Gold designed his experiment to prove the experts wrong. The experiment was simple, elegant, and original. During World War II he had been working for the Royal Navy on radio communications and radar. He built his apparatus out of war-surplus navy electronics and headphones. He fed into the headphones a signal consisting of short pulses of a pure tone, separated by intervals of silence. The silent intervals were at least ten times as long as the period of the pure tone. The pulses were all the same shape, but they had phases which could be reversed independently. To reverse the phase of a pulse means to reverse the movement of the speaker in the headphone. The speaker in a reversed pulse is pushing the air outward when the speaker in an unreversed pulse is pulling the air inward. Sometimes Gold gave all the pulses the same phase, and sometimes he alternated the phases so that the even pulses had one phase and the odd pulses had the opposite phase. All I had to do was to sit with the headphones on my ears and listen while Gold put in signals with either constant or alternating phases. I had to tell him from the sound whether the phase was constant or alternating.
When the silent interval between pulses was ten times the period of the pure tone, it was easy to tell the difference. I heard a noise like a mosquito, a hum and a buzz sounding together, and the quality of the hum changed noticeably when the phases were changed from constant to alternating. We repeated the trials with longer silent intervals. I could still detect the difference, when the silent interval was as long as thirty periods. I was not the only guinea pig. Several other friends of Gold listened to the signals and found similar results. The experiment showed that the human ear can remember the phase of a signal, after the signal stops, for thirty times the period of the signal. To be able to remember the phase, the ear must contain fine-tuned resonators that continue to vibrate during the intervals of silence. The result of the experiment proved that pitch discrimination is mainly done in the ear and not in the brain.
Besides having experimental proof that the ear can resonate, Gold also had a theory to explain how a fine-tuned resonator can be built out of flabby and dissipative materials. His theory was that the inner ear contains an electrical feedback system. The mechanical resonators are coupled to electrically powered sensors and drivers, so that the combined electromechanical system works like a finely tuned amplifier. The positive feedback provided by the electrical components counteracts the damping produced by the flabbiness of the mechanical components. Gold’s experience as an electrical engineer made this theory seem plausible to him, although he could not identify the anatomical structures in the ear that functioned as sensors and drivers. In 1948 he published two papers, one reporting the results of the experiment and the other describing the theory.
Having myself participated in the experiment and listened to Gold explaining the theory, I never had any doubt that he was right. The professional auditory physiologists were equally sure that he was wrong. They found the theory implausible and the experiment unconvincing. They regarded Gold as an ignorant outsider intruding into a field where he had no training and no credentials. So for thirty years his work on hearing was ignored, and he moved on to other things.
Thirty years later, a new generation of auditory physiologists began to explore the ear with far more sophisticated tools. They discovered that everything that Gold had said in 1948 was true. The electrical sensors and drivers in the inner ear are now identified. They are two different kinds of hair cells, and they function in the way Gold said they should. The community of physiologists finally recognized the importance of his work, forty years after it was published.
Gold’s study of the mechanism of hearing is typical of the way he has worked throughout his life. About once every five years, he invades a new field of research and proposes an outrageous theory that arouses intense opposition from the professional experts in the field. He then works very hard to prove the experts wrong. He does not always succeed. Sometimes it turns out that the experts are right and he is wrong. He is not afraid of being wrong. He was famously wrong at least twice, once when he promoted the theory of a steady-state universe in which matter is continuously created to keep the density constant as the universe expands, and once when he predicted that the moon would be covered with electrostatically supported dust into which the astronauts would sink as soon as they stepped onto the surface. When he is proved wrong, he concedes defeat with good humor. Science is no fun, he says, if you are never wrong. His wrong ideas are insignificant compared with his far more important right ideas. One of his important right ideas was the theory that pulsars, the regularly pulsing celestial radio sources discovered by radio astronomers in 1967, are rotating neutron stars. Unlike most of his right ideas, his theory of pulsars was accepted almost immediately by the experts.
Another of Gold’s right ideas was rejected by the experts for an even longer time than his theory of hearing. This was his theory of the ninety-degree flip of the axis of rotation of the earth. In 1955 he published a revolutionary paper with the title “Instability of the Earth’s Axis of Rotation.” He proposed that the earth’s axis might occasionally flip over through an angle of ninety degrees within a time of the order of a million years, so that the old north and south poles would move to the equator, and two points of the old equator would move to the poles. The flip would be triggered by movements of mass that would cause the old rotation axis to become unstable and the new rotation axis to become stable. For example, a large accumulation of ice at the old north and south poles might cause such an exchange of stability. Gold’s paper was ignored by the experts for forty years. The experts at that time were focusing their attention narrowly on the phenomena of continental drift and the theory of plate tectonics. Gold’s theory had nothing to do with continental drift or with plate tectonics, and it was therefore of no interest to them. The flip predicted by Gold would occur much more rapidly than continental drift, and would not change the positions of continents relative to one another. The flip would only change the positions of continents relative to the rotation axis.
