon. This idea is really quite old. In fact, the great Greek mathematician Archimedes was the first — to the best of my knowledge — to have actually put the plan to practice. Between 215 and 212 B.C., the Roman navy beseiged the Hellenic port of Syracuse. Archimedes set fire to the fleet by using polished reflectors* to concentrate the Sun’s heat onto the attackers.

In 1969 Dr. Thomas O. Paine, a former administrator for NASA, suggested that it might be possible to place a giant solar reflecting mirror on the lunar surface. This mirror, he claimed, could be used to destroy any chosen city on Earth.⁷⁷ Arthur C. Clarke has hinted that such a weapon might be wielded from Earth-orbit. "It’s theoretically possible," he asserts, "to orbit giant mirrors in space, to hover over the Equator and to reflect sunlight to any spot on Earth. And as they need only be made of mylar film coated with a few atoms' thickness of aluminum, they would be extremely light even if they were miles on a side. It would be technically feasible to erect such mirrors using Saturn V launch vehicles …"⁸¹

The second photonic device is the practical invisibility cloak. It is often pointed out that an invisible man would also be quite blind.⁵³ I can see no easy way around this fundamental objection. However, what if aliens wished merely to render isolated structures invisible? One suggestion along these lines entails the erection of a hemispherical cap over the buildings. The outer surface of this cap would consist of a 3-D holographic "picture" of the virgin terrain prior to the construction of said building. In this case, the ETs wouldn‘t particularly care whether or not they could see out from their hideout, as they could place TV cameras outside the periphery of the cloak. Or, if it is possible to maintain a radial refractive index gradient around the buildings, a kind of spherical lens might be created. The resulting image of the refracted background should be at least as good as a fine mirage, and perhaps even better — using advanced alien technology.

And of course we can always resolve the optics problem by resorting to subjective invisibility. That is, the alien causes humans to simply ignore his presence, psychologically. For all practical purposes, the ET would have become "invisible."⁵⁵ An interesting variation on this theme may be found in Larry Niven’s science fiction novel A Gift From Earth (Matt Keller’s Plateau Eyes.²³¹

* coppered shields, about a hundred of them trained on each enemy vessel.

How does particulate radiation affect the human organism? One most unusual effect relates to visual sensations caused by the passage of fast-moving particles through the retina. It has been reported that about 10% of all relativistic nitrogen nuclei shot through a human eyeball are perceived as tiny streaks of light in the visual field.⁴⁷³ High energy muons and pions have been found to cause a similar phenomenon, appearing as a crescent-shaped flash as large as one-half the entire field of view.⁵²⁹

But by and large, the biological effects of particulate radiation are quite straightforward.

• Any particle bearing an electric charge (protons, electrons) and having a reasonably high kinetic energy will interact strongly with the orbital electrons in any physical medium it passes through.
• Charged particles lose energy to orbital electrons bit by bit as they pass, unlike photons which divest all their energy in a single blast.
• Neutral particles like the neutron cannot interact electromagnetically with matter, and zip right past the orbital electrons.
• All their energy is transferred in a single collision with an atomic nucleus — which absorbs them and recoils violently.

• We call high-energy charged particles directly ionizing radiation.
• Whereas photons of very high energy and neutrons of all energies are referred to as indirectly ionizing radiation.
• Slow moving charged particles and low-energy photons are known collectively as nonionizing radiation.

Which of the particles in the "nuclear particle zoo" are germane to our study? At last count, well over 200 different particles had been discovered. Let us briefly consider just a few of them.

• We've already mentioned the proton (positive charge) and the neutron (neutral) — the constituents of atomic nuclei — and electrons (negative charge).
• Each of these has its antiparticle. An antiparticle is the "opposite" of a particle, in the sense that when the two come together they are observed to undergo annihilation (mutual destruction) and release large quantities of energy.

