The Quantum Moment: How Planck, Bohr, Einstein, and Heisenberg Taught Us to Love Uncertainty

287 Pages·2014·3.11 MB·English

by  Robert P. Crease

The
Quantum Moment
How Planck, Bohr, Einstein, and Heisenberg
Taught Us to Love Uncertainty
Robert P. Crease
Alfred Scharff Goldhaber
W. W. Norton & Company
New York • London
To our students, whose spirit and insight enlivened our course and this book
Contents
Introduction
1. The Newtonian Moment
Interlude: The Grand Design
2. A Pixelated World
Interlude: Max Planck Introduces the Quantum
3. Quantum Leaps
Interlude: Niels Bohr Uses Quantum Leaps to Make Atoms Go
4. Randomness
Interlude: Albert Einstein Shows How God Plays Dice
5. The Matter of Identity: A Quantum Shoe That Hasn’t Dropped
Interlude: Wolfgang Pauli and the Exclusion Principle, Satyendra Bose
and Bosons
6. Sharks and Tigers: Schizophrenia
Interlude: Erwin Schrödinger’s Map/Werner Heisenberg’s Map
7. Uncertainty
Interlude: The Uncertainty Principle
8. Reality Fractured: Cubism and Complementarity
Interlude: Complementarity, Objectivity, and the Double-Slit Experiment
9. No Dice!
Interlude: John Bell and His Theorem
10. Schrödinger’s Cat
Interlude: The Border War
11. Rabbit Hole: The Thirst for Parallel Worlds
Interlude: Multiverses
12. Saving Physics
Conclusion: The Now Moment
Notes
Acknowledgments
Credits
Index
The Quantum Moment
Introduction
Not long ago, the two of us were in a classroom listening to our students give
their final presentations, which had to consist of original work. Two students
read short plays; one performed a hip-hop song; others created artwork in
various media. One student, who was being treated for schizophrenia, explained
—bravely, haltingly—what it was like to suffer from the disease, using the
language of superposed states in quantum mechanics, bringing the typically
boisterous and chatty class to dead silence. The next presentation was by a pair
of science majors who donned safety goggles, poured liquid nitrogen on a
special kind of magnet which is a Type II superconductor, and demonstrated
“quantum levitation,” explaining the Abrikosov-Meissner effect on which it is
based. In between, students made jokes about references to quantum topics that
they’d found, including web pages about things like “quantum beer” and
“quantum jazz.” The last project was by a mechanical engineering major. He
brought a stack of odds and ends that he said he had thrown together—Pepsi
bottles, eyeglasses, Scotch tape, a Ping-Pong ball—to the front of the room. He
astounded the class by shining a flashlight on the stack from a particular
perspective—and it projected the clear image of a cat against the wall.
These projects were the final assignment for The Quantum Moment, a class
that we’ve cotaught for half a dozen years. An elective open to physics and
philosophy majors, it attracts a diverse range of students. Humanities students
who take it are intrigued about what the word “quantum” means. Science
students who take it want to know whether and why a scientific term can really
be applied to human behavior. Other students are drawn by the catchy title or
because the course satisfies certain requirements and fits their jammed
schedules.
Cat by Juan Mesa.
The course is about the cultural impact of the quantum. The quantum, the
name for the fact that energy comes in finite packages and is not infinitely
divisible, was introduced in 1900 to explain puzzling results in a remote corner
of physics about how light is emitted and absorbed. Two quantum revolutions
followed. The first occurred between 1900 and 1925, when scientists discussed
and developed the theory without attracting much public attention. Then, in
1925–27, the theory was transformed by a second revolution, called quantum
mechanics, whose bizarre implications became the subject of public curiosity
and discussion. Even today, over eighty years later, humanity is still unsure what
to make of the second quantum revolution, finding it puzzling, visionary, and
even shocking. New books about the quantum appear almost monthly. The word
quantum is applied to everyday life in plays, poetry, movies, paintings, fiction,
music, philosophy, numerous company names, and “pop science” approaches to
psychology and neuroscience. Heisenberg’s uncertainty principle, Schrödinger’s
cat, parallel worlds, and other concepts and images of quantum mechanics show
up on T-shirts and coffee cups, in cartoons, novels, poems, and movies. They are
found on failblog.org, a showcase of cultural memes. In the American television
drama series Breaking Bad, “Heisenberg” is the pseudonym of the protagonist, a
high school chemistry teacher who manufactures and sells the illegal drug
crystal methamphetamine. In March 2012, a New York Times opinion article
argued that quantum terminology was the correct way to describe the campaign
