Monday, September 15, 2014

A Quick One While I Am Away

A dandy guy in complex Hilbert space

I've been looking around for a nice authoritative foundation of quantum mechanics that isn't too interpretative. The classics are Dirac, von Neumann (haven't read...) and Feynman. I've got a couple books, including Messiah (which I haven't read...) a book called "A First Course In Quantum Mechanics", Roger Penrose's amazing but super thick Road To Reality (really good on complex analysis! I don't know so much about physics). And there's a lot of really nice things like this.

This guy again. People are going to start getting annoyed.

Feynman is very dedicated to an ... interpretation of physics. Maybe style would be a better word than interpretation. Not just quantum mechanics, but all of physics. Feynman's ontology is that everything is particles, even fields are particles. This makes some things nice and some cruel and wicked. In addition, field theory is really pretty, especially if you take out that distracting physics. This very local view of reality was called by philosopher David Lewis the "Humean Mosaic", but Feynman by denying the existence of fields goes far beyond this. Lewis's strong localism doesn't deny that fields exist because field have totally local interpretations, as demonstrated by Weyl somewhere. (Pro-tip: if you ever have a physics theorem you know is true but can't prove it at the moment, say Weyl did it and you'll probably be right). The question is whether this interpretation gives us anything extra. Working with fields can make some things a lot easier. For instance, a static magnetic field outside a superconductor in the Meissner state is obviously a variation on Laplace's Equation because the field has to be zero on the super conductor. This is obvious if you think in terms of fields, but it is more mysterious (but still true) if you think in terms of the microscopic interactions on the surface superconductor.

I'll let you all go with some music:

See you soon!

No comments:

Post a Comment