Have had something of a physics binge lately. Started out reading Lee Smolin's Three Roads to Quantum gravity. While this is earlier than his Trouble With Physics, some of his gripes about String Theory are on display, if muted in comparison with what was to come. Still, the book was helpful for outlining Loop Quantum Gravity, which is an interesting if weird set of affairs. Also, Smolin delved into aspects of the universe as a quantum state, which was useful.
Then I read John and Mary Gribbin's biography of Richard Feynman. I find Gribbin's writing a bit cloying, but his subject was engaging enough. I'd never really 'got' Feynman; everyone seems to think he's wonderful, but his contributions seemed a bit nebulous. Turns out that he provided a different set of tools for exploring the quantum world, but didn't improve greatly on what was already known. Bit of a character though. Played the bongoes. Dreamed of visiting Tuva.
He also distrusted string theory. On the spur of the moment I bought Peter Woit's 'Not Even Wrong' - the other anti-string theory book written in 2006. I had bought Smolin's book over Woit's because Woit was a nobody in the physics world, a mathematician/spectator on these things, and felt that Smolin, as an insider would have more insight. Turns out that while Smolin's book was valuable, Woit's is probably better.
One thing in Woit's favour is his mathematical perspective, and he provides an account of 20th Century physics being informed by mathematical developments, particularly by Hilbert and Weyl, who used to hang out with Einstein, Heisenberg, and Schrodinger when they were doing their thing. Woit also doesn't pander to the reader; he describes the complex maths in detail, plunging us into the murky world of group theory and SU(6) and other crazy constructs. To be honest I couldn't tell you now what it was all about, but I felt a lot closer to what was going on, and I deeply appreciate Woit's decision not to spoon feed his readers. Mind you, some of the going was pretty dense, and Chapter 10, about recent mathematical/physical discoveries was quite bewildering.
Then we got to string theory, which Woit demolished quite expertly. As a brief rundown, string theory started out as a good idea, which quickly ran into trouble (requires 26 dimensions and faster than light particle, the tachyon). However, they manged to get it down to 9 dimensions, and could remove the tachyon if they included supersymmetry (the idea that the particles we do know about have heavier particle pairs that we don't know about). A couple of decades and several more dubious assumptions later, we have the wonderful model that sucks up so much research money and has yet to describe anything about our world that we couldn't already do with the standard model.
What amazes me is why they didn't realise they were flogging a dead horse from the start. Hidden dimensions? Relying on unproved ideas like supersymmetry? Well, it could be that the LHC does find supersymmetric particles, but string theory has so much crap welded on to it to make it work that even if they can't find supersymmetric particles a model can be conjured up that 'fits' that. The whole business is pointless, but it does keep theoretical physicists in a job for life.
Smolin and Woit advocate returning to the foundations of physics: what is time? Why is quantum mechanics so weird? Those are real mysteries, not the pipe dream fog of brane worlds and 'the landscape'.
Spurred on by my enjoyment of Woit's mathematical discourses, I've returned to Roger Penrose's imposing 1000 page monster 'The Road to Reality', with its promise of describing all of physics in all its mathematical glory for the layman. I bought this book a couple of years ago, and after the first 50 pages I felt I'd bought a $50 door stop. However, this time round I'm taking it easy, not trying to grasp every concept, but instead let the broader themes wash over me. That way, even if I never really understand maths, I'll at least learn something.
I may give you a periodic report on how I'm progressing over the next 6 months...
Posted by stuart at March 31, 2008 9:41 PM