Uncertainty: Einstein, Heisenberg, Bohr, and the Struggle for the Soul of Science - Hardcover

Lindley, David

Hardcover

ISBN 10: 0385515065 ISBN 13: 9780385515061

Publisher: Doubleday, 2007

Synopsis

The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.
—Werner Heisenberg

That God would choose to play dice with the world is something I cannot believe.
—Albert Einstein

Nothing exists until it is measured.
—Neils Bohr
The remarkable story of a startling scientific idea that ignited a battle among the greatest minds of the twentieth century and profoundly influenced intellectual inquiry in fields ranging from physics to literary criticism, anthropology and journalism

In 1927, the young German physicist Werner Heisenberg challenged centuries of scientific understanding when he introduced what came to be known as “the uncertainty principle.” Building on his own radical innovations in quantum theory, Heisenberg proved that in many physical measurements, you can obtain one bit of information only at the price of losing another. Heisenberg’s principle implied that scientific quantities/concepts do not have absolute, independent meaning, but acquire meaning only in terms of the experiments used to measure them. This proposition, undermining the cherished belief that science could reveal the physical world with limitless detail and precision, placed Heisenberg in direct opposition to the revered Albert Einstein. The eminent scientist Niels Bohr, Heisenberg’s mentor and Einstein’s long-time friend, found himself caught between the two.
Uncertainty chronicles the birth and evolution of one of the most significant findings in the history of science, and portrays the clash of ideas and personalities it provoked. Einstein was emotionally as well as intellectually determined to prove the uncertainty principle false. Heisenberg represented a new generation of physicists who believed that quantum theory overthrew the old certainties; confident of his reasoning, Heisenberg dismissed Einstein’s objections. Bohr understood that Heisenberg was correct, but he also recognized the vital necessity of gaining Einstein’s support as the world faced the shocking implications of Heisenberg’s principle.

About this title

About the Author:

david lindley holds a Ph.D. in astrophysics and has been an editor at Nature, Science, and Science News. He is the author of The End of Physics, Degrees Kelvin, Where Does the Weirdness Go?, and Boltzmann’s Atom. He lives in Alexandria, Virginia.

Excerpt. © Reprinted by permission. All rights reserved.:

Chapter 1
IRRITABLE PARTICLES
Robert Brown, son of a Scottish clergyman, was the archetypal self–made scholar, sober, diligent, and careful to the point of fanaticism. Born in 1773, he trained in medicine at Edinburgh, then served for some years as a surgeon’s assistant in a Fifeshire regiment. There he put his spare time to worthy use. Rising early, he taught himself German (nouns and their declensions before breakfast, his diary records, conjugation of auxiliary verbs afterward) so that he could master the considerable German literature on botany, his chosen subject. On a visit to London in 1798, the young Scotsman met and so impressed the great botanist Sir Joseph Banks, president of the Royal Society, that on Banks’s recommendation he sailed three years later on a long voyage to Australia, returning in 1805 with close to four thousand exotic plant specimens neatly stowed on his ship. These he spent the next several years assiduously describing, classifying, and cataloging, serving meanwhile as Banks’s librarian and personal assistant. Brown’s remarkable Australian trove, along with Banks’s own equally notable collection, became the heart of the botanical department of the British Museum, of which Brown became the first professional curator. He was, said a visitor to Banks’s London house, “a walking catalogue of every book in the world.”

Charles Darwin, before he was married, passed many a Sunday with the learned Robert Brown. In his autobiography Darwin describes a contradictory man, vastly knowledgeable but powerfully inclined to pedantry, generous in some ways, crabbed and suspicious in others. “He seemed to me to be chiefly remarkable for the minuteness of his observations and their perfect accuracy. He never propounded to me any large scientific views in biology,” Darwin writes. “He poured out his knowledge to me in the most unreserved manner, yet was strangely jealous on some points.” Brown was notorious, Darwin adds, for refusing to lend out specimens from his vast collection, even specimens that no one else possessed and which he knew he would never make any use of himself.

It is ironic, then, that this dry, cautious man should be commemorated now mainly as the observer of a curious phenomenon, Brownian motion, that represented the capricious intrusion of randomness and unpredictability into the elegant mansion of Victorian science. It was indeed the very scrupulousness of Brown’s observations that made the implications of Brownian motion so grave.

In June 1827, Brown began a study of pollen grains from Clarkia pulchella, a wildflower, popular today with gardeners, that had been discovered in Idaho in 1806 by Meriwether Lewis but named by him for his co–explorer William Clark. Characteristically, he intended to scrutinize minutely the shape and size of pollen particles, hoping that this would shed light on their function and on the way they interacted with other parts of the plant to fulfill their reproductive role.

Brown had acquired a microscope of recent and improved design. Its compound lenses largely banished the rainbow–hued fringes of color that afflicted the borders of objects seen in more primitive instruments. Under Brown’s eye the ghostly shapes of the pollen grains sprang clearly into view, their edges neatly delineated. Even so, the images were not perfect. The pollen grains wouldn’t stay still. They moved about, jiggled endlessly this way and that; they shimmered and stuttered; they drifted with strange erratic grace across the microscope’s field of view.

