Coming of Age in the Milky Way (36 page)

Darwin’s initial inclination was to take the high road, renouncing his priority and giving all the credit to Wallace. “I should rather burn my whole book, than that he or any other many should think that I had behaved in a paltry spirit,” he told Lyell.
²⁶
But Lyell and Hooker prevailed upon Darwin instead to publish a joint announcement of his and Wallace’s conclusions, and then to get to work writing a briefer account of his theory for prompt publication in book form. This he did, rushing to complete what he called an “abstract” of his theory within a year. This was
The Origin of Species by Means of Natural Selection
.

More than two hundred thousand words in length, the
Origin
reads less like an abstract than like a steady, not to say relentless, recounting of specifics: The incidence of beetle spoilage in American purple plums; the size of the stem of the Swedish turnip; the exact number of tail feathers sported by the trumpeter pigeon; the tactics employed by male alligators when they fight over female alligators. The book is objective to the point of bloodlessness; here are to be found no ecstatic outbursts comparable to Copernicus’s tributes to the sun, no philosophizing on a level with Newton’s descriptions of the workings of God, none of the fiery contentiousness of Galileo’s dialogues. Instead there is a constant amassing of factual detail, gradual as a silt deposit hardening into sedimentary rock.
^*

Indeed, the book was
so
detailed and modest that it struck many readers as self-evident. This was a source of strength, in that nothing so persuades a man to accept a novel idea as the sense that he already knew it to be true. (“How extremely stupid of me not to have thought of that,” said Thomas Huxley, previously an evolutionary skeptic, upon reading the
Origin.
²⁷
)
Many scientists and
scholars soon came around to Darwin’s point of view—Hooker at once, the botanist Asa Gray soon thereafter, and Lyell, remarkably for a public figure so prominently established as an antievolutionist, only five years later—though more than a few of them would have agreed with Whitehead, who in a conversation in 1944 declared that “Darwin is truly great, but he is the dullest great man I can think of.”
²⁹
Darwin replied to contemporary criticism in this vein with his customary restraint:

But he conceded that, though the study of living things had never lost its fascination for him, the years of drudgery had taken a toll on his nonscientific interests: Neither music nor literature nor even “fine scenery” held much pleasure for him any longer; he wrote in his
Autobiography:
“My mind seems to have become a kind of machine for grinding general laws out of large collections of facts.”
³¹

The religious reaction was every bit as vehement as Darwin had feared, but much of it was so florid, compared to Darwin’s quiet reasonableness, that it flowed around the
Origin
like water around a rock. Bishop Wilberforce of Oxford set the tone for the long burlesque that was to follow. A passionate lecturer, called “Soapy Sam” after his habit of rubbing his hands together as he preached, Wilberforce condemned Darwin’s theory as “a dishonoring view of Nature…. absolutely incompatible with the word of God.” A prisoner of his own passion, he soon overplayed his hand. The scene was a meeting of the British Association for the Advancement of Science, at Oxford on June 30, 1860. Taking part in the discussion was Thomas Huxley, who loved a good argument and styled himself “Darwin’s bulldog” for his tireless sallies against the opponents of evolution. With a sarcastic smile, Wilberforce turned to Huxley and asked “was it through his grandfather or his
grandmother
that he [Huxley] claimed his descent from a monkey?”
³²
“The Lord hath delivered him into mine hands,” whispered Huxley
to his friend Benjamin Brodie, seated beside him. Then he rose, savoring the moment, and replied:

The audience broke into laughter. In the general excitement that followed, one Lady Bruster fainted and had to be carried from the hall, while Captain Fitz-Roy of the
Beagle
marched up and down the aisles, holding a Bible aloft and chanting, “The Book, the Book!”
³⁴
The drama of Darwinism versus Christian fundamentalism went on to play to packed houses in the Dayton, Tennessee, courthouse where Clarence Darrow defended John Scopes, and road-show productions were still drawing crowds to the so-called “creation science” trials of the 1980s. One such case reached the Supreme Court of the United States, which voted in 1987 that the state of Louisiana did not have the right to require that creationism be taught alongside evolution in the public schools (Chief Justice William Rehnquist dissenting). But science is not rhetoric, and the evolutionary debates, though entertaining, were always more show than substance.

The ascent of Darwin’s theory brought new vitality to the question of the age of the earth. Darwinism was a
time
bomb: For species to have evolved to their present-day diversity through the slow workings of random mutation and natural selection required that the duration of the past be much longer than the six thousand or so years suggested by the Bible. Darwin grasped this nettle firmly: “He who … does not admit how vast have been the past periods of time may at once close this volume,” he wrote in the
Origin.
³⁵

But while Darwin’s evolution and Lyell’s geology implied that the earth was old, they did not prove it. That issue was left to the physicists, who approached the question of the age of the earth by
way of thermodynamics, the developing science of the transfer of heat. The earth, as coal miners know, is hotter in its depths than at the surface. Therefore it must be radiating heat into space, rather than receiving all its warmth from the sun. (Were it the other way around, the earth’s surface would be hotter than its interior.) If, then, one assumed that the earth began as a molten ball and has been cooling ever since, and if one could determine the rate at which it is cooling, it ought to be possible to calculate its age.

The first significant experiments along these lines had been conducted in the 1770s by Buffon, an early champion of deep time. In a thermally stable basement laboratory, Buffon fashioned little spheres one to five inches in diameter from suitably earthy materials, heated them, determined how long it took them to cool, and extrapolated the results to the much larger sphere of the earth. He made his measurements by sitting in the dark and observing how long it took a white-hot ball to fade to invisibility, or by touching them with his hand until they seemed to have returned to room temperature. The results, though admittedly crude, yielded a geochronology generous by the standards of the day: Buffon calculated that the earth was some 75,000 to 168,000 years old, and he guessed privately that the true figure was probably closer to half a million years. This, however, was still far too little time for Darwinian evolution to have brought life on Earth from a single-celled organism to the present-day world of orchids and adders and chimpanzees.
That
feat would have required
billions
of years.

