From: Mike Lorrey (mlorrey@yahoo.com)
Date: Wed Jan 22 2003 - 20:04:47 MST
--- "Eliezer S. Yudkowsky" <sentience@pobox.com> wrote:
>
> I'd expect the Sun's light to slowly diminish along a curve, rather
> than
> blink out all at once. So even if it blinked out hundreds of
> thousands of
> years ago, it will shine long enough for my purposes.
>
> But I've heard thousands, not millions. *google google*. Okay,
> millions.
> http://www.ucolick.org/~mountain/AAA/answers/physics/ph10.html
> http://www.howstuffworks.com/sun2.htm
>
> From http://www-astronomy.mps.ohio-state.edu/~dhw/Intro/lec7.html
> >
> > If we divide the heat energy of the sun's atoms by the observed
> luminosity of the sun (the rate at which this energy escapes), we
> find that the sun's energy supply would be exhausted in about 30
> million years.
> >
> > The sun can replace some of this energy by gravitational
> contraction (which increases the central pressure and therefore heats
> up the gas in the middle), but this process can only increase the
> lifetime by about a factor of two.
This is in serious error. If fusion shut down, the retained heat of the
sun may last 30 million years, but there is certainly enough hydrogen
(which will fuse to helium, which will fuse to lithium, etc) for a few
billion more years of fusion. Thus, the above is in error in calling
the latent heat the sun's 'energy supply', since it is the mass of the
sun which is it's supply. The latent heat is rather a sink or reserve
of heat.
=====
Mike Lorrey
"Live Free or Die, Death is not the Worst of Evils."
- Gen. John Stark
"Pacifists are Objectively Pro-Fascist." - George Orwell
"Treason doth never Prosper. What is the Reason?
For if it Prosper, none Dare call it Treason..." - Ovid
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