- Smolin, Lee.
The Trouble with Physics.
New York: Houghton Mifflin, 2006.
ISBN 0-618-55105-0.
-
The first forty years of the twentieth century saw a
revolution in fundamental physics: special and general
relativity changed our perception of space, time, matter, energy, and
gravitation; quantum theory explained all of chemistry
while wiping away the clockwork determinism of
classical mechanics and replacing it with a deeply
mysterious theory which yields fantastically precise
predictions yet nobody really understands at its deepest
levels; and the structure of the atom was elucidated, along
with important clues to the mysteries of the nucleus. In
the large, the universe was found to be enormously larger
than expected and expanding—a dynamic arena which
some suspected might have an origin and a future vastly
different than its present state.
The next forty years worked out the structure and interactions
of the particles and forces which constitute matter and
govern its interactions, resulting in a standard model of
particle physics with precisely defined theories which predicted
all of the myriad phenomena observed in particle accelerators
and in the highest energy events in the heavens. The universe
was found to have originated in a big bang no more distant than
three times the age of the Earth, and the birth cry of the universe
had been detected by radio telescopes.
And then? Unexpected by almost all practitioners of high energy
particle physics, which had become an enterprise larger by far than
all of science at the start of the century, progress stopped. Since
the wrapping up of the standard model around 1975, experiments have
simply confirmed its predictions (with the exception of the discovery
of neutrino oscillations and consequent mass, but that can be
accommodated within the standard model without changing its
structure), and no theoretical prediction of phenomena beyond the
standard model has been confirmed experimentally.
What went wrong? Well, we certainly haven't reached the End of
Science or even the End of Physics, because the theories which govern
phenomena in the very small and very large—quantum mechanics and
general relativity—are fundamentally incompatible with one
another and produce nonsensical or infinite results when you attempt
to perform calculations in the domain—known to exist from
astronomical observations—where both must apply. Even a
calculation as seemingly straightforward as estimating the energy of
empty space yields a result which is 120 orders of magnitude
greater than experiment shows it to be: perhaps the most
embarrassing prediction in the history of science.
In the first chapter of this
tour de force, physicist
Lee Smolin poses “The Five Great Problems in
Theoretical Physics”, all of which are just as mysterious
today as they were thirty-five years ago. Subsequent chapters
explore the origin and nature of these problems, and
how it came to be, despite unprecedented
levels of funding for theoretical and experimental physics,
that we seem to be getting nowhere in resolving any of these
fundamental enigmas.
This prolonged dry spell in high energy physics has seen the emergence
of string theory (or superstring theory, or M-theory, or whatever
they're calling it this year) as the dominant research program in
fundamental physics. At the outset, there were a number of excellent
reasons to believe that string theory pointed the way
to a grand unification of all of the forces and particles of physics,
and might answer many, if not all, of the Great Problems. This
motivated many very bright people, including the author (who, although
most identified with loop quantum gravity research, has
published in string theory as well) to pursue this direction. What is
difficult for an outsider to comprehend, however, is how a theoretical
program which, after thirty-five years of intensive effort, has yet to
make a single prediction testable by a plausible experiment; has
failed to predict any of the major scientific surprises that have
occurred over those years such as the accelerating expansion of the
universe and the apparent variation in the fine structure constant;
that does not even now exist in a well-defined mathematical form; and has
not been rigorously proved to be a finite theory; has established
itself as a virtual intellectual monopoly in the academy, forcing
aspiring young theorists to work in string theory if they are to have
any hope of finding a job, receiving grants, or obtaining tenure.
It is this phenomenon, not string theory itself, which, in the
author's opinion, is the real “Trouble with Physics”.
He considers string theory as quite possibly providing clues (though
not the complete solution) to the great problems, and finds much to
admire in many practitioners of this research. But monoculture is
as damaging in academia as in agriculture, and when it becomes deeply
entrenched in research institutions, squeezes out other approaches
of equal or greater merit. He draws the distinction between “craftspeople”,
who are good at performing calculations, filling in blanks, and extending
an existing framework, and “seers”, who make the great
intellectual leaps which create entirely new frameworks. After
thirty-five years with no testable result, there are plenty of reasons
to suspect a new framework is needed, yet our institutions select out
those most likely to discover them, or force them to spend their most
intellectually creative years doing tedious string theory calculations at the
behest of their elders.
In the final chapters, Smolin looks at how academic
science actually works today: how hiring and tenure decisions are
made, how grant applications are evaluated, and the difficult
career choices young physicists must make to work within this system.
When reading this, the word “Gosplan”
(Госпла́н)
kept flashing
through my mind, for the process he describes resembles nothing so
much as central planning in a command economy: a small group of
senior people, distant from the facts on the ground and the cutting
edge of intellectual progress, trying to direct a grand effort in
the interest of “efficiency”. But the lesson of more
than a century of failed socialist experiments is that, in the timeless words
of Rocket J. Squirrel, “that trick never works”—the
decisions inevitably come down on the side of risk aversion, and are
often influenced by cronyism and toadying to figures in authority.
The concept of managing risk and reward by building a diversified
portfolio of low and high risk placements which is second nature
to managers of venture capital funds and industrial research and
development laboratories appears to be totally absent in academic
science, which is supposed to be working on the most difficult and
fundamental questions. Central planning works abysmally for cement and
steel manufacturing; how likely is it to spark the next scientific
revolution?
There is much more to ponder: why string theory, as presently defined,
cannot possibly be a complete theory which subsumes general
relativity; hints from experiments which point to new physics beyond
string theory; stories of other mathematically beautiful theories
(such as SU(5) grand unification) which experiment showed to be dead
wrong; and a candid view of the troubling groupthink, appeal to
authority, and intellectual arrogance of some members of the string
theory community. As with all of Smolin's writing, this is a joy to
read, and you get the sense that he's telling you the straight story,
as honestly as he can, not trying to sell you something. If
you're interested in these issues, you'll probably also want to read
Leonard Susskind's pro-string
The Cosmic Landscape
(March 2006) and Peter Woit's sceptical
Not Even Wrong
(June 2006).
September 2006 