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Richard Lea: Too attached
The Times Literary Supplement, 8.2.1

THE TROUBLE WITH PHYSICS. The rise of string theory, the fall of a science 
and what comes next. By Lee Smolin. 416pp. Penguin. Paperback, Pounds 
8.99. - 978 0
14 101835 5. US: Mariner Books. $15.95. - 978 0 618 91868 3.

In his critical examination of string theory, The Trouble with Physics, 
Lee Smolin has launched a controversial attack on those working on the 
dominant model in theoretical physics. He accuses string theorists of 
racism, sexism, arrogance, ignorance, messianism and, worst of all, of 
wasting their time on a theory that hasn't delivered.

Smolin begins by setting out the five major problems confronting 
theoretical physicists at the beginning of the twenty-first century, 
problems that seem to indicate that a radically new type of theory is 
required. According to Smolin, these problems constitute the unfinished 
business of the twentieth century's revolution in theoretical physics, 
begun by Albert Einstein with his twin discovery of general relativity and 
quantum mechanics. These two theories divide the world into two regions. 
General relativity is a theory of the very big, which describes how matter 
bends space and time. Quantum mechanics is a theory of the very small, 
which describes how matter and energy are split up into tiny chunks. In 
their separate realms, each has been extremely successful, but they are 
totally incompatible. The first problem facing twenty-first-century 
physics is to combine gravity and quantum mechanics into a single theory 
which can explain phenomena that are both big and small.

The foundations of quantum mechanics are Smolin's second problem. He 
believes that quantum theory's refusal to describe nature beyond what is 
observed leaves it as an incomplete description of reality, and that any 
solution to the other problems will require a "sensible" replacement for 
quantum mechanics, despite the steady drip of experimental results placing 
ever stricter limits on just how "sensible" such a replacement can be. 
Smolin's third problem is to determine whether the four forces of nature 
(gravity, electromagnetism and the strong and weak nuclear forces) can be 
explained as aspects of a single, underlying entity - though, again, it is 
gravity that is causing the trouble.

The masses of the particles and the strengths of the forces that act 
between them form the fourth of Smolin's unanswered questions. A theory 
that could explain why quarks and leptons come in families, or why gravity 
is so much weaker than the other forces, would have much to recommend it. 
His fifth and final puzzle comes from recent results in cosmology, and 
appears at first sight to be unrelated to the other four; but the 
indications that all the types of particle found on earth seem to make up 
only 4 per cent of the matter density of the universe may turn out to be 
an important clue.

Smolin then sets off on a historical tour of scientific revolutions, 
drawing out "lessons for would-be unifiers" along the way: "mathematical 
beauty can be misleading"; "when someone proposes the right unification, 
the implications become obvious very quickly"; "a real revolution often 
requires that several new proposals for unification come together to 
support one another". The story of the century since Einstein is mapped 
out in failed attempts at unifications - Kaluza-Klein theory, quantum 
gravity, SU(5) grand unification. Each time, the same moral is drawn out. 
For a unification to be successful, it must draw together things that seem 
to be different, and at the same time explain why they appear at first 
glance to be distinct.

The stage is now set for Smolin's presentation of string theory, which he 
does with the clarity and enthusiasm of one who has spent years working in 
the field. The basic idea of superstring theory is to replace the 
unphysical, zero-dimensional point particles of the standard model of 
particle physics with tiny, vibrating strings. The vibrations of the 
strings - the notes they are playing - provide the different types of 
particles we see in the standard model. The ways they can break and join 
together provide the different forces that act between them. The 
attractions of this manoeuvre are considerable. It solves the third and 
fourth of Smolin's five major problems at a stroke: all the forces, all 
the particles in the standard model, are just strings wobbling.

But, according to Smolin, the downsides are even greater. The trouble with 
string theory is that consistency with special relativity and quantum 
mechanics requires extra spatial dimensions. The world we live in has only 
three directions - up, down and side to side. String theory seems to 
require an extra six.

The fact that we cannot see these extra directions is not necessarily a 
fatal flaw. If some of the nine directions are curled up small enough, we 
would not be able to perceive them after all. And the precise details of 
the ways in which six directions are squashed together offer a chance of 
pulling off the second half of the unification project, a chance to 
explain why it is that the particles and forces look so different even 
though they all come from strings.

A dizzying variety of theories now results, whose workings are so 
fiendishly difficult that thirty years of work and two major breakthroughs 
later, no one can say for sure that a consistent theory actually exists.

