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Product Details
| ISBN-13: | 9781616142810 |
|---|---|
| Publisher: | Rowman & Littlefield Publishers, Inc. |
| Publication date: | 09/27/2011 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 338 |
| Sales rank: | 562,280 |
| File size: | 4 MB |
About the Author
Christopher T. Hill, PhD is the coauthor with Leon M. Lederman of Quantum Physics for Poets and Symmetry and the Beautiful Universe. He is a theoretical physicist (Scientist III) and the former head of Theoretical Physics at Fermi National Accelerator Laboratory.
Read an Excerpt
Quantum Physics for Poets
By LEON M. LEDERMAN CHRISTOPHER T. HILL
Prometheus Books
Copyright © 2011 Leon M. Lederman and Chrisopher T. HillAll right reserved.
ISBN: 978-1-61614-233-9
Chapter One
If You're Not Shocked, You Haven't Understood
In the TV series Star Trek, and in its subsequent derivatives, the starship Enterprise travels throughout intergalactic space. Its five-year mission of exploration is to go where no human being has gone before. Using the imaginative technology of the distant future, the crew of the Enterprise travels at warp speeds, many times the speed of light, calls home to Star Fleet Command from a distance of many parsecs, using "subspace communication," and scans approaching vessels and the surfaces of new planets, occasionally defending itself against hostile forces with photon torpedoes. And, perhaps most innovative of all, the starship crew members can "beam" themselves to the surfaces of many new worlds to explore strange landscapes and have face-to-face meetings with the leaders of alien civilizations, which are sometimes more, sometimes less, advanced.
In not one of the many episodes of Star Trek, however, or to our knowledge any other science fiction saga, has there ever been as bizarre an exploration of the universe as that which actually took place on planet Earth in the period 1900 to 1930 CE. The distances traveled by the explorers of the early twentieth-century scientific age were similarly vast, but not in the sense of the large scales of billions and billions of light-years of intergalactic space. Rather, it was a voyage into the deep, the unknown, and the unexplored space of the smallest objects that make up the entire universe, down to the scale of billionths and billionths of an inch.
The advancing technology and scientific skills at the turn of the nineteenth to the twentieth century enabled these scientist explorers to, in a sense, visit for the first time the domain of a remarkable and new alien civilization, the world of the atom. What they encountered was incredible, existential, and surreal: it was as if the art, music, and literature of the age—the eyes of Picasso, the ears of Schoenberg, and the pen of Kafka—were in lockstep with the physicists unraveling a weird, bizarre, and unfamiliar new world within the innermost depths of nature. Virtually all of science's sophisticated and well-honed "classical" knowledge of the laws of physics, with its rules acquired and polished over the previous three hundred years, proved to be dead wrong in this strange new world. It was as if Captain Kirk and his Enterprise mates had landed on a planet in which the very laws of nature were as different as those encountered by Alice after she fell down the rabbit hole. It was a new kind of "dream logic" reality. Objects placed over here appeared over there, instantaneously. A smooth, hard stone began to blur and diffuse into seeming nothingness as scientists watched. Solid walls could be promenaded straight through, effortlessly. Things jumped wildly about in space and time.
Plenty of "particles" of matter existed in this strange new world, swarming around, to and fro. By carefully observing these particles the scientists learned that they did not simply pass uniformly from starting point A to arrive at a well-defined time at destination point B. Motion was nothing as Galileo or Newton had conceived it three hundred years earlier. Instead, the "fundamental particles" of nature, out of which everything is composed, such as the tiny electron, were seen to explore all possible paths in getting from A to B—all at once! Particles were always nowhere and yet everywhere at the same time. They arrived at their destinations with a spooky knowledge of every available path they could have, or might have, taken, with no certainty as to which path they actually did take. The scientists toyed with the particles, blocking off some of the available paths they might have taken from A to B, and they found that their arrival at B could be influenced in this way—merely changing one of the many available paths a particle may have taken, whether it did so or not, could cause it to arrive at B more often—or not at all.
