A DIFFERENT UNIVERSE
Reinventing
Physics
From the Bottom Down.
By Robert B. Laughlin.
Illustrated.
254 pp. Basic Books. $26.
EVERY child knows how to learn what makes a toy work: bust it open. In that
sense, we're all born reductionists, whose philosophy holds that anything can be
explained by breaking it into its component parts. By analyzing them, one
discovers how the parts act together to produce larger phenomena. If you crack
open a windup clock, you can examine its gears to see what makes it tick.
Some people resent reductionism because it sweeps away many mysteries. Behind
spooky phenomena, reductionists have shown, are the ordinary ticktocks of
nature's machinery, the concealed ropes and pulleys of cosmic-scale Penn and
Teller tricks. Indeed, reductionism has reinforced the old philosophical
suspicion that there is something vaguely unreal about ''reality'': as the Greek
philosopher Democritus said, it's all just atoms and the void. To a
hyper-reductionist, the invisibly small microworld is more ''real'' than
everything else. Bigger objects -- cats, toasters, people, the sun, galactic
superclusters -- are just second-order consequences. The atoms or quarks or
leptons (or ''strings,'' if you follow the latest trendy theories) are what
count, while you and I are just ephemera.
It's a disillusioning view, but so far it has yielded undeniable benefits. By
breaking matter into atoms, subatomic particles and subatomic forces, and by
disassembling living organisms into such discrete elements as cells, genes,
enzymes and so forth, scientists have learned much about how nature works, and
how we can make it do our bidding.
Inevitably, reductionism has been overused. Not everything can be reduced to
cosmic nuts and bolts. In the emerging sciences of the 21st century, many
researchers are dusting off an old saying: ''The whole is more than the sum of
its parts.''
A recent example: many molecular biologists once thought the chemical
information stored on DNA coded for the full complexity of living organisms. But
a few years ago, the Human Genome Project revealed people have far too few genes
(not many more than a roundworm) to account for the kaleidoscopic complexity of
the human body. By itself, it appears, DNA cannot explain it any more than you
can infer the United States Constitution from the traffic laws of Topeka.
Somehow, biologists propose, higher-level ''organizational'' or ''emergent''
principles switch on at larger sizes, such as on the scale of proteins.
Even physicists, wizards of the nonliving realm, are talking about emergent
properties. Their change of heart is not easy, though, as Robert B. Laughlin,
who received a Nobel Prize in Physics, shows us in his important, brain-tickling
new book, ''A Different Universe.'' Like the blacksmith to whom everything
resembles a nail, some physicists spent decades trying to explain everything in
terms of particles; thus, gravity was attributed to a hypothetical ''graviton.''
In recent decades, though, a few physicists have won acclaim for experiments
with antireductionist implications. One example is a bizarre laboratory
phenomenon called superfluidity, in which liquefied helium crawls vertically out
of its beaker like the gelatinous monster in ''The Blob.''
Laughlin, who teaches at Stanford University, illuminates emergent principles
through a charming analogy: the paintings of Renoir and Monet. Up close the
paintings look like ''daubs of paint,'' nothing more. Yet when we step back from
the canvases, we see fields of flowers. ''The imperfection of the individual
brush strokes tells us that the essence of the painting is its organization.
Similarly'' -- Laughlin adds in a most unexpected segue -- ''the ability of
certain metals to expel magnetic fields exactly when they are refrigerated to
ultralow temperatures strikes us as interesting because the individual atoms out
of which the metal is made cannot do this.''
A major step toward recognition of emergent phenomena was a discovery about
electrical conductivity in 1980 by the German physicist Klaus von Klitzing. To
understand its significance, be aware of its historical context: in the 19th
century Edwin Hall had discovered principles of electrical conductivity usually
called the Hall effect, and for a century afterward electrical conduction had
been understood as simple Newtonian motion of electrons in a metal.
Von Klitzing found a totally unexpected phenomenon -- that Hall conductivity
in strong magnetic fields and ultralow temperatures changes in a precise,
stepwise fashion as the field strength is varied. What identifies the effect as
emergent is its precision and the fact that it disappears in small samples. The
Nobel Prize in Physics awarded to him in 1985 specifically cites this work.
Laughlin and two colleagues shared the 1998 prize for their studies of a similar
phenomenon, one even more bizarre than von Klitzing's, ''unanticipated by any
theory and not analogous to anything previously known in nature,'' as Laughlin
writes.
Talk of emergence makes many scientists nervous. The word, after all, has
been co-opted by all kinds of people who have bowdlerized it, along with once
precise terms like ''holistic'' and ''paradigm,'' for trivial purposes. More
pertinent, emergence seems to defy common sense, just as the notion of the
sphericity of the earth once did. There are no emergent principles in money, for
example: 100 million pennies equals $1 million, not an emergent $2 million. To
our primate brains, the whole is the sum of its parts. But when I once griped
about the counterintuitiveness of quantum physics, a scientist at the University
of Illinois replied dryly, ''Common sense is a poor guide to the nature of
reality.''
Laughlin's thesis is intriguing, if not completely persuasive. I can't help
wondering if hard-core reductionists will eventually explain emergent phenomena
in reductionist terms; they've pulled rabbits out of hats before. Still, his
thesis reminds us of the great value of something most physicists assume they
can live without: philosophy. Behind the seemingly concrete principles,
practices and instruments of any laboratory, there are certain philosophical
assumptions, often unexamined. In the 19th century physicists were hypnotized by
the myth of the cosmic ether, an invisible medium through which light rippled,
as waves ripple across a pond. In 1905, Albert Einstein, then a young patent
clerk, awakened them. Likewise, Laughlin says, physicists face a philosophical
''crisis'' over emergence, ''a confrontation between reductionist and emergent
principles that continues today.'' In the history of science, philosophical
crises often precede scientific revolutions.
This year is the 100th anniversary of Einstein's revolution. In Laughlin's
view, another physics revolution is coming. He mocks speculations in the 1990's
about an imminent end of science: ''We live not at the end of discovery but at
the end of Reductionism, a time in which the false ideology of human mastery of
all things through microscopics is being swept away by events and reason.'' To
invoke a familiar metaphor, physicists have fruitfully spent the last century
trying to map every twig, acorn and bird's nest in the trees. Now it's time to
step back and see the forest.
Keay Davidson, a science writer for The San Francisco Chronicle, is the
author of ''Carl Sagan: A Life.''
Published: 06 - 19 - 2005 , Late Edition - Final , Section 7 , Column 1 ,
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