Smolin then spends the next sixty pages mapping out alternatives, focusing 
mainly on an intriguing suggestion he is working on for unifying gravity 
and quantum mechanics called loop quantum gravity, before returning to 
examine string theory's dominant position within theoretical physics. He 
describes an arrogant, cult-like sect imbued with a tremendous 
self-confidence, dominated by a few strong leaders, which values 
mathematical facility over original thought.

According to Smolin, string theorists show little interest in work going 
on outside string theory, a "cavalier" attitude to distinguishing between 
conjectures and results, and an avoidance of risk, though he offers no 
convincing account of how such a sinister cabal has managed to seize 
power. He tries repeatedly to depersonalize his attack, stressing that he 
admires and respects both individual string theorists and much of their 
work, but it would be naive to suppose that such assurances carry much 
weight with those whose professional lives are under assault.

A quick detour into the philosophy of science offers a just-so story which 
describes science as a community of sceptics, a story advanced with a 
cheerful optimism and unthinking realism that will hearten and dismay 
philosophers of science in equal measure. Smolin follows Thomas Kuhn in 
dividing science into "normal" and "revolutionary" phases, and suggests 
that different types of scientist are needed for each phase. Until 
consensus is established, "seers" are needed to come up with a wide range 
of approaches to outstanding problems.

When the evidence "forces consensus", "master craftspeople" can then 
rapidly achieve results with the agreed theoretical machinery. According 
to Smolin, the problems that confront twenty- first-century physics 
require a generation of seers, but physics departments are structured to 
produce a generation of craftspeople. He sketches a few proposals for 
reform that would be hard to disagree with - "young scientists should be 
hired and promoted based only on their ability, creativity and 
independence"; "people who invent and develop their own research 
programmes should be given priority"; "people should be penalized for 
doing superficial work that ignores hard problems" - and some that seem 
arbitrary or impractical: "when there is a recalcitrant but key problem, 
there should be a limit on the proportion of support given to any one 
research programme that aims to solve it - say, a third of total funding". 
He finishes with an appeal to scientists, department heads and the general 
public to think for themselves.

It is difficult for the non-specialist to come to an opinion about the 
merits of differing approaches to resolving the outstanding problems in 
theoretical physics, but that should not deter readers - it is difficult 
for theoretical physicists to decide themselves. One of the most 
attractive features of The Trouble with Physics are Smolin's descriptions 
of what it is like to do theoretical physics. His encounters with 
physicists who have other ideas give an inkling of the excitement of new 
insights; his decisions about which avenues he should pursue give an 
indication of the difficulties in being confronted with an intellectual 
choice that could determine the future course of your career. He compares 
working in string theory to "doing your income tax every day, all day, for 
a week, and still not getting the calculations to add up consistently". 
Theoretical physics is hard. The problems with string theory may be 
nothing more than a reflection of its difficulty - and there is no reason 
to suppose that the universe is constructed so that it is easy to work out 
how everything fits together - or they may be because of some fundamental 
flaw. At the moment there is no way of telling. Smolin's homespun account 
of how science works is no help to us now. String theory seems unlikely to 
produce a workable theory of everything any time soon, exerts an influence 
on the academy and on the popular imagination quite out of proportion to 
its questionable successes, and may well turn out to be nothing more than 
an interesting dead end. There are certainly other approaches worth 
exploring - I have a hunch Smolin's suggestion that time needs some 
attention has something in it - but it is worth remembering that nobody is 
forcing young scientists to become string theorists.

Smolin has little new to say about how the institutions of science are 
undermined by personal ambition, internal politics and bureaucratic 
overload - as he himself admits. Designing institutions that are 
transparent and robust is also hard. Finding and rewarding the candidates 
who can think in new ways that are not only radical but also useful is a 
problem that confronts even the software companies and music conglomerates 
of which he is so enamoured. The "seer" who comes up with the fundamental 
insights needed to resolve the unfinished business of twentieth-century 
physics is as likely to be found outside the academy as within it. The 
Trouble with Physics offers an engaging take on the state of fundamental 
theoretical physics, mercifully free of the thumbnail character sketches 
that dog much popular science, and is all the more readable for its 
unashamedly partisan nature. While talk of a "crisis" in physics is surely 
overblown - physics goes on peaceably in neighbouring fields after all - 
it is perhaps unsurprising that a guide who really knows the territory 
does not scruple to take sides when talking about a local dispute.