Particles, little pinpoints of matter with no apparent or discernable internal clockwork or organs, leave sharp tracks in detectors and little dots of light on fluorescent screens and cause Geiger counters to go "click ... click ... click, click ... click." Yet, these minute dots of matter now also appear to be waves. They display wavelike, cloudlike, blurry patterns of motion, with crests and troughs like the waves on the surface of a lake or the sea. And things that were thought to be waves, like radio waves and light, were now found to be particles. Waves became particles and particles became waves. Neither, or, yet both, and all at once. It was as if the radical artists, composers, and writers of the age were scripting the laws of nature.
In short, the world dramatically changed before the eyes of the early twentieth-century explorers—eyes that now peered through highly sophisticated instruments. The universe was now seen to work in a way starkly different from what science had taught over the previous three centuries of enlightenment, beginning with the Renaissance. This grand change of our understanding of the physical world marked the arrival of an entirely different way to view nature and was now giving rise to the birth of a whole new and more fundamental science—quantum physics.
Physicists wrestling with the new experimental data and theoretical ideas about the atom strained to use human language and metaphors that had been invented in the traditional world of the old classical era of Galileo and Newton, but they found them hopelessly inadequate to describe their new experiences. The world now seemed to require descriptors such as fuzzy, uncertain, and spooky action-at-a-distance, as if ghosts were running around influencing the outcome of experiments.
There emerged a new concept called "wave particle duality" to reconcile why waves were sometimes particles and why particles were sometimes waves, though scientists were still bewildered. So bizarre are the consequences of quantum physics that, perhaps to preserve their sanity, the quantum physicist pioneers were driven to denial that they were actually describing a vast new reality, preferring to objectively insist that they had "merely" invented a new method for making predictions about the results of possible experiments—and nothing more.
AN ADVANCE PEEK AT QUANTUM PHYSICS
Prior to the quantum era, scientists had been definitive in their statements about cause and effect and precisely how objects move along well-defined paths, as they respond to various forces applied to them. But the classical science that had evolved from the mists of history, to the end of the nineteenth century, always involved descriptions of things that are collections of a huge number of atoms. For instance, some million-trillion atoms are contained in a single grain of sand.
Observers prior to the quantum age were like a distant alien civilization examining large collections of humans from afar, observing them only in crowds of thousands, tens of thousands, or more. They might have observed humans marching in parades, or breaking into applause, or scurrying to work, or about in every which way. Nothing would have prepared such remote alien observers for what they would find upon examining individual human behavior up close. New behaviors would then be encountered as humans displayed signs of humor, love, compassion, and creativity, traits that would be totally unexpected, given the experience of having only observed the behavior of human mobs from afar. The aliens, if they themselves were insects or automatons, may not even have a ready vocabulary to describe what they were now observing in up-close human behavior—indeed, even today the accumulated poetry and literature of the human race, for example, from Aeschylus to Thomas Pynchon, does not span all individual human experience.
Likewise, at the beginning of the twentieth century, the exacting edifice of physics with its precise predictions for the behavior of objects filled with huge orchestras of atoms, all crashed down to the floor. Through newly refined and highly sophisticated experimentation, the properties of individual atoms, and even the smaller particles that are contained within them, now came onto the stage, performing solo or in small ensembles, one's, two's, three's and more. The observed behavior of the individual atom was shocking to the leading scientists, who were awakening from the classical world. These new world explorers, the avant garde "poets, artists, and composers" of the modern physics of the atomic epoch, included such luminary figures as Heinrich Hertz, Ernest Rutherford, J. J. Thompson, Niels Bohr, Marie Curie, Werner Heisenberg, Erwin Schrödinger, Paul Dirac, Louis-Victor de Broglie, Albert Einstein, Max Born, Max Planck, Wolfgang Pauli, among others. This group was as shocked by what they found inside the atom as the voyagers of the starship Enterprise would have been in encountering any alien civilization across the vast reaches of the universe. The new confusion produced by the earliest data gradually gave way to desperate efforts of these scientists to restore order and logic to this new world. Still, by the end of the 1920s, the basic logic of the properties of the atom, which define all of chemistry and everyday matter, was finally constructed. Humans had begun to comprehend this bizarre new quantum world.