• The anti-electron, the first antiparticle to be discovered, was given a special name — the positron.
• The positron-electron annihilation reaction is very specific; positrons would presumably be stable in a universe without electrons.⁶⁸¹
• The proton and neutron each have their anti counterparts.
• However, they are slightly less specific in their reactions. An antiproton will annihilate both a neutron and a proton; likewise, the antineutron annihilates both neutrons and protons.⁶⁸¹

• Pions are particles which come in three varieties — positive, neutral, and negatively charged.
• They are produced via proton-antiproton and neutron-antineutron reactions, and also in cases where protons or neutrons collide with nucleons in normal matter.
• But pions are unstable, decaying to muons and electrons in very brief times.
• Muons exist in positive and negative forms and are also unstable, decaying in about two microseconds to electrons and other particles.

Let us turn now to applications.

The most common form of electron transfer in our everyday lives is via electricity. Can this be used as a weapon? Dr. John Cover, a scientist in Newport Beach, has developed a device he calls a taser. The taser passes a jolt of electricity at 50,000 volts (but very low current) through the body, temporarily freezing the skeletal muscles with few lasting effects. This "stun gun" is being manufactured and marketed under the trade name Taser Public Defender by Advanced Chemical Technology, a Los Angeles firm.

But this device gets the energy to the human target by firing tiny darts attached to ten meter threadlike wires. Surely there must be a better way!

The alien attackers may be capable of actually throwing thunderbolts at us, those powerful instruments of Zeus' arbitrary whim.

• One of the larger artificial lightning machines was the one built for the 1939 World’s Fair in New York. Its output reportedly exceeded ten million volts at about 200 kilojoules per bolt. This is sufficient to jump more than ten meters through dry air.
• Voltages of more than twenty million volts are commercially available today.

Natural lightning is even more impressive.

• Discharges from so-called "positive giants" pass energies in excess of several billion joules, at hundreds of millions of volts electrical potential.
• The cores of such strokes momentarily reach temperatures of up to 30,000 °C, several times hotter than the solar photosphere.
• It's quite possible that hovering alien spacecraft could use a weapon of this kind to destroy houses, vehicles, or even crowds or single individuals.
• A tight beam of ionizing radiation might precede the bolt to the ground, ionizing an easy conduction path in air straight to the target.
• It would be difficult to operate a hand-held device of this kind, such as a lightning bolt rifle, as it would be virtually impossible for the attacker to avoid being shocked himself.

Of course, there are other forms of lightning. Of particular interest is the phenomenon known as ball lightning.

• After decades of controversy, it is now generally accepted that these fiery balls of electrical energy — kugelblitz — do exist.
• They are described as being anywhere from one centimeter to one meter in diameter, in colors ranging from white and blue to red and yellow.⁴⁵⁹
• The plasma globes can be spherical or elliptical in shape.⁴⁶⁶
• Lifetimes are typically about five seconds, but occasionally a kugeiblitz has been seen to remain intact for more than a minute.
• Their demise occurs in one of two ways — silently (fast or slow), or explosively with a loud pop — and they generally travel at about 4 meters per second, either vertically⁶¹¹ or horizontally.⁴⁵⁹

How much energy do they contain?

• One 20 centimeter kugeiblitz fell into a small barrel of water, causing it to boil for several minutes.⁵⁴⁹
• Another plasma ball was seen entering a heavy oak piling, which shattered violently moments later.
• The ball was estimated to contain an energy of 100 kilojoules.⁶¹⁰
• Energy densities have been variously estimated from 20 megajoules per cubic meter⁶¹¹ up to 100 megajoules per cubic meter.⁵⁰⁵
• One author has speculated that persons standing within a meter or two of a large lightning ball might well be exposed to radiation sufficient to cause radionecrosis, although the balls are rarely reported to emit heat.⁵⁰⁵

Since ball lightning requires no ionized path and appears to be self-sustaining, it should be possible for ETs to wield portable kugeiblitz projectors.