and personality of presidential candidate Mitt Romney: “For we have entered the
1
age of quantum politics; and Mitt Romney is the first quantum politician.”
President Barack Obama, who defeated Romney in the November 2012 election,
in interviews has invoked Heisenberg’s principle to explain how he seeks
guidance from advisers. In the twenty-first century, we ask our class, why does
the idea of the quantum still appear as a metaphor in the human realm—wild and
mysterious, packed with creative force?
Our readings vary from semester to semester but include books and articles
on history, philosophy, and sociology, several plays (including Michael Frayn’s
Copenhagen), and have included works of fiction (such as Neal Stephenson’s
Anathem). We provide background for how diverse concepts and images—the
uncertainty principle, complementarity, Schrödinger’s cat, parallel universes—
sprang from the quantum idea. We ask students to think carefully about how
quantum language and imagery is used and abused. In the article entitled “How
You Get That Story: Heisenberg’s Uncertainty Principle and the Literature of the
Vietnam War,” what insight does this reference add to understanding
journalism? Is the use of parallel worlds in movies such as Another Earth and
Rabbit Hole an incisive semiscientific plot twist or distracting ornament?
The students’ final projects involve creating, singly or in groups, a quantum-
inspired work of their own. In addition to the ones already mentioned, they have
also written songs, created multimedia presentations, decorated clothing, and
created performance “art” by spouting or spoofing quantum nonsense. One year,
students made a video about a second-year physics major (played by a second-
year physics major), trying to learn the meaning of quantum mechanics. He goes
into Stony Brook’s Physics Help Room—an actual place!—hoping a good tutor
will be on hand that day. An English major (played by an English major) rushes
up to him:
ENGLISH MAJOR. “Thank God you’re here! I have to tell somebody! I just read this article on
quantum mechanics—you’re never going to believe this—with Newton everything was certain, but
now with quantum mechanics nothing is certain anymore! There’s this Heisenberg uncertainty
principle and, I mean, I could go outside and there’s not even an outside. . . . I left my dorm today
and it was sunny and now (pointing to her umbrella) it’s probably raining.
PHYSICS MAJOR, exasperated. It’s a beautiful day outside, I promise.
ENGLISH MAJOR. Everything is uncertain now. With Newton it was fine and now it’s not fine
anymore. . . . Am I a particle or a wave? Are you even real?
PHYSICS MAJOR, irritated. You’re fine, I’m fine, your hamster’s fine, your dorm’s fine.
ENGLISH MAJOR, suddenly widening her eyes. My hamster! My dorm! . . . I don’t know what
my hamster is doing right now . . . It’s all a mess—
Physics major writes “WHY ME?” in his notebook, stands up, and leaves the room.
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One of us is a physicist, the other a philosopher. The physicist (Goldhaber)
teaches an introductory course on the foundations of quantum mechanics: the
now quite complete and well-understood theory of matter and energy based on
the discovery that, at the subatomic scale, energy comes in amounts of finite
size. This remarkable theory has yet to make a prediction that has been proven
wrong. The philosopher (Crease) teaches courses that explore the implications of
this theory for concepts such as space, time, causality, and objectivity. Our
course came about because the two of us often discussed our bafflement with the
way scholarly and popular language is sprinkled with references to “quantum
this” and “quantum that,” sometimes in the form of genuine insights, at other
times of meaningless buzzwords designed to impress or dazzle.
Initially, we assumed the cultural impact of the quantum was largely
inconsequential, and that we would mostly find terms and images used by
charlatans to impress the gullible, and artists with a dash of scientific literacy
who appropriated the cultural authority of science. We found that quantum
language and images are indeed often used in humorous, pretentious, wacky, and
exploitative ways. But we also noticed that the quantum appeared to provide
important new terms and ways of thinking about human beings and the world
that have become second nature. We were startled to discover the range of ways
in which quantum language and imagery have permeated our world. Quantum
(Latin for “how much”) and its plural form quanta continue to appear in
conventional ways springing from the word’s origin, one example being in the
title of the still often cited “Quanta Cura,” an 1864 Papal encyclical written by
Pius IX long before quantum mechanics. The title is taken from the document’s
first few Latin words, and means “With how much care.” But after the