http://www.newscientist.com/news/news_223420.html
Star trekking
Voyages across the Universe have come light years closer
FASTEN your seatbelts and hold on tight--intergalactic space travel is back
on the agenda. Sceptics who dismiss the idea of faster-than-light travel
through "wormholes" in space may have to think again, because new
calculations based on Einstein's general theory of relativity suggest that
wormholes large and stable enough to allow intergalactic travel really can
exist.
The possibility that the cosmos is peppered with short cuts through space and
time has intrigued people ever since 1915 when German theorist Ludwig Flamm
found hints of their existence in Einstein's equations. While attempts to
unify the fundamental forces of nature suggest that tiny quantum wormholes
may exist, most experts suspect that some fundamental law of physics prevents
the formation of large wormholes--not least because these would theoretically
allow time travellers to go back in time and, say, prevent their own birth by
accidentally killing one of their parents.
Now a Russian theorist has found a new type of wormhole that is compatible
with the known laws of physics, yet can be as big and stable as you like.
According to Sergei Krasnikov, a relativity expert at the Pulkovo Observatory
in St Petersburg, the standard arguments against large wormholes assume that
they all have the same basic shape, and need to be crammed with "exotic
matter" to keep them open (New Scientist, 6 September 1997, p 49).
Such exotic matter has never been seen, but theory suggests it can be created
literally out of nothing when space and time are curved in the right way.
What Krasnikov has found is a new type of wormhole that can create its own
supply of exotic matter--and in sufficient quantities to make it big enough
and keep it open long enough for people to use.
"This new wormhole, like every other, needs exotic matter for it to form, and
like some others can produce it by itself," Krasnikov told New Scientist.
"What's new is that this wormhole actually generates enough to make it
arbitrarily large." Other theorists admit to being intrigued by the new work,
but remain cautious.
"It's worth taking seriously," says Ian Moss, a relativity expert at the
University of Newcastle upon Tyne. "The main worry is that it could fall down
on some technical detail." Paul Davies of Imperial College, London, adds that
proving something is theoretically possible does not prove it actually
exists: "My feeling is that the matter is still open," he says.
Krasnikov accepts that testing his claims by building a wormhole is far
beyond present technology. Even so, such wormholes may have been left over
from the big bang, he says--and finding one would have a dramatic effect on
interstellar travel: "If there is a wormhole connecting the vicinities of the
Earth and the star Vega, one can take a short cut by flying through it."
Source: http://xxx.lanl.gov/ (archive gr-qc, abstract 0003092)
Robert Matthews
>From New Scientist magazine, 15 April 2000.
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