Martin Brown wrote in message
...
On 07/03/2011 08:22, N_Cook wrote:
Brian Cox on his prog last night twice mentioned this, as near enough
the
last throes of the dying universe - how does a black hole "evaporate"?

Hawking radiation - virtual particle anti-particle pairs occur as
fluctuations in the pure vacuum. If one falls in and the other escapes
to infinity then the black hole loses mass-energy in the process.
Casimir effect is related and observed in lab experiments.

http://en.wikipedia.org/wiki/Casimir_effect

It is amazing how early on this was measured!

Slightly less handwaving version online at:

http://casa.colorado.edu/~ajsh/hawk.html
http://en.wikipedia.org/wiki/Hawking_radiation

The lower the BH mass the higher its effective radiation temperature
which means that the final signature of a BH going pop is expected to be
quite violent. Big ones take almost forever to evaporate but are
expected to do so eventually almost everything is gone by 10^150 years.

If the existence of Hawking radiation is ever confirmed observationally
or experimentally in nano black holes made by particle physics in the
LHC then Hawking will be given a Nobel prize.

Most physicists think his model is correct, but the Nobel committee
requires experimental verification.

A restriction that they don't seem to place on the Economics prize!

Regards,
Martin Brown


I thought a definition of a black hole was that neither mass nor energy
could ever leave, so I must forget that "definition"
I liked his falling cup and falling laser beam extension of the falling
feather and lead weight under gravity , if earth was big enough to observe
both , on last night's Sky at Night

Somehow over the decades I'd never some across his first item, the Chankillo
calendar
http://hila.webcentre.ca/projects/chankillo