July 31, 2006
UC Santa Cruz physicists explore a boundary
of their discipline in new book, Quantum Enigma
By Tim Stephens
Quantum mechanics, one of the most successful theories in all
of science, says some strange things about the fundamental nature
of the world. For all practical purposes, physicists can and
do ignore the bizarre implications of the theory and use the
equations of quantum mechanics to understand atoms and stars
and to create the marvels of modern technology, from computers
to flat-screen televisions. But the strangeness of quantum theory
remains an enigma at the heart of modern physics.
In a new book, Quantum Enigma: Physics Encounters Consciousness
(Oxford University Press, 2006), UCSC physicists Bruce Rosenblum
and Fred Kuttner present a clear exposition and entertaining
discussion of the baffling mysteries of quantum physics. Their
motivation, in part, was to counteract the irresponsible distortions
of quantum physics that are often used to support pseudoscientific
claims, as in the recent movie What the [Bleep] Do We
"Things like that movie upset me, but this is not a debunking
book," said Rosenblum, a professor emeritus of physics.
"A mystery in quantum physics indeed hints at some really
wild stuff. The problem is that a layperson can't tell where
the quantum physics ends and the quantum nonsense begins."
Physicists have a responsibility, he said, to be more open
and honest about the quantum enigma, which has been called the
skeleton in the physicist's closet. When Kuttner and Rosenblum
proposed a course for nonmajors on the quantum enigma, one colleague
told them that "presenting this stuff to nonscientists
is the intellectual equivalent of allowing children to play
with loaded guns." They said they'd teach gun safety, and
it's now the most popular course in the department, Rosenblum
The book presents the quantum enigma in nontechnical terms--no
scientific background is needed to grasp the essential mystery.
The aim is to give readers a sound basis for evaluating the
various interpretations that have been proposed (all of them
unsettling in one way or another) and to engage in their own
speculations. The issues raised are more philosophical than
"The quantum enigma rears up at a boundary of the physics
discipline, and beyond this boundary, a physicist flounders
just like the next guy," Rosenblum said.
Both Rosenblum and Kuttner have spent much of their careers
in industry, using quantum mechanics in their daily work. They
note that one-third of the nation's economy involves products
based on quantum mechanics.
"Physicists can use quantum mechanics and calculate with
it beautifully, but nobody understands it," said Kuttner,
now a lecturer in physics at UCSC.
The encounter with consciousness referred to in the book's
subtitle arises in the classic quantum experiments in which
physicists found that they could demonstrate contradictory things.
An atom or a molecule can be shown to be in two places at once.
That's hard enough to believe by itself, but the same atom or
molecule can also be shown to be in just one place. Looking
for it causes it to be in a single place, so that what is observed
depends on decisions made by the observer. And what is true
for atoms and molecules is, in principle, also true for baseballs
and cats, Rosenblum said.
The mystery does not emerge from quantum theory, but arises
directly from the experiments. Quantum theory provides an explanation
of sorts, in the form of equations that can be used to predict
experimental results with unfailing accuracy. The theory is
consistent with the experiments, but it conflicts dramatically
with our sense of reality.
The book presents nine current interpretations of the quantum
enigma (which physicists often refer to as the "measurement
problem"). They range from the orthodox Copenhagen interpretation
(which has been summarized as "shut up and calculate!")
to the mind-boggling many-worlds interpretation. The authors
do not endorse a favorite, but they do point out that each interpretation
either involves consciousness or tries to evade the encounter
so that physics need not deal with it.
"As far as what's really going on in the world, I don't
have a clue, except that it's much stranger than we once thought,
and somehow consciousness seems to be involved," Kuttner
Many years ago, when Rosenblum was a graduate student, he and
a fellow student got to spend an evening with Albert Einstein,
who tried to discuss the enigma of quantum mechanics with them.
But they were ill-prepared.
"Our advanced courses in quantum mechanics taught us how
to calculate, but avoided the mystery. Our ignorance of it disappointed
Einstein," Rosenblum said. "The missed opportunity
of that evening is one of the motivations behind this book.
Physics courses still avoid presenting the quantum enigma. We
would like to see our book used as collateral reading in such