Fumbling for the key of the cosmic mechanism
Hugh Lawson-Tancred
BETWEEN INNER SPACE AND OUTER SPACE by John D. Barrow OUP, £18.99, pp. 288 What importantly happened in the 20th century? The universe grew up. New- ton's prim translation into cosmology of the architecture of Wren has become the incomprehensible monster of Hubble and his successors, while Dalton's neat atomic peas in their molecular pods have turned into Heisenberg's nebulous entities flitting in crespuscular indeterminacy from one notional existence to another.
But the permanent revolution in funda- mental physics which has kept us all on the edge of our seats since about 1905 is now hitting — guess what — budgetary constraints. Grasping the fundamental structure of matter/universe requires the generation, even if only at infinitesimal points, of concentrations of energy compa- rable to those obtaining at the 'moment' of creation. Achieving anything like this would require an expenditure roughly equivalent to crashing one stealth bomber a week for an indefinite period. Surely the money could be better spent.
It seems likely, then, that the next half- century or so will see a change of emphasis from discovery to interpretation. The cen- sus of plausible theoretical options looks at least as stable as it has done for a genera- tion, and felicitous popular advocacy has ensured that they are better recognised by the laity than their proponents might feel entitled to expect. The question, of course, is whether anyone, specialist or lay, under- stands what they mean. Can we make sense of the claim that the universe has perhaps as many as 21 dimensions, with time being a continuation of space by other means, or of the Many Worlds Hypothesis, which conjectures that the universe is constantly branching into an infinity of new, complete but mutually exclusive realisations?
You could argue that the present spate of popularisation is premature. Nobody yet has a clear enough grasp of the kerygma to act as an apostle for it. On the other hand, responsible propagation of the ineffable does much to restrain the irresponsible sort. This is certainly the view of John Bar- row, whose explanations of the constraints imposed on the initial conditions of our universe by the fact that we inhabit it and of the possible limitations of any general `unified' theory of the underlying constitu- tive symmetries of nature have established themselves as classics. In Between Inner Space and Outer Space, he serves up some intellectual tapas from the same kitchen, in which the central concerns. of his earlier work reappear as spicy and salted morsels that are perhaps a touch indigestible if taken in large doses.
Barrow broaches a generous budget of hot issues, from extra-terrestrial life to the structure of time, complexity, inflation in the early universe, quantum cosmology, science and religion and even the physics of musicality, but his central theme, which loosely unifies the entire collection, is the question which looks set to dominate the `interpretative' debate for the foreseeable future: what is the meaning of the fact that the universe is amenable to applied mathe- matics?
He addresses this enigma in a chapter entitled 'Why is the universe mathemati- cal?', which offers an admirable introducto- ry survey of the ideological turf wars that have convulsed 20th-century philosophy of mathematics, leading to a beautifully suc- cinct presentation of the fundamental choice that we face for our most abstract model of the structure of the world, the choice between symmetry and algorithm. Is the universe a pattern which we must sim- ply detect and enjoy or does it have a com- putational key with which we could ultimately unlock the housing of its inner- most mechanism? Barrow magisterially demonstrates how upon the possibility of finding such a 'cosmic code' hangs the prospect of our achieving a completely gen- eral physics. The second most rewarding part of the book after that devoted to mathematics is the discussion of time. This is hands-on popular cosmology, fighting shy of the deep conceptual paradoxes intrinsic to the vet"' notion of time, but it brings out with great clarity how talking of an 'initial point', a first moment, is highly problematic for an expanding universe. An infinite concentra- tion of matter and energy, a 'singularity'' cannot be a spatio-temporal phenomenon in any normal sense. Between Inner Space and Outer Space is an uneven collection, with a considerable amount of occasional stuff providing rather lightweight ballast, including more than 3 i full complement of reviews. However, if looked on as the obiter dicta of one of the best popular expositors of the contempo- rary Gedankenwelt of the rigorous sciences, it is consistently diverting and illuminating and indeed, at its best, hard to put down in its communication of the excitement of seeing the world as an exercise in the math- ematics of energy.
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