Thermodynamics had advanced a long way by the time Darwin came on the scene. Thanks in large measure to its important practical applications in the design of steam engines, the study of heat attracted some of the most intrepid intellects of the nineteenth century—men of the stature of Lord Kelvin, Hermann von Helmholtz, Rudolf Clausius, and Ludwig Boltzmann. But when all this brainpower was brought to bear upon the question of geochronology, the verdict was bad news for Darwin and the uniformitarian geologists.

The titans of physics chose to focus less on the earth than on that suitably grander and more luminous body, the sun. Helmholtz was helpful: An able philosopher as well as a scientist, he was amused to read that the late Immanuel Kant (with whom he disagreed over just about everything) had thought that the sun was “a flaming body, and not a mass of molten and glowing matter.”
³⁶
This Helmholtz the physicist knew to be wrong; were the sun simply burning like a giant campfire, it would have run out of fuel in but a thousand years. Casting about for an alternative solar energy-source, Helmholtz hit upon gravitational contraction: The material of the sun, he reasoned, settles in toward the center, releasing gravitational potential energy in the form of heat. This, the most efficient solar energy-production mechanism that could be envisioned by nineteenth-century physics, yielded an age for the sun of some twenty to forty million years—a lot longer than the chronology of Buffon or the Bible, though still not enough to satisfy the Darwinians.

The question of the age of the sun then was taken up by Lord Kelvin, an imposing figure by any intellectual standard. Born in Belfast in 1824, Kelvin (né William Thompson) was admitted to the University of Glasgow at the age of ten, had published his first paper in mathematics before he was seventeen, and was named professor of natural philosophy at Glasgow at age twenty-two. An adept musician and an expert navigator as well as a distinguished mathematician and physicist and inventor, Kelvin was a hard man with whom to differ. Moreover, his forte was heat: The Kelvin scale of absolute temperature is named after him, and he was instrumental in identifying the first law of thermodynamics (that energy is conserved in all interactions, meaning that no machine can produce more energy than it consumes) and the second law (that some energy must always be lost in the process). When Kelvin declared the verdict of thermodynamics as to the question of the age of the sun, few mortals, and fewer biologists, could expect both to differ with him and to prevail.

Kelvin calculated that the sun, releasing heat by virtue of gravitational contraction, could not have been shining for more than five hundred million years. This was a disaster for Darwin. “I take the sun much to heart,” he wrote to Lyell in 1868. “I have not as yet been able to digest the fundamental notion of the shortened age of the sun and earth,” he wrote to Wallace three years later.
³⁷
Huxley the bulldog dutifully debated Kelvin on geochronology, at a meeting of the Geological Society of London, but Kelvin was no Bishop Wilberforce and Huxley got nowhere. Clearly either Darwin’s theory or Kelvin’s calculations were wrong. Darwin died not knowing which.

To their credit, both Darwin and Kelvin allowed that something
important might be missing from their considerations. As Darwin put it, pleading his case in a late edition of the
Origin
, “We are confessedly ignorant; nor do we know how ignorant we are.”
³⁸
Kelvin, for his part, admitted that his assessments of the age of the sun depended upon the accuracy of Helmholtz’s hypothesis that solar energy came from the alleged contraction of the sun. He remarked, in one of the most pregnant parenthetical phrases in the history of physics, that “(I do not say there may not be laws which we have not discovered.)”
³⁹

It was in conceding that their views might be incomplete that both men proved most prophetic. What they lacked was an understanding of two of the fundamental forces of nature, known corporately as nuclear energy. It is the decay of radioactive material —via the weak nuclear force—that has kept the earth warm for nearly five billion years. It is nuclear fusion—which also involves the strong force—that has powered the sun for as long, and that promises to keep it shining for another five billion years. With the discovery of nuclear energy the time-scale debate was resolved in Darwin’s favor, the doors to nuclear physics swung open, and the world lost its innocence.

The nuclear age may be said to have dawned on November 8, 1895, in a laboratory at the University of Würzburg, at the hands of the physicist Wilhelm Conrad Röntgen. Röntgen was experimenting with electricity in a semi vacuum tube. The laboratory was dark. He noticed that a screen across the room, coated with barium, platinum, and cyanide, glowed in the dark whenever he turned on the power to the tube, as if light from the tube were reaching the screen. But ordinary light could not be responsible: The tube was enclosed in black cardboard and no light could escape it. Puzzled, Röntgen placed his hand between the tube and the screen and was startled to see the bones in his hand exposed, as if the flesh had become translucent. Röntgen had detected “X rays”—high-energy photons generated by electron transitions at the inner shells of atoms.
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Among the scores of physicists who took notice of Röntgen’s detection of X rays was Henri Becquerel, a third-generation student of phosphorescence who shared with his father and grandfather a fascination with anything that glowed in the dark. Becquerel’s discovery, like Röntgen’s, was accidental, though both illustrated the validity of Louis Pasteur’s dictum that chance favors the prepared mind. Between experiments in his laboratory in Paris, Becquerel stored some photographic plates wrapped in black paper in a drawer. A piece of uranium happened to be sitting on top of them. When Becquerel developed the plates several days later, he found that they had been imprinted, in total darkness, with an image of the lump of uranium. He had detected radioactivity, the emission of subatomic particles by unstable atoms like those of uranium—which, Becquerel noted in announcing his results in 1896, was particularly radioactive. His work helped initiate a path of research that would lead, eventually, to Einstein’s realization that every atom is a bundle of energy.