The Trouble with Physics: The Rise of String Theory, The Fall of a Science and What Comes Next

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The Trouble with Physics: The Rise of String Theory, The Fall of a Science and What Comes NextLee Smolin

Brave, spirited rearguard action

If only more scientists wrote for popular audiences with the humility Lee Smolin does. Whilst he occasionally gets bogged down in the detail of his own material — there are more minutiae on particle physics here than most people will care for in a bedtime read — Lee Smolin’s major points are clearly made and they ring like a bell.

In some ways this is a work of popular philosophy of science, not popular science itself: Smolin approaches his subject through the prism of the failings of string theory to coagulate over the last thirty years, but only in the loosest sense is this an attempt to prove string theory wrong and his own favoured research programme, quantum loop gravity, right. For one thing, he accepts from the outset that there are significant issues with his own programme.

Smolin’s concern is more around the practice of modern physics; how the gradual disappearance of anything resembling testable empirical evidence has given way to ever more theoretical modelling which in turn has led to hypotheses of increasingly incredible (literally, that is) implications. For any variety of string theory to work (it is more of a cluster of similar possible theories, rather than a discrete theory as such) the mathematics require something like *eleven* spatial dimensions, some of which, it is variously hypothesised, must be so small as to be conceptually unobservable (the image we are invited to consider is dimensions which curl up into little donuts smaller than an atomic particle across), or which appear to require an infinity of alternative universes — a “multiverse” if you will — into which these dimensions can be projected. (I may well have not understood or expressed this perfectly: the important point is that the theory must account for the absence of any physical evidence for the extra dimensions: solution — they’re invisible, of course!)

Smolin’s concern is not just that these are outlandish and faintly ridiculous consequences — though they surely seem to be — but precisely that they are systematically untestable. By definition there is no means to measure spatial dimensions smaller than the smallest subatomic particles. By definition we cannot see or measure physical effects occurring outside our own universe. These are not just difficult to say with a straight face, Smolin argues, but by any commonly understood sense of the term they’re altogether unscientific: logically closed, untestable, unfalsifiable, unreliant on any kind of inductively gathered argument.

Precisely the sort of arguments, in other words, that give religious cosmologies a bad name: utterly verboten, you would think in the enlightened mead-hall of the physical sciences. (Yet, and without apparent irony, biologist Richard Dawkins makes favourable reference to the “multiverse” theory in his recent book The God Delusion.)

Smolin argues that this uneasy development collides head-on with some uncomfortable realities about the sociological aspects of the practice of science. Again, Smolin is persuasive here (though in my case preaching to the choir) in citing favourably the late, anarchic, philosopher of science Paul Feyerabend, whose general message is that for scientific methodology anything goes, and all theories have a role to play for the good of the “development of knowledge", and that determined insistence on an existing accepted theory for framing ongoing research hardens quickly and dangerously into dogma: you need the vistas that different theories offer, says Feyerabend, or they are “as useless as a medicine that heals a patient only if he is bacteria-free".

For his trouble, Smolin is duly criticised for exhibiting “postmodernist” or “relativist” tendencies, and while I don’t think this is a criticism myself, it is in any case unfairly awarded, since Smolin avowedly retains a belief in the possibility of objective truth, and promises to (but in the end doesn’t really) take issue with the work of the most celebrated “postmodernist” philosopher of science, Thomas Kuhn. (I’m a fan of Kuhn’s so I was looking forward to the challenge, and was a bit disappointed to find it didn’t materialise).

Practically, Smolin feels that String Theory is now a “paradigm in crisis". Certainly, the theoretical tail seems to be wagging the practical dog. It is difficult to see what practical utility a theory has which postulates invisible dimensions and which doesn’t seem to point with any clarity to a possible solution at all, let alone one with the elegance of an F = ma or an E = mc2.

I suspect this book will annoy the hard-core science-is-truth crowd, but anyone with a more open mind will find a valuable perspective here.