This incessant motion complicated Brown’s planned investigations, but it was not so very surprising. More than a century and a half earlier Antony van Leeuwenhoek, a draper from Delft, Holland, had astonished and delighted the scientific world when he described tiny “animalcules” of strange and myriad form that his crude microscope revealed in droplets of pond water, in scrapings from the unbrushed teeth of old men, and even in a suspension of ordinary household pepper crushed into plain water. “The motion of most of these animalcules in the water was so swift, and so various, upwards, downwards, and round about, that ’twas wonderful to see,” the entranced Leeuwenhoek wrote. His discovery not only spurred further scientific investigation but also led well–to–do citizens to purchase microscopes for their parlors and drawing rooms, where they could amaze their guests with this new wonder of nature.

Some animalcules had tiny hairs or finny extensions that enabled them to swim about. Others wriggled like little eels. It was easy to imagine that their meanderings were purposeful in some rudimentary way. Pollen grains, on the other hand, were simple in shape and had no moving parts. Still, they were undeniably organic. It seemed to Brown not unreasonable to suppose that pollen grains—especially as they were the male parts of a plant’s reproductive equipment—might possess some vital spirit that impelled them to move in their amusing but inscrutable fashion.

But Brown distrusted vague hypotheses of this sort. Observation, not speculation, was his forte. Testing pollen from other plants, he found that those grains danced about too. But then he examined minute fragments of leaves and stems and saw that those also jogged perplexingly about under his microscope’s gaze.

His attention caught by this “very unexpected fact of seeming vitality,” Brown could not help but probe the matter further. He obtained dust from dried plant samples, some more than a century old. He scraped tiny fragments from a piece of petrified wood. All these tiny grains had once been living but were now long dead, any vital spark extinguished. Examined under a microscope, they also shimmied. He moved on to truly inorganic material, knocking tiny shards from a variety of rocks and a piece of ordinary window glass. They too jiggled about. To put the case to the ultimate test, he scratched powder from a piece of the Sphinx, to which, as a curator of the British Museum, he had easy access and which he presumably regarded as certifiably, unarguably dead, on account of its provenance.

Placed in a drop of water under his microscope lens, ancient dust from the Sphinx danced about like everything else.

Brown acknowledged that he was not the first to see things jiggling about under the microscope. A certain Mr. Bywater of Liverpool, he noted, had a few years earlier looked at fragments of both organic and inorganic materials and observed “the animated and irritable particles” that they all shed. But Brown, through a variety of ingenious and careful experiments, established that the ceaseless motion of all these tiny fragments was neither the “animalcular motion” Leeuwenhoek and others had seen nor movement produced by vibration or turbulence of the fluid suspensions, by the action of heat, or through electric or magnetic influences.

This was contradictory and baffling. Dead particles of dust clearly couldn’t move of their own volition, nor was any external influence pushing them around. Yet move they all too plainly did. Brown himself made no attempt at an explanation. He was a careful descriptive botanist, not a philosopher of nature, and as Charles Darwin said, “much died with him, owing to his excessive fear of never making a mistake.”

Faced with this impossible dilemma, science took the prudent course and ignored Brownian motion for decades. Its deep significance went unnoticed because the phenomenon was so far beyond scientific apprehension. There was no way even to begin to grasp what it meant. Anyone who used a microscope knew about Brownian motion, at least as a great nuisance, but few read carefully what Brown himself had said about it. Most botanists and zoologists persisted in the idea that it was a manifestation of vital spirits, conveniently ignoring Brown’s demonstration that inert particles jiggled about just as much. Or else they decided their specimens were buffeted by heat or vibrations or electrical disturbances, ignoring Brown's experiments that ruled out those and other influences.

It was not until after Brown's death in 1858 that a few scientists began to see their way to an understanding of the phenomenon. As often happens in science, the observations could not be understood until there was at least the glimmering of a theory by which to understand them. The theory in this case was not a new idea but a very old one that science finally had the means to make sense of.

The Greek thinker Democritus, who flourished around 400 B.C, believed that all matter was made of tiny, fundamental particles called atoms (from the Greek atomos, indivisible). No matter how prescient this notion seems in retrospect, it was really a philosophical conceit more than a scientific hypothesis. What atoms were, what they looked like, how they behaved, how they interacted—such things could only be guessed at. Modern interest in atoms revived first among the chemists. In 1803, John Dalton in England proposed that rules of proportion in chemical reactions—hydrogen and oxygen combining in a fixed ratio to produce water, for example—came about because atoms of chemical substances joined together according to simple numerical rules.

Atoms didn’t gain credibility overnight. As late as 1860 an international conference convened in Karlsruhe, Germany, to debate the atomic hypothesis. The weight of opinion by now favored atoms, but there was significant dissent. Many distinguished chemists were happy to take laws of chemical combination as basic rules in their own right, and saw no reason to indulge in extravagant speculation about invisible particles.

August Kekulé, the German chemist who famously devised the ring structure of the benzene molecule while dozing in his fireside armchair and dreaming about snakes ca...

About this edition

• Publisher: Doubleday
• Publication date: 2007
• ISBN 10: 0385515065
• ISBN 13: 9780385515061
• Binding: Hardcover
• Edition number: 1
• Number of pages: 272