Spudboy100@aol.com writes:
> In a message dated 7/6/00 2:09:54 AM Pacific Daylight Time, asa@nada.kth.se
> writes:
>
> << Tipler et al. actually once proved some powerful theorems about open
> universes, showing that it was not possible to close them by
> rearranging the matter inside. >>
> In his Theory of Immortality, though, he does give an example of how very
> tiny amounts of energy, over a very long time can rearrange matter in order
> to close the universe in two directions. That example was using a
> butterfly's energy to move the earth from one side of it's orbit around the
> sun to the other side-in about 500 million years!
That is not the same thing. Yes, you can move around the matter in the
universe quite a bit using small impulses and a lot of time and
cleverness. But the theorem actually says you cannot close an open
universe no matter what, it has to do with the spacetime topology and
cannot be changed by merely (say) piling all the matter into a big
ball or something similar. To make matters worse, we have a
cosmological constant to deal with too. Of course, quantum gravity and
such things may complicate things enough to enable closure, but that
remains in the realm of wishing for the moment.
> <<Sure, but that is not good evidence for Tiplers position. If he had
> made a plausible sketch of such a system or showed some theorem that
> implied the existence of high-energy complex systems he would be on
> much steadier ground. Now he is just assuming that it must be
> possible, a bit like a space program assuming that before landing we
> will have come up with a way of landing softly...>>
>
> Well, what Tipler left out, Hans Moravec put in, with his Neutron Star
> computers-or neutronium computations-however one wants to state this.
Well, a neuron star is a nice thing when you want to resurrect your
relatives all the way back to pre-dynastic Egypt and other small
projects :-) But it doesn't give you the real, infinite
calculations/memory storage, Omega Point. Accept no substitutes :-)
> One of the great failures over the last 55 years has been the
> failure to produce a successful, commercial, fusion power plant. My
> point is that at least with tokamaks and stellerators, the greatest
> physical problem is plasma "turbulence" or variation of the plasma
> stream; which tends to quench the super-hot reactions needed to
> produce workable reactors. Call this a serendipity of scientific
> discovery; but such turbulence or variations, can be considered
> "primordially" to be usable as a kind of super-hot computer--in the
> great, great, distant future. Its utility today might be analogous
> to an antimatter-powered pacemaker; doable, but why-ever-fore?
That plasma can be chaotic does not prove that it can be used to
perform useful calculations. I'm not aware of any proofs that plasma
chaos is of the right kind to be Turing-complete, but I can imagine it
is. However, a real physical (nuclear) plasma is a different thing,
and may very well have diffusion or randomness effects that disrupts
the computations.
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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