From: Michael S. Lorrey (retroman@turbont.net)
Date: Sat Mar 18 2000 - 10:54:52 MST
hal@finney.org wrote:
>
> Robert J. Bradbury, <bradbury@aeiveos.com>, writes:
> > a) What is the photonic density required to create a black hole
> > and do any of the principles of photon interaction prevent
> > this from focusing laser beams to produce a black hole?
> > [I may have asked this before, but I'm too lazy to go check
> > the archives.]
>
> In our previous discussion, I think I found some references from
> sci.physics which indicated that no intensity of photons would create
> a black hole, if they are all going in the same direction. The answer
> was complicated for other cases.
>
> > b) If you have particles (electrons, protons, etc.) circulating
> > in a syncrotron, emitting syncrotron radiation, shouldn't
> > they eventually "evaporate" into nothing? Or is it always
> > true that the photons they are emitting get replenished by
> > the external power source?
>
> An electron won't evaporate. The radiation it emits must be coming from
> the EM fields accelerating in the synchrotron.
>
> > c) Why do astronomers, esp. X-ray astronomers, often quote the
> > temperatures of gas clouds in "millions" of degrees? If the
> > atom/molecule densities are on the order of a few per cc
> > I don't see how you can get temperatures like this. Temperature
> > corresponds to vibration or molecule velocity, but what is
> > the relationship between ionization state and temperature?
> > Is the effect of increasing temperature -- atom ionization
> > then acceleration of the ions? If so, then what would be
> > the "temperature" of an electron gas?
>
> I'm not sure about what this actually means, but presumably there are
> two choices. (1) the gas cloud is emitting black body radiation and
> really has a temperature of millions of degrees. (2) the gas cloud is
> emitting non-thermal radiation of some sort, whose peak is in the range
> that would correspond to a black body temperature of millions of degrees.
>
> There is nothing in principle preventing (1) from being true, but it
> is hard to see what energy source could get it so hot, since the Sun is
> only a few thousand degrees. Perhaps some kind of magnetic interaction
> could super-heat the cloud.
or radiation from nearby stars. interstellar gas is not a black body, so
even if it were in the millions of degrees it would not necessarily
correspond to black body radiation typical of a black body that is at
millions of degrees.
Mike Lorrey
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