However, whereas the Star Trek explorers could beam up and ultimately return to less threatening spaces, the physicists of the early 1900s knew that the weird new quantum laws that ruled the atom were primary and fundamental to everything—everywhere in the universe. Since we are all made of atoms, we cannot escape the implications of the reality of the atomic domain. We have seen the alien world, and it is us!
The shocking implications of the new quantum discoveries unnerved many of the scientists who discovered them. Much like political revolutions, the quantum theory mentally consumed many of its early leaders. Their béte noire was not the political machinations and conspiracies of others, but rather deep, unsettling new philosophical problems about reality. When the full force of the conceptual revolution emerged toward the end of the 1920s, many of the originators of the quantum theory, including no less than Albert Einstein, rebuked and turned away from the theory they had a significant hand in creating. Yet, as we plunge into the twenty-first century, we now have a quantum theory that works in every situation we have applied it to, that has delivered to us transistors, lasers, nuclear power, and countless other inventions and insights. There are still strenuous attempts by distinguished physicists to find a kinder, gentler understanding of the quantum theory, less disruptive to the comfort zone of human intuition. But we must come down to dealing with science, not bromides.
The prevailing science, before quantum theory, had successfully accounted for the world of the large: the world of ladders propped safely against walls, the flight of arrows and artillery, the spinning and orbiting of planets and itinerant comets, the world of functioning and useful steam engines, telegraphy, electric motors and generators, and radio broadcasting. In short, almost all the phenomena that scientists could easily observe and measure by the year 1900 were successfully explained by this classical physics. The attempt to accommodate the weird behavior of atomic-sized things was enormously difficult and philosophically jarring. The emergent new quantum theory was totally counterintuitive.
Intuition is based on previous human experience, but even in this sense, most of the earlier classical science was itself counterintuitive to the contemporaries of its discoveries. Galileo's insight into the motion of bodies in the absence of friction was extremely counterintuitive in its day (few people had ever experienced or considered a world without friction). 2 But the classical science that emanated from Galileo redefined our own sense of intuition for the three hundred years leading up to 1900, and it seemed impervious to any radical changes. That was until the discoveries of quantum physics brought on an entirely new level of counterintuitive and existential shock.
To understand the atom, to create a synthesis of the apparently self-contradictory phenomena that came out of the laboratories in the period of 1900-1930, meant that attitudes and disciplines had to be radicalized. Equations, which on the large scale made sharp predictions about events, now yielded only possibilities, and to each possibility one could now compute only a "probability"—the probability of the actual physical occurrence of an event. Newton's equations of absolute exactitude and certainty ("classical determinism") were replaced by Schrödinger's new equations and Heisenberg's mathematics of fuzziness, indeterminacy, and probability.
How does this indeterminacy exhibit itself in nature at the atomic level? It does so in many places, but a simple example can be given here. In the lab we learn that if we have a collection of some radioactive atoms, such as uranium, half of the number of atoms will disappear (we say that they "decay into other atomic fragments") within a certain interval of time, called the "half-life." After another period of time equal to the half-life, the remaining atoms are again reduced by half (so, after two half-life intervals we have only one quarter of the original number of radioactive atoms left; after three half-lives we have only one eighth the original number; and so on). We can, in principle, with enough effort and using quantum physics, calculate the half-life of uranium atoms. Many other atomic decay half-lives can similarly be computed for fundamental particles, which keeps atomic, nuclear, and particle physicists gainfully employed. Quantum theory, however, simply cannot predict when any one uranium atom will disappear.
This is a jarring result. If uranium atoms were truly governed by Newtonian classical laws of physics, then there would be some internal mechanism at work that, with sufficient detail of study, would allow us to predict exactly when a particular atom would decay. The quantum laws are not just blind to such an internal mechanism, giving us only a fuzzy probabilistic result out of mere ignorance. Rather, quantum theory asserts that probability is all one can ever possibly know about the decay of a particular atom.
