[extropy-chat] Krasnikov: hyperfast travel/ time machines

[Hal Finney]

On Thu, 06 Jan 2005 21:39:28 -0600, Damien Broderick wrote:
> http://arxiv.org/PS_cache/gr-qc/pdf/9511/9511068.pdf
> http://arxiv.org/abs/gr-qc/9508038

Basically this describes an improved version of the (in)famous Alcubierre
warp drive, a hypothetical construction for FTL travel using exotic
features of General Relativity.  Krasnikov's analysis shows however that
the Alcubierre warp can't be generated by the ship, it would require a
series of external stations to warp space as the ship went past.

He shows that it is impossible for a ship-carried warp drive to get
from point A to point B faster than light.  However, surprisingly, it
is not impossible in principle to fly the round trip from A to B back
to A faster than light.  Basically it is done by having the ship warp
space on the outbound leg, so that on the return leg it is going back
through the space it warped.  This allows Alcubierre-like effects to
occur even with an on-ship drive.

However there is no specific mechanism proposed that could do this,
rather he just establishes that it is not inconsistent with GR.

Hal