Review of _Fabric of Reality_

Mark Crosby (
Thu, 7 Aug 1997 10:52:39 -0700 (PDT)

The August 7, 1997 Wall Street Journal "Bookshelf" column features Jim
Holt’s review of two new books on parallel world theories: David
Deutsch’s _The Fabric of Reality_ and Roger Penrose’s _The Large, the
Small, and the Human Mind_:

"'Ask a famous physicist what science reveals about reality and
there's no telling what sort of answer you'll get.' Stephen Hawking
will inform you that physics merely predicts observations and that it
is meaningless to talk about how it might 'correspond' to reality.
He's what's known as a positivist.

"Roger Penrose, an equally great physicist, will give you a radically
different answer. What we learn from physics, he'll say, is that the
material universe depends for its existence on a perfect world of
abstract mathematical ideas that some of us consciously commune with.
Mr. Penrose, in other words, is a Platonist.

"Then there's David Deutsch, who has unblushingly titled his
interesting new book _The Fabric of Reality_. A researcher at Oxford
and ‘an acclaimed quantum physicist’ . . . he is not in the least shy
about dismissing Hawking-style positivism as self-refuting, or
Penrose-style Platonism as a ‘a rickety fantasy.’ For his part, he is
quite sure that physics ‘tells us something new and bizarre about the
nature of reality’: namely, that we live in a ‘multiverse’ where
everything that can happen does happen.

"What makes the divergence of viewpoints . . . so wonderful is that,
far from being New Age kooks, they are three rational, hard-headed
guys who use exactly the same equations in their everyday scientific
work. The problem is that 20th-century quantum physics has an
unsettling weirdness about it. . . . This has led scientists who
insist on making sense of the world to some pretty extravagant
hypotheses. Some have lobbied for a new ‘quantum logic’ that permits
contradictions. Others have argued that reality is created by
measuring devices or by consciousness. Still others have posited a
ghostly web that allows all the particles in the universe to
communicate with one another instantaneously.

"The hypothesis that Mr. Deutsch fiercely defends - and makes the
basis of his world view - is the most extravagant of all. Dubbed the
‘many universes’ interpretation . . . According to the ‘many
universes’ view, all the quantum possibilities that determine the
outcome of subatomic events are actualities in some parallel universe.
. . . But because of the intricacies of ‘quantum interference’ (which
Mr. Deutsch does a superb job of explaining), these parallel universes
affect one another only at the tiniest level. . . .

"Does all this leave you feeling skeptical? Then, says Mr. Deutsch,
consider the quantum computer. This device - envisaged by Richard
Feynman in 1982 and largely theoretical so far, though a simple
prototype was built by IBM in 1989 - harnesses quantum phenomena to
achieve unheard of computational feats. Using something called ‘Shor's
algorithm,’ a quantum computer can factor giant numbers and thereby
break secret codes that no conventional computer could touch. The only
way it could do this, Mr. Deutsch argues, is by distributing its
operations over many parallel universes. "To those who still cling to
a single-universe world-view," he writes with evident asperity, ‘I
issue the challenge: explain how Shor's algorithm works.’

"Combining the many-universes notion with quantum computability, and
adding elements of Darwinism and Karl Popper's theory of knowledge,
Mr. Deutsch aspires to nothing less than a complete understanding of
‘the fabric of reality.’ Arrogant in tone and marred by leaps of
logic, his book nonetheless bristles with subversive insights about
virtual reality, time travel, mathematical certainty and free will.
Intellectually speaking, Mr. Deutsch is mad, bad and dangerous to know.

"So, for that matter, is Roger Penrose. In "The Large, the Small, and
the Human Mind", the English physicist tries once again to make us
share his conviction that the answer to the puzzle of human
consciousness lies in physics. . . . Even if Mr. Penrose turns out to
be wrong, he is always worth reading. In this volume - daunting as
usual, but blessedly slim - Mr. Penrose's arguments are followed by
critiques from Stephen Hawking and from philosophers of science Nancy
Cartwright and Abner Shimony . . . Mr. Hawking marvels at how Mr.
Penrose, his former collaborator on the theory of black holes, has
come to hold such different views from his on mind and reality. These
days, it seems, there's no telling a fellow's metaphysics from his

Mark Crosby

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