Clark, list,
Thanks for the link, I failed to supply any. Even in cases where
Wikipedia is to be trusted, it's often too technical and jargony, as if
written by students for their professors rather than by professors for
the general public.
You wrote, "...Noether’s Theorem would imply non-conservation in
classical (nonrelativistic) physics..." - I think you meant that
Noether’s Theorem would imply conservation in classical
(nonrelativistic) physics.
For my part I should have added that, according to general relativity,
the total energy increases in an expanding universe and decreases in a
contracting universe. I get scared of saying physical-theoretical things
like that because I worry that there's some key caveat or the like that
I don't know about.
> [CG] No idea how this relates to Peirce though. I assume he just
assumed classical physics.
The issue may be relevant to Peirce because he did assume classical
pre-Einsteinian physics in discussing physics. Part of his discussion of
life, absolute chance, and triadicity in nature depends on the idea that
energy is conserved.
Best, Ben
On 9/30/2014 7:42 PM, Clark Goble wrote:
On Sep 30, 2014, at 2:05 PM, Benjamin Udell <bud...@nyc.rr.com
<mailto:bud...@nyc.rr.com>> wrote:
Regarding conservation of energy: My understanding is that, in
general relativity it's considered not to be conserved in an
expanding or contracting universe, although it's still regardable as
conserved in normal situations with some assumptions beyond those in
special relativity.
Stack Overflow Physics does a good job on this
http://physics.stackexchange.com/questions/296/is-energy-really-conserved
Basically while Noether’s Theorem would imply non-conservation in
classical (nonrelativistic) physics, within GR you can’t define a time
direction. However in GR you have something called global
hyperbolicity which leads to the same sort of result as Noether’s
Theorem gives in classic physics. Sean Carroll over at Cosmic Variance
dealt with this in a nice way a few years back.
http://blogs.discovermagazine.com/cosmicvariance/2010/02/22/energy-is-not-conserved/
I’m no cosmologist so this was new to me as I didn’t recall it from my
GR text. I’d always just assume Noether’s Theorem held. Once it was
explained it made complete sense though.
No idea how this relates to Peirce though. I assume he just assumed
classical physics.
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