26 Jul
2009
26 Jul
'09
6:50 p.m.
Date: Sun, 26 Jul 2009 17:14:22 -0400 (EDT) From: Dan Asimov <dasimov@earthlink.net>
It does seem Rowan and Harold were discussing *classical* mechanics. (Can there be theoretical newtonian black holes? Actual ones?)
I recall going to a seminar at MIT in the 1990s by Unruh about what he at the time called "dumb holes". They're supposed to be the acoustic equivalent of a black hole. It involved a suersonic fluid flow into a sink. Because the fluid flows supersonically, no sound can propagate upstream out of the hole. So it's "dumb" -- in the sense of unable to make a sound -- just as black holes are classically unable to radiate. http://en.wikipedia.org/wiki/Dumb_hole