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[News]
In the beginning
By Marcus Chown
could the universe have been its own mother? Two
physicists in New Jersey say that this may be a
more satisfying way of explaining the origin of
the Universe than any alternatives dreamt up so
far.
Physicists have huge problems trying to work out
how the Universe got going ("The day time
began", New Scientist, 29 April 1996, p 30).
Some say the question of what happened before
the beginning of time, space and matter is like
asking what is south of the South Pole. Others
argue that the Universe has existed forever, or
somehow popped into existence out of nothing.
"We suggest that the Universe emerged from
something rather than nothing--and that that
something was itself," says Richard Gott III of
Princeton University in New Jersey. This strange
suggestion is a spin-off from the theory of
inflation which purports to describe what
happened immediately before the big bang.
In inflation, an unusual state of the vacuum
grows rapidly and exponentially. One version is
"chaotic inflation", suggested by Andrei Linde
of Stanford University in California, in which
inflating regions spawn others of their kind.
"These are baby universes which bud off from the
Universe like the branches of a tree," says
Gott.
Gott and his colleague Li-Xin Li say it's
possible that a branch of spacetime could loop
backwards to rejoin the tree trunk. "Such a
thing is possible because Einstein's general
theory of relativity permits closed time-like
curves--loops of time," says Gott.
Gott and Li found that a time loop could have
existed before the big bang without violating
any laws of physics. Space would have been in a
loop of time, perpetually re-creating itself. If
so, the Universe could be viewed as having given
birth to itself. Gott says that asking what the
first event in the Universe was becomes
meaningless. "Every event in the Universe could
have an event preceding it," he says.
One consequence of the idea is a natural
explanation for the so-called arrow of time.
Theories of general relativity and
electromagnetism do not rule out the idea that
waves can affect events that occurred in the
past. For instance, they do not forbid light
from travelling back in time.
Yet in our Universe light always travels with us
into the future. The reason, say Gott and Li,
has to do with what would happen to waves that
regressed in time in the kind of universe they
envisage. "They would travel back to the epoch
of the time loop and circle forever, constantly
reinforcing each other," says Gott. Such a
universe could not exist, Gott concludes,
because the time loop would quickly become
unstable.
"This whole area of cosmology is incredibly
speculative," comments Astronomer Royal Martin
Rees at the University of Cambridge. "But I
think this is a fascinating contribution." Gott
and Li say that they have only begun to explore
their idea and much more work needs to be done.
Their results have been submitted to the journal
Physical Review D.
related site:
* Can the Universe Create
Itself?--astro-ph/9712344
From New Scientist, 24 January 1998