In 1997 Joseph Kirschvink, an expert on rock magnetism at the California Institute of Technology, published a paper presenting evidence that a ninety-degree flip of the rotation axis actually occurred during a geologically short time in the Early Cambrian Era. This discovery is of great importance for the history of life, since the time of the flip appears to coincide with the time of the “Cambrian Explosion,” the brief period when all the major varieties of higher organisms suddenly appear in the fossil record. It is possible that the flip of the rotation axis caused profound environmental changes in the oceans and triggered the rapid evolution of new life-forms. Kirschvink gives Gold credit for suggesting the theory that makes sense of his observations. If the theory had not been ignored for forty years, the evidence that confirms it might have been collected sooner.
Gold’s most controversial idea is the nonbiological origin of natural gas and oil. He advocates a theory that natural gas and oil come from reservoirs deep in the earth and are relics of the material out of which the earth condensed. The biological molecules found in oil show that the oil is contaminated by living creatures, not that the oil was produced by living creatures. This theory, like his theories of hearing and of polar flip, contradicts the entrenched dogma of the experts. Once again, Gold is regarded as an intruder ignorant of the field that he is invading. In fact, Gold is an intruder but he is not ignorant. He knows the details of the geology and chemistry of natural gas and oil. His arguments supporting his theory are based on a wealth of factual information. Perhaps it will once again take us forty years to decide whether the theory is right. Whether the theory of nonbiological origin is ultimately found to be right or wrong, the collection of evidence to test it will add greatly to our knowledge of the earth and its history.
Finally, the most recent of Gold’s revolutionary proposals is the subject of his book The Deep Hot Biosphere.1 His theory says that the entire crust of the earth, down to a depth of several miles, is populated with living cr
eatures. The creatures that we see living on the surface are only a small part of the biosphere. The greater and more ancient part of the biosphere is deep and hot. The theory is supported by a considerable mass of evidence. I do not need to summarize the evidence here, because it is clearly presented in the book. I prefer to let Gold speak for himself. The purpose of my foreword is only to explain how the theory of the deep hot biosphere fits into the general pattern of Gold’s life and work. Gold’s theories are always original, always important, usually controversial, and usually right. It is my belief, based on fifty years of observation of Gold as a friend and colleague, that the deep hot biosphere is all of the above: original, important, controversial, and right.
Postscript, 2006
Thomas Gold died in June 2004. Shortly before he died, an experiment was done at the Carnegie Institution of Washington Geophysical Laboratory to test his theory that natural gas is generated deep in the earth’s mantle.2 The experiment, carried out with tiny quantities of mantle materials exposed to high temperature and pressure in a diamond anvil cell, demonstrated abundant production of methane. The authors sent a message to Gold to tell him that his theory had been confirmed, only to learn that he had died three days earlier.
1. Springer-Verlag, 1999.
2. H. P. Scott et al., “Generation of Methane in the Earth’s Mantle: In Situ High Pressure–Temperature Measurements of Carbonate Reduction,” Proceedings of the National Academy of Sciences, Vol. 101, No. 39 (September 28, 2004), pp. 14023–14026.
4
THE FUTURE NEEDS US
PREY1 IS A thriller, well constructed and fun to read, like Michael Crichton’s other books. The main characters are the narrator, Jack, and his wife, Julia, parents of three lively children, successfully combining the joys of parenthood with the pursuit of brilliant careers in the high-tech world of Silicon Valley. Julia works for a company called Xymos that is developing nanorobots, tiny machines that can move around and function autonomously but are programmed to work together like an army of ants. Jack works for a company called MediaTronics that makes software to coordinate the actions of large groups of autonomous agents. His programs give intelligence and flexibility to her machines.
Things start to go wrong when Jack loses his job and is left to take care of the kids, while Julia is working longer and longer hours at her laboratory and losing interest in the family. She is engaged in a secret struggle to develop her nanorobots into a stealthy photo-reconnaissance system that can be sold to the United States Army. To increase the power and performance of the system, she incorporates living bacteria into the nanorobots so that they can reproduce and evolve rapidly. She reprograms them with Jack’s newest autonomous-agent software so that they can learn from experience.
Even with these improvements the nanorobots fail to meet the army’s specifications, and Xymos loses its army funding. After that, Julia desperately tries to convert the photo-reconnaissance system into a medical diagnostic system that can be sold on the civilian market. Her idea is to train the nanorobots to enter and explore the human body, so that they can locate tumors and other pathological conditions more precisely than can be done with X-rays and ultrasound working from the outside.
Experimenting with the medical applications of her nanorobots, she uses herself as a guinea pig and becomes chronically infected. The nanorobots learn how to establish themselves as symbionts within her body, and then gradually gain control over her mind. In her deranged state, she deliberately infects three of her colleagues at the laboratory with nanorobots. She also lets a swarm of nanorobots loose into the environment where they prey upon wildlife and rapidly increase in numbers.
