Borderlands of Science

by Charles Sheffield

  We reproduce the virus in large quantities, and release it in the city where El Supremo makes his home. People breathe it in, and it enters their bodies. If it begins to reproduce in any quantity, the T cells recognize its MHC coat as alien to the body (or rather, to that body's genetic code). They destroy the virus. The numbers of the virus remain in check. People breathe some out, which are in turn breathed in by other people.

  This goes on—until, weeks or months later, a sample of the virus is breathed in by El Supremo.

  At this point, everything changes. The virus is recognized by the T cells as part of El Supremo, because its protein coat looks like the right MHC molecules. The virus can continue the process of cell invasion and reproduction, and the T cells will leave it alone. A few days later, the tragic death of El Supremo is reported—struck down in his prime by a fatal viral infection.

  There is no suspicion of foul play. No one else becomes sick, or is in any danger. We employed a weapon that could harm no one in the world but El Supremo.

  Can we do all this, today? Not quite. But when the human genome mapping project is completed, a few years from now, we should have the genetic maps and the rapid DNA sequencers to do the job. War will become a more personal tool than it has ever been in the past.

  And war will take on a more generalized meaning. The use of the basic idea presented here is described in the novel Oaths and Miracles (Kress, 1996)—with organized crime controlling the biological weapon.

  12.4 Cyborgs. A cyborg is a rather ill-defined amalgamation of human and mechanical components. Most of us today are cyborgs. I am wearing glasses, and I have one gold tooth and another that has been capped with some unknown (to me) white material. I have friends with artificial hips and knees, a couple of others wear pacemakers. Most teenagers I meet have braces on their teeth.

  By science fiction standards this is pretty pathetic stuff. When we say "cyborg," we expect at the very least something like the Six Million Dollar Man, capable of feats of strength and speed beyond the human. If it is to be war—the enhanced warrior is a common feature of science fiction—then we demand the super-soldier, augmented and improved with built-in superhuman fighting equipment, like the speeded-up Gully Foyle in The Stars My Destination (Bester, 1956).

  Is such a creation possible?

  It may be, but it is not so clear that it is desirable. If you use a cyborg in a story you will find yourself constrained by the laws of both physics and biology. The human body, considered as raw material for war, has some severe drawbacks. If we have a choice of a human-machine combination, rather than pure human or pure machine, which human features would we keep?

  TABLE 12.1 (p. 300) offers a comparison of human and machine properties and limitations. We assume that there will be significant change in the next forty or fifty years in what computers and robots can do, but little change in human capabilities.

  We see that our big advantages lie in our versatility, built-in repair capability, and self-reproducing feature. Ideally, the cyborg will have the power to repair or reproduce itself. In the near future, the human part can do the repairs to the machine, but what about production of additional copies? A machine that repairs and reproduces itself from available raw materials is certainly a long-term possibility. But what then is the role of the human, as robotic reasoning powers increase?

  There is also the problem of mismatch, particularly on variables like physical strength. We can, if we choose, give our cyborg a "bionic arm," able to lift tons. But if the rest of the body is still flesh and bone, use of the bionic arm will produce intolerable stresses. The same problem will arise if we speed up the human reaction time too far. Our natural reaction speed is close to the limit of what our bodies can stand. The pulled muscles of Olympic sprinters attest to this.

  We may benefit by giving our cyborg enhanced sensory powers—it might be useful to communicate via bat-squeak signals, or see thermal infrared radiation—but we are unlikely to gain from superior strength unless it is accompanied by the installation of superhuman muscles and bones. One way to do this is via an exoskeleton to take the added stresses. However, if we are going outside the body with our improvements, we may as well go all the way and put ourselves inside a car or tank or spaceship. That has another great advantage. If the machine goes wrong, we can abandon it and get ourselves another one.

  My final conclusion: half a century from now, a cyborg will be regarded as an inferior form of robot. As a warrior, it will lose every fight to its totally inorganic foes.

  12.5 Cleaning up after nuclear war. Since 1945, the horrors of nuclear war have been graphically depicted in books and movies. After a while, recitation of biological and physical effects becomes numbing. It is hard for a rational mind to distinguish the effect of a 10-megaton TNT-equivalent hydrogen bomb from a 50-megaton TNT-equivalent bomb, because they are both so intolerable.

  Unfortunately, that does not mean they will never be used. Suppose that, despite all our efforts, a nuclear bomb (large or small) is exploded. One of the things that makes such weapons worse than their chemical equivalents is the longevity of their aftereffects. Some radioactive by-products have very long halflives. After the bombs have exploded, perhaps even after the causes of the war are forgotten, radioactive debris will remain.

  Must this be so? Must lands remain blighted for a hundred or a thousand years? Actually, all the evidence so far suggests no such thing. Life appears to be far too resourceful and adaptable to be discouraged by high ambient radioactivity. Plants and animals are thriving on the Pacific atolls where hydrogen bombs exploded forty years ago, and new growth appears in the very shadow of the Chernobyl reactor building. However, let us assume that radioactive waste is at least a nuisance. Can we see ways in which our descendants might cleanse radioactive ruins faster than Nature seems to permit?

