From: Anders Sandberg (asa@nada.kth.se)
Date: Fri Jun 28 2002 - 07:28:40 MDT
On Thu, Jun 27, 2002 at 01:02:46AM -0400, Spudboy100@aol.com wrote:
> http://xxx.lanl.gov/PS_cache/gr-qc/pdf/0206/0206078.pdf
>
> This is a fairly, tasty, Closed Timelike Curve Paper, which is worth a view,
> for those cosmologically-inclined. An 8 page paper with short, interesting,
> observations about the Alcubierre Warp Drive and Krasnikov Solutions.
A nice review, but it doesn't really propose anything new, just
show that CTCs are copping up all over the place and that there is
no easy way out.
If the consistency principle holds, then interesting things could
happen. If you create a system with a CTC it might not be useful to
make paradoxes, but the consistent states around it could likely be
used for some forms of computation. For example, generate a random
number and try dividing a given number with it; if it does not
divide it evenly you send back a signal that would prevent the
computation. Hence quantum mechanics will only allow the process to
produce factor states (and possibly malfunction states).
Essentially you get an O(1) factoring algorithm, and quite a few
other algorithms can be speeded up similarly even if the CTC can
only transfer one bit (it doesn't even have to be usable for
communication, it just have to be a CTC that can affect previous
world states somehow). While sounding somewhat fanciful, it is not
really that different from ordinary quantum computation.
Another interesting issue is whether consistency can be used as a
physical building block. Alaistair Reynolds mentions an ISO in
_Revelation Space_ held up against gravitation by a CTC: if it
implodes the CTC that caused it will not happen, so quantum
consistency forces it to remain in place. While the building method
he suggested sounds a bit unlikely, the core idea seems promising.
Every constraint can be used as a building block.
-- ----------------------------------------------------------------------- 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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