Subject: categories: Re: cracks and pots

From: "Robert J. MacG. Dawson" <[email-masked]>
Date: Fri, 17 Mar 2006 14:29:16 -0400

jim stasheff wrote:
>
>
> Robert J. MacG. Dawson wrote:
>
> And, as you know, there are
> still scales, almost a century later,  on which its predictions are
> unsatisfactory.
>
> For us ignorant of these, please explicate.

	(1) At the very small scale, nobody has really managed to unify quantum
mechanics (which is as thoroughly tested on its home turf as relativity
is on its own) with general relativity. QM works astonishingly  well on
the atomic scale, GR works astonishingly well on the astronomical scale,
but there is a big gap, "in which we live", in which neither is
particularly evident and classical Newtonian mechanics   works pretty
well for most purposes.

	(2) At very large scales there is some question as to whether
additional forces, not predicted by general relativity, are needed to
explain some cosmological observations. This is more speculative, but a
lot of physicists seem to think *something* needs to be done.

	-Robert