  There is a way, at least in principle, with a "nuclear laser" that we don't yet know how to build.

  To understand how the device might work, consider the nature of radioactivity. The nucleus of a radioactive atom is unstable. It is, in energy terms, not in its ground state. After a shorter or longer time period, the nucleus will emit a particle which allows it to proceed to a state of lower energy. That state may actually be a different element. For example, if a nucleus emits an electron it will change to become the element next higher on the atomic table, since it now, in effect, has one more proton than before. If it emits an alpha particle (the nucleus of the helium atom) it will become the element two lower in the atomic table.

  The state of the nucleus after emission of a particle may be a "ground state," which means that the nucleus is now stable; or it may be a transitional state, in which case after a shorter or longer period another radioactive decay will take place, moving the nucleus to a lower energy level and again perhaps causing it to become a different element.

  The whole process of radioactive decay can be viewed as a nucleus moving to states of successively lower and lower energy, until it finally rests in the (stable) ground state. Although we know on average how long it takes a nucleus to go from one state to another—this is what the halflife measures, the time for half the nuclei in a large sample to make the change of state—there is no way to predict when any particular nucleus will undergo radioactive decay.

  As an example of the sequence of changes, consider plutonium. Element 94, it is not found naturally on Earth. It is presumably created, like other heavy elements, in supernova explosions, but it is radioactive and its most stable form, 94Pu244, has a halflife of less than a hundred million years. Here is the complete decay sequence, with the halflife indicated for each step, for a more short-lived form of plutonium:

  94Pu241 (13.2 years) to 95Am241 (458 years) to 93Np237 (2 million years) to 91Pa233 (27 days) to 92U233 (160,000 years) to 90Th229 (7,340 years) to 88Ra225 (14.8 days) to 89Ac225 (10 days) to 87Fr221 (4.8 minutes) to 85At217 (0.032 seconds) to 83Bi213 (47 minutes) to 84Po213 (4.2 microseconds) to 82Pb209 (3.3 hours) to 83Bi209.

  L
ook like gibberish? Sorry. Nuclear physicists and chemists deal with sequences like this every day.

  Bismuth, 83Bi209, is stable. The intermediate elements referred to in this radioactive decay chain are lead (symbol Pb, element 82), polonium (Po, element 84), astatine (At, element 85), francium (Fr, element 87), radium (Ra, element 88), actinium (Ac, element 89), thorium (Th, element 90), protoactinium (Pa, element 91), uranium (U, element 92), neptunium (Np, element 93), and americium (Am, element 95).

  What can we say about this rather messy chain of decay products? Well, almost all the time for the whole decay process comes with transitions that take 13.2 years, 458 years, 2 million years, 160,000 years, and 7,340 years. If we could somehow get rid of those, our dangerous plutonium 94Pu241 would turn to stable bismuth 83Bi209 in a few months.

  Is there any way to draw the fangs of radioactivity, by speeding up the long transitions?

  We return to the similarity between the atom and the nucleus, discussed in Chapter 5. There, we noted that the protons and neutrons of the nucleus, like the electrons of the atom, can be thought of as fitting into shells. There are excited states of the nucleus, as there are excited states of the atom, and for protons and neutrons such excited states of the nucleus are termed resonances. The whole phenomenon of radioactivity can be thought of as a nucleus, descending to its ground state by a series of transitions. "Forbidden" nuclear transitions are marked by very long decay times.

  What we need—but do not yet have, with the science of today—is a mechanism for stimulated nuclear emission. We need a nuclear laser, in which the application of radiation (very short wavelength) triggers a stimulated nuclear transition and accomplishes in minutes what normally takes thousands or millions of years. This would call for careful control, because all the energy provided by the transitions could be given off in a very short time. The process would have to be timed carefully, drawing off energy at a tolerable rate.

  However, there is another good side to this. We have found a potentially useful supply of free energy. In one possible future, maybe our despised dumps of radioactive wastes will be as sought after as today's oil fields.

  TABLE 12.1

  Comparison of human and machine

  performance and tolerances.

  Property

  Human

  Machine

  Gravity field/accn.

  0.25-2 gee*

  0-50,000 gee

  Hearing range

  20-20,000 cps

  0-106 cps

  Vision detail

  Resolves to one minute of arc

  Can easily resolve to one second of arc

  Vision wavelength

  red to violet range

  X-rays to long wave radio

  Air pressure

  0.3-1.5 atms.

  0-100,000 atms.

  Necessary support

  Air, food, water

  Power supply

  Operating rate

  Almost fixed

  Variable; includes zero rate (off)

  Speed of thought

  1,000 cycles/sec

  >1012 cycles/sec

  Mass

  15-500 kg**

  Any value

  Radiation tolerance

  Poor

  Easily hardened to radiation

  Mean time to failure

  < 100 years

  Variable; no reason why it should not be >1,000 years

  Strength

  Poor

  To limits of material science

  Versatility

  Excellent

  Very limited

  Repairs

  Automatic

  Needs external maintenance

  Production/ Reproduction

  Easy***

  Needs factory

  * A human can survive in free-fall, but physical deterioration,

  including bone loss, usually sets in after months in a low gravity field.