• A person directly hit with one of these plasma balls could suffer severe radiation burns, electrocution, and traumatic shock.
• There is a small problem with aiming accuracy, as the motions of the glowing balls are frequently erratic.
• However, there have been many reports of ball lightning actually "chasing" people, apparently attracted to a small accumulated net charge.⁴⁶⁶
• Aim may in fact be a nonproblem after all.

Electrons can be utilized more directly in space.

• A beam of electrons could be fired at the hull of an alien spacecraft, embedding negative charges throughout its bulk.
• The craft might then be grappled electrostatically — a tractor beam of sorts.
• Unfortunately, the forces generated are quite weak over normal operational distances, and the skin charge would be easy to neutralize by the aliens themselves.

More reasonable, perhaps, are the torch weapons. The muon torch is a prime example.

• Muons are very inert mesons, so inert that they comprise about 80% of the cosmic rays at sea level and have been detected in mines, hundreds of meters beneath solid rock.⁶⁸¹
• The depth of penetration depends almost solely upon the initial energy of the beam of particles — the higher the energy, the farther they go.
• But muons decay after 2.2 microseconds. We can arrange the beam energy so that, after the muons have traveled, say, one kilometer, the decay time has elapsed.
• One kilometer from the source, then, the particles in the beam will suddenly decay, releasing their energy with almost pinpoint accuracy.
• Range can be adjusted on the muon torch by merely adjusting the energy of the beam.

Table 18.3 Range of the Charged-Pion Torch in Vacuum

Charged pions can also provide us with a torch effect. However, since charged pions decay in only 0.03 microseconds, to get the same range pions must be accelerated to energies about ten thousand times higher than muons (Table 18.3). But the pion torch is superior for one simple reason.

• When the muon decays, most of the energy thus liberated is carried away by neutrinos and is effectively lost.
• But when the pion decays, its full rest mass energy of 139 MeV is delivered to the target.
• If the aliens have constructed a pion torch capable of delivering a pion current of one milliampere — not inconceivable using modern human technology — the weapon would have a power at the target of about 150 kilowatts.*

• The problem with charged particle torches in general is that there’s an obvious defense available.
• Electrostatic screens around an enemy ship in space would repell the pions as easily as electrons are deflected in a TV picture tube.
• Only if torch weapons aren’t expected would the torchers have a fighting chance for success.

• Neutral pions are available too, of course, and would be quite undeflectable by any electrical field.
• There would be no elegant defense against a neutral pion torch.
• There’s just one catch. The neutral pion decays in 10^-15 seconds.
• To achieve the same range as a charged pion torch, energies must be some seven orders of magnitude greater.
• Even at the terrific energy of 1000 TeV, at least three orders of magnitude above the capacity of the largest accelerator on Earth, the neutral pions would have a range in vacuum of only 2.2 meters.

* Note also that the pion decay cloud could be materialized inside the enemy ship, incinerating everything within but leaving the hull intact.

Figure 18.3 The Starship Enterprise fires its phasers

We have not yet exhausted the list of nonphotonic radiative weapons. It has long been believed by many nuclear physicists that whole atoms of antiparticles could be built up — into anti-atoms.

• An atom of antimatter would have a negatively charged nucleus surrounded by a cloud of positrons.
• Recent research has revealed the first synthesis of the anti-helium-3 nucleus,⁴⁸⁷ and the antideuteron (anti-deuterium nucleus) has been known for a decade.
• It is not inconceivable that ETs may be able to fashion macroscopic chunks of pure antimatter, stored temporarily in some kind of (perhaps) magnetic confinement vessel.

A mere 64 grams of antimatter, released on the surface of this planet, would provide an explosive yield of one megaton — the approximate energy requirement to utterly destroy a city of one million inhabitants.⁵⁷³

Other applications for antimatter may be imagined.

