OFF: SETI, ETs

[M Holmes]

Andy Gilham writes:

> Steve Hawking did come up with something recently that suggested that
> backward time travel may be possible in certain limited circumstances, but I
> think it was of the order of nanoseconds in the vicinity of a naked
> singularity, or some such.

I read some stuff on this recently and it seems that the math doesn't
preclude time travel backwards. However, you can't go back to before the
Universe started :-)

A corollary of the same math is that it should be possible in principle
to establish wormholes in space simply by using either gravity or
electromagnetic forces to bend space. The black holes idea is of course
related to using gravity for this purpose. The problem is that tidal
forces (different gravity on one side of your spaceship from the other)
will tear you apart.

Another way to do this would be with very strong electromagnetic fields.
Apparently there are topological problems with setting up the two ends
of the wormhole.  However, someone worked out that if such things were
set up and they were came between the Earth and a a star or galaxy,
there'd be a kind of double version of the effect they get with
gravitational lensing (black holes and other superdense objects get
between the Earth and a distant galaxy and lens the image in a
particular way which is detectable by producing a double-image). Since
there are searches for gravitational lensing underway, they added
software to search fro this signature also, just in case they discovered
an ET subway system :-) Apparently there was some excitement a couple of
months back when they got such a result, but it was explained by some
other mechanism. Meanwhile another ETI search continues.

I *think* this appeared in Scientific American sometime over the last year.

> - Andy

FoFP