  ** There have been humans who weigh as little as 15 kg (33 pounds)

  and as much as 500 kg (1,100 pounds). I'm not sure either would be my choice for a warrior.

  *** Perhaps too easy.

  CHAPTER 13

  Beyond Science

  13.1 Scientific heresies. The intent of this book is to define the boundaries of science, in order that we can then consider going beyond them. This chapter, however, is a little different. Here we will consider "scientific heresies," ideas that are already beyond the boundaries of accepted science.

  I can make an argument that the place where any self-respecting scientist ought to work is in precisely the fringe areas where the uncertainty is greatest and our knowledge is least. Scientific heresies often appear when science has reached some kind of sticking point, but most scientists are reluctant to admit it. These are the areas in which the great leaps forward are likely to be made. In practice, most young scientists cannot afford to take the chance. The probability of failure is too great. Einstein said that the reason he could spend the last quarter-century of his life in a search (unsuccessful) for a unified field theory was that he could afford to; his reputation was already secure. A younger scientist takes a great risk by choosing to work in any field of scientific heresy.

  That does not mean the heretical ideas are necessarily wrong.

  I give the previous sentence special emphasis, because when I wrote on this subject a couple of years ago I received outraged letters defending people's favorite theories. How dare I say that such and such an idea was heresy?

  In each case, I had to write back and explain: A "scientific heresy" is a theory which runs contrary to the accepted scientific wisdom of a particular time. It is no more than that. It may eventually prove to be an improved description of Nature, so that it later (and often after much argument) becomes part of the standard world view; or it may prove to be misguided, and join the large group of discredited crank theories.

  Suppose a scientific idea is heresy. Is it wrong? I don't know. What I do know is that if most scientists, today, don't accept it, that is enough to make it a scientific heresy.

  As a first example, I offer something that fifteen years ago was certainly heresy. Now it seems on the way to becoming scientific dogma and uncritically accepted fact.

  13.2 Dinosaur doom. As proved by the huge success of Jurassic Park, people love dinosaurs. It is a long-lasting love affair. Fifty years ago, one of the most memorable segments of Walt Disney's movie Fantasia involved these animals. First we see dinosaurs feeding, raising their young, and hunting in a humid swamp world of frequent rains. Then we see a climate change, to a barren desert where the dust-clouded sun shines constantly. The water has all vanished, and nothing but dry bones and dead trees remain.

  This was an artistic portrayal of one of Nature's greatest mysteries: Why did the dinosaurs, the dominant land animal for one hundred and fifty million years, disappear? Moreover, why did they vanish so abruptly and so completely?

  Fantasia's answer, extreme climate change, introduced more questions than it answered. Clearly, our planet's lands did not all change to a dry and barren desert devoid of plants. Had that happened, the conquering of the land by plant forms would have had to start over from scratch, and there is no sign of such a thing in the fossil record. Moreover, since the dinosaurs were widespread, with their remains found everywhere from America to China, any climate change would have to be not only severe, but ubiquitous. More recent suggestions, that dinosaurs were warmblooded creatures, make their worldwide extinction by climate change even more unlikely. Finally, we have to ask why the disappearance of the dinosaurs happened so quickly.

  Even fifty years ago, when Fantasia was produced, it was possible to object to the picture painted in the Disney movie. On the other hand, no one had a better answer. Climate change, perhaps accompanying a period of high volcanic activity, seemed like the best available explanation for what is referred to in scientific circles as "the K/T extinction." The K/T boundary is the time when the geological time period known as the C
retaceous Period ended and the Tertiary Period began. Why K/T, rather than C/T? Because geologists refer to geological strata using a single letter, and C is already taken for the Carboniferous Period (which ended about 140 million years before the Cretaceous Period began). At the same time as the dinosaurs vanished from the Earth, so too did all the large flying reptiles and the largest marine reptiles. It is logical to assume that the cause of all three disappearances was the same, on land, air, and sea.

  A new possibility appeared in 1978, when a son brought home a rock sample and showed it to his father. The son was Walter Alvarez, a geologist and geophysicist and a professor at the University of California at Berkeley. The father was the late Luis Alvarez, a physicist who had won the 1968 Nobel Prize for his contributions to elementary particle physics. The rock had been dug by Walter Alvarez himself from a gorge in the Italian Apennines. Its lower part was white limestone, its middle a half-inch layer of hardened clay, its upper part red limestone. The boundaries between the three sections were quite clearly defined. Walter Alvarez knew that a similar clay layer was to be found all around the world. The clay had been laid down on the ocean floor sixty-five million years earlier—right about the time that paleontologists believed that the dinosaurs became extinct.

  Luis Alvarez thought it might be possible to determine how long the clay layer had taken to form by a technique involving induced radioactivity, and he and his son looked in the rock sample's clay layer for the presence of a suitable substance. Sure enough, they and their co-workers found iridium—but they discovered three hundred times as high a concentration of that element in the clay as in the limestone layers above and below it. Since iridium is rare in the Earth's crust and much more common in meteorites that fall to the Earth, it seemed possible that the clay layer might be tied in with some major extraterrestrial event.