TIME: Almanac 1990/1990 Time Magazine Compact Almanac, The (1991)(Time).iso/time/011689/01168900.003

Text File | 1990-09-17 | 6KB | 104 lines

SCIENCE, Page 55

Wormholes in the Heavens

A far-out concept leads to talk of time travel and new universes

By  Michael D. Lemonick


    Since well before Albert Einstein, physicists have been
conjuring up concepts that defy common sense. Consider just a few
of the far-out notions now accepted by the scientific community:
clocks that tick slower when they ride on rockets, black holes with
the mass of a million stars compressed into a volume smaller than
that of an atom, and subatomic particles whose behavior depends on
whether they are being watched.

    But of all the strange ideas in physics, perhaps the strangest
is the wormhole. It comes perilously close to science fiction: a
wormhole is a hole in the fabric of space and time, a tunnel to a
distant part of the universe. While no one has proved that
wormholes exist, that does not for a moment keep the more
adventurous of thinkers from trying to figure how they might
behave. Last fall, for example, three researchers from Caltech
floated the notion that in theory at least, wormholes could be time
machines.

    This week, at the American Astronomical Society's winter
meeting in Boston, physicist Alan Guth of M.I.T. will announce the
most mind-numbing wormhole-related news yet. Guth and two
collaborators have determined, he says, that "it would apparently
be possible in principle for some advanced society literally to
create an entirely new universe." The wormhole connection: such a
universe would automatically create its own wormhole, squeeze
through it, and then draw the hole closed after it.

    To many people, such theories may seem useless, if not
ridiculous. But to others, the ideas are brain teasers that both
challenge and stretch the imagination. While thinking about
wormholes has no immediate practical value, Guth insists that it
helps scientists explore how flexible the laws of physics are. More
important, the theories could shed light on some of the most
fundamental questions of cosmology: how the universe began, how it
works and how it might end.

    The idea of wormholes comes directly from the accepted concepts
of general relativity. In that theory, Einstein argued that very
massive or dense objects distort space and time around them. One
possible distortion is in the form of a tube that can lead anywhere
in the universe -- even to a spot billions of light-years away. The
name wormhole comes about by analogy: imagine a fly on an apple.
The only way the fly can reach the apple's other side is the long
way, over the fruit's surface. But a worm could bore a tunnel
through the apple, shortening the trip considerably. A wormhole in
space is the same sort of tunnel; it is a shortcut from one part
of the universe to another that reduces the travel time to just
about zero.

    Virtually instantaneous travel leads to the idea of wormhole
as time machine. If it were somehow possible to move one end of a
wormhole at nearly the speed of light, general relativity dictates
that time at that end would slow down, and that portion of the
tunnel would then be younger than the other end. Anything moving
from the faster-aging end of the wormhole to the slower would
essentially go backward in time. The mode of travel, however, could
be nothing like the mechanical time machine, complete with saddle,
envisioned by H.G. Wells. It is hard to conceive how a human being
could move through a wormhole, since it would theoretically be
narrower than an atom, and it would tend to vanish the instant it
formed.

    Just as theoretical are Guth's homemade universes. One way to
create a cosmos, he says, might be to heat a region of space to
about a thousand trillion trillion degrees. Or one might compress
some matter to densities far greater than those of a neutron star
-- a star that has shrunk to a diameter of only a few miles. "Of
course," admits Guth, "this is not only beyond the range of our
technology, but beyond the range of any conceivable technology."
It is possible only in principle, but that is what matters to
explorers on the frontiers of physics.

    Guth came to the idea of creating new universes from his
influential work on "inflationary" cosmology, which was considered
dubious when he proposed it in the early 1980s but is accepted in
modified form by most physicists today. The notion is that in the
first fraction of a second after the Big Bang, the universe, though
expanding, was still far smaller than the smallest particle now
known, and made of