From: John Clark (jonkc@worldnet.att.net)
Date: Tue Oct 02 2001 - 15:29:54 MDT
scerir <scerir@libero.it> Wrote:
>Farhi and Guth concluded that "to create conditions in a small region
>of space which would give rise to a new universe [...] would require an
>energy density that is far too high to be provided by any known technology".
According to the old ideas you'd need a particle accelerator about the size
of the galaxy to make a black hole, and in the present economic climate
you're unlikely to get a grant to make a machine that big. However there
are some new ideas that there may be more than 3 dimensions of space,
perhaps 10. The reason we don't notice the other 7 is that at small (and
perhaps not ridiculously small) dimensions they curl back on themselves.
If so then at small dimensions the attraction of gravity is proportional not to the
square of the distance as all textbooks say but to the power of 9. If so then
at small distances if you cut the distance between two particles in half the
gravitational attraction between the particles is not 4 times greater it is 512
times greater. If any of this is actually true then if would be one hell of a lot
easier to make a black hole than had been thought. If it's true that is, we should
know in just a few years.
Andrew Clough <aclough@mit.edu> Wrote:
> What sort of energies would we be talking about here?
Energies that CERN will be able to produce in 3 or 4 years.
>The cosmic rays that bombard Earth are pretty darn powerful, but I
>haven't run into any references to them causing black holes.
Cosmic rays might be making them all the time, but the smaller a black hole is
the shorter its lifetime before it evaporates by Hawking radiation. The Black Holes
we're talking about are very small and would last, I don't know, a million billion
trillionth of a second or so.
John K Clark jonkc@att.net
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