Let's consider another example of this quantum aspect of the world: if two precisely identical photons (the particles that make up light) are aimed in exactly the same way at a glass window, one or both photons may penetrate the glass or one or both may reflect back. The new quantum physics cannot predict exactly which one of the photons will do which—reflect or penetrate. We cannot, even in principle, know the exact future of a particular photon. We can only compute the probabilities of the various possibilities. We may compute, using quantum physics, that "each photon has a 10 percent probability of reflecting off the glass and a 90 percent probability of being transmitted through the glass." But that's all. Quantum physics, despite its apparent vagueness and inexactitude, provides a correct procedure, in fact, the only correct procedure, for understanding how things work. It also provides the only way to understand atomic structure, atomic processes, molecule formation, and the emission of radiation (all light we see comes from atoms). In later years it proved to be equally successful in understanding the nuclei of atoms, how quarks are eternally bound together inside the protons and neutrons of the atomic nucleus, and how the Sun generates its enormous energy output.
How, then, does the classical physics of Galileo and Newton, which dramatically fails to describe the atom, so elegantly predict exactly when solar eclipses will occur, the return of Halley's comet in 2061 (Thursday afternoon), and the exact trajectories of space vehicles?We all depend on the success of Newtonian physics to ensure that airplane wings stay attached and can fly, or that bridges and skyscrapers remain stable in the wind, or that robotic surgical tools are accurate and precise. Why does it all work so well if quantum theory says emphatically that the world really doesn't work this way after all?
It turns out that when huge numbers of atoms congregate together into large objects, as they do in all the above examples of wings and bridges, and even robotic tools, then the spooky, counterintuitive quantum behaviors—loaded as they are with chance and uncertainty—average out to the apparent proper and precise predictability of classical Newtonian physics. The short answer is that it's statistical. It's a bit like the statistically exact statement that the average American household has 2.637, residents, which can be a fairly precise and accurate statement, even though not a single household has 2.637 residents.
In the modern world of the twenty-first century, quantum physics has become the staple of all atomic and subatomic research, as well as much material science research and cosmic research. Many trillions dollars a year are generated in the US economy by exploiting the fruits of quantum theory in electronics and other areas, and many trillions more dollars are generated due to the efficiency of productivity that an understanding of the quantum world has brought forth. A few mavericks, however—physicists who are cheered on by the existentialist philosophers—are still working on the foundational ideas that define quantum theory, trying somehow to make sense of it all, hoping, perhaps, that there is a deeper inner exactitude within quantum theory that has somehow been missed. But they are in the minority.
WHY IS QUANTUM THEORY PSYCHOLOGICALLY DISTURBING?
Albert Einstein famously said: "You believe in a God that plays dice, and I in complete law and order in a world where objectivity exists, and which I, in a wildly speculative way, am trying to capture.... Even the great initial success of the quantum theory does not make me believe in a fundamental dice game, although I am well aware that your younger colleagues interpret this as a consequence of [my] senility." And Erwin Schrödinger lamented: "Had I known that my wave equation would be put to such use, I would have burned the papers before publishing.... I don't like it, and I'm sorry I ever had anything to do with it." What disturbed these eminent physicists, who turned away from their own beautiful babies? Let's examine the above complaints of Einstein and Schrödinger, often summed up as quantum theory, revealing that "God plays dice with the universe." The breakthrough that led to modern quantum theory came in 1925 when a young German, Werner Heisenberg, on a lonely vacation to Helgoland—a small island in the North Sea where the German scientist sought relief from severe hay fever—had his big idea.
(Continues...)
Excerpted from Quantum Physics for Poets by LEON M. LEDERMAN CHRISTOPHER T. HILL Copyright © 2011 by Leon M. Lederman and Chrisopher T. Hill. Excerpted by permission of Prometheus Books. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
Contents
ACKNOWLEDGMENTS....................11CHAPTER 1. If You're Not Shocked, You Haven't Understood....................13
CHAPTER 2. Before the Quantum....................41
CHAPTER 3. Light and Its Various Curiosities....................55
CHAPTER 4: Rebels Storm the Office....................83
CHAPTER 5: Heisenberg's Uncertainty....................119
CHAPTER 6: Quantum Science at Work....................149
CHAPTER 7 Controversy: Einstein vs. Bohr ... and Bell....................181
CHAPTER 8: Modern Quantum Physics....................219
CHAPTER 9: Gravity and Quantum Theory: Strings....................249
CHAPTER 10: Quantum Physics for Millennium III....................271
APPENDIX: SPIN....................289
NOTES....................299
INDEX....................329
INDEX OF FIGURES....................337