• A cloud of anti-plasma released at an enemy vessel in space could cause severe structural weakening of the hull, as in the original-series Star Trek adventure "Balance of Terror" and other science fiction tales.⁶⁰⁷
• Another possibility is the use of antiparticle beams to slice up chunks of ordinary matter.
• A beam of anti-protons, for instance, would cut right through a distant spacecraft.
• Not only would the ship be physically riven in two, but fierce radiation accompanying the annihilation reactions would undoubtedly prove quite deadly to the occupants.

Aliens would be smart enough not to choose antiprotons for this purpose, however, as these are susceptible to electrostatic defenses. ETs would use antineutrons instead. Or they may use other forms of beam weapons that we not yet imagined (Figure 18.3).

We regard the weather as a weapon. Anything one can use to get his way is a weapon and the weather is as good a one as any.

The science of weather modification and climate control is still in its infancy. It is therefore much more difficult to assess the possibilities than in earlier sections. "High technology" necessarily implies a more speculative effort — not to imply that weapons discussed below are any less dangerous or less real. If any of the techniques described below turn out to be unworkable for one reason or another, it’s probably unimportant. The ETs undoubtedly have far more effective ones at their disposal!

Dr. Pierre St. Amand, doing weather modification research for the U.S. Navy in the mid-1960s, said of his work: "We regard the weather as a weapon. Anything one can use to get his way is a weapon and the weather is as good a one as any."

• In 1974, the Pentagon conceded it had used weather warfare in Vietnam for more than seven years.
• In point of fact, the CIA allegedly began a rainmaking project over Saigon as early as 1963.⁴⁷¹
• This disclosure infuriated the Soviets, who promptly introduced a resolution in the United Nations calling for multilateral renouncement of all geophysical and meteorological warfare.⁴⁶²

Man has been tampering with the weather in earnest since Schaefer and Langmuir's historic snowfall-induction experiments in 1946. Unfortunately, there have been many failures and progress has been slow.

• Silver iodide and dry ice have been used to precipitate rain for decades, and recently another technique — liquid propane sprayed into supercooled fogs — has been added to the list.⁴⁶⁵
• Hail suppression research appears promising,⁴⁶⁴
• Snowfall-induction for watershed and recreational purposes has become a commercial enterprise.⁴⁷⁴
• We can disperse fogs, prevent frost, and the NOAA's Project Stormfury has had limited success in reducing the severity of tropical hurricanes.

But man’s best efforts to date still appear rather feeble.

Could aliens find ways to generate earthquakes at will?

• Small tremors have already been artificially created by pumping water into the ground under pressure. This lubricates the fault lines, allowing the crustal plates to slip.
• Another technique is to set off high explosives at a weak point along a fault, jarring it loose suddenly. If the blast site were judiciously selected by alien geophysicists, the resulting quake could be devastating.
• Finally, there is the suggestion that earthquakes might be triggered by high intensity infrasound. It is well known that microseisms occur regularly at frequencies around 0.1 Hz,⁶²⁸ and the possibility exists that sympathetic resonances of some kind could be set up.
• Such oscillations could perhaps be induced using sonic booms. Researchers have discovered that infrasonic energy can be transmitted from the air to the ground; they have detected "air-coupled seismic waves resulting from fighter planes — flying at high altitudes at Mach numbers greater than 1.2. Such waves have also been detected in the ground below the paths of jet airliners."⁶²⁸

The average house-rattling earthquake liberates a total energy equivalent to hundreds of gigatons (about 10²¹ joules).

• Hurricanes are of similar intensity.
• But these cannot simply be "triggered" as can quakes, so we‘re faced with a much larger problem in trying to generate one.
• Tornadoes, the smaller cousin of the tropical hurricane, may be slightly easier to manage. D. S. Halacy, Jr., in The Weather Changers, notes that "there is evidence that a strong air temperature inversion at about 2 kilometers altitude is likely to produce tornadoes."⁵⁴⁷

Assuming such conditions exist in rudimentary form, can a cyclonic disturbance be generated?