The main part of the story concerns Jack’s slow realization that something is seriously amiss with his wife and with the project in which she is engaged. Only at the end does he understand the full horror of her transformation. With the help of a loyal young woman friend, he confronts Julia and douses her with a spray of bacteriophage that is lethal to the bacteria inside her. But Julia and her infected colleagues are no longer able to survive without the symbiotic nanorobots that have taken over their minds. Under the spray of bacteriophage they collapse and die, like the Wicked Witch of the West in The Wizard of Oz when Dorothy throws a bucket of water over her. After Julia’s demise, Jack and his girlfriend finish the job of destroying the nanorobots inside and outside the laboratory with fire and high explosives. In the final scene, Jack is back with his kids, wondering whether the nanorobots are gone for good, or whether the Xymos corporation may still be developing other nanorobot projects that will turn into nightmares.
What are we to make of this fairy story? There are two ways to look at it. On the one hand, we may enjoy it as a story and not worry whether some parts of it might come true. On the other hand, we may read it as an urgent warning of dangers lying ahead if present-day technological developments are allowed to continue. The author says plainly, in an introductory chapter with the title “Artificial Evolution in the Twenty-first Century,” that he intends his story to be taken seriously.
It is easy to demonstrate that the details of the story are technically flawed. Consider for example the size of the nanorobots. In a commercial presentation advertising the Xymos medical diagnostic system, Julia says, “We can do all this because the camera is smaller than a red blood cell.” The camera is one of her nanorobots. It must be as small as that, since Julia describes it swimming in the human bloodstream inside the capillaries that carry blood through the lungs. The capillaries are only just wide enough for red blood cells to pass through. But later in the book Jack encounters swarms of nanorobots chasing him in the open air like a swarm of ants or bees. These nanorobots are flying through the air as fast as he can run. Fortunately for Jack and unfortunately for the story, the laws of physics do not allow very small creatures to fly fast. The viscous drag of air or water becomes stronger as the creature becomes smaller. Flying through air, for a nanorobot the size of a red blood cell, would be like swimming through molasses for a human being. Roughly speaking, the top speed of a swimmer or flyer is proportional to its length. A generous upper limit to the speed of a nanorobot flying through air or swimming through water would be a tenth of an inch per second, barely fast enough to chase a snail. For nanorobots to behave like a swarm of insects, they would have to be as large as insects.
Other technical flaws in the story are easy to find. The swarms of nanorobots flying in the open air are said to be powered by solar energy. But the solar energy falling onto their very small area is insufficient to power their movements, even if we credit them with a magical ability to use solar energy with 100 percent efficiency. I could continue with a list of technical details that are scientifically impossible for one reason or another, but that would miss the main point of the story. The story is about human beings and not about nanorobots. The main point is that Julia is a credible human being. She is a capable and well-meaning woman in a responsible position, with the fate of a company resting on her shoulders. She decides that the only way to save the company from bankruptcy is to push ahead with a risky technology. Unable to face the failure of her company and her career, she continues with her experiments regardless of the risks. She is a gambler playing for such high stakes that she cannot afford to lose. In the end she loses not only her company and her career but her family and her life. It is a credible human story, and in the end the technical details do not matter.
This story reminds me of Nevil Shute’s On the Beach, published in 1957, a novel describing the extinction of mankind by radiological warfare. Shute’s poignant translation of apocalyptic disaster into the everyday voices of real people caught the imagination of the world. His book became an international best seller and was made into a successful film. The book and the film created an enduring myth, a myth which entered consciously or subconsciously into all subsequent thinking about nuclear war. The myth pictures nuclear war as silent inexorable death from which there is no escape, with radioactive cobalt sweeping sl
owly down the sky from the northern to the southern hemisphere. The people of Australia, after the northern hemisphere is dead, live out their lives quietly and bravely to the end. The Australian government provides a supply of euthanasia pills for citizens to use when the symptoms of radiation sickness become unpleasant. Parents are advised to give the pills to their children first before they become sick. There is no hope of survival; there is no talk of building an underground Noah’s Ark to keep earth’s creatures alive until the cobalt decays. Shute imagined the human species calmly acquiescing in its extinction.
The myth of On the Beach is technically flawed in many ways. Almost all the details are wrong: radioactive cobalt would not substantially increase the lethality of large hydrogen bombs; fallout would not descend uniformly over large areas but would fall sporadically in space and time; people could protect themselves from the radioactivity by sheltering under a few feet of dirt; and the war is supposed to have happened in 1961, too soon for even the most malevolent country to have acquired the megatonnage needed to give a lethal dose of radiation to the entire earth. Nevertheless, the myth did what Shute intended it to do. On the fundamental human level, in spite of the technical inaccuracies, it spoke truth. It told the world, in language that everyone could understand, that nuclear war means death. And the world listened.
Prey is not as good as On the Beach, but it is bringing us an equally important message. The message is that biotechnology in the twenty-first century is as dangerous as nuclear technology in the twentieth. The dangers do not lie in any particular gadgets such as nanorobots or autonomous agents. The dangers arise from knowledge, from our inexorably growing understanding of the basic processes of life. The message is that biological knowledge irresponsibly applied means death. And we may hope that the world will listen.
The Scientist as Rebel Page 5
