* Peter da Silva wrote:
> They used to think the same thing about negative numbers, and irrational
> numbers. We're already secure with the rules breaking down at one kind of
> singularity, and there's even a mechanism by which that singularity can
> be exposed... I see no reason why a limited singularity in *time*, with
> limits on its range, can't be similarly accepted.
If you mean the singularities predicted by GR, then no, I don't think
people are happy with that. The impression I got when I was doing
(not completing...) a PhD in GR was that singularities are pretty
serious deficiencies in the theory which will be avoided at some
future time by some quantum gravity theory. Certainly any theory that
relies on differentiability but predicts breakdowns of
differentiability has some bad problems.
Neither my maths nor physics is now up to working out how toxic
causality violating solutions are, but I still have this really bad
feeling about them.
In general I'm also uncomfortable with the idea that one might want to
invoke something as nasty as CV really just because of some unease
about QM. QM has no real problems outside people's heads -- it agrees
with all the experiments, and generally it works wonderfully well. It
even has models (many worlds) which get rid of the whole
classical/quantum measurement dilemma. It's just a bit weird, that's
all. (Note that QM also *saves* you from differentiability breakdowns
in electrodynamics, which is cool.)
Anyway this is now well beyond the limit of what I cen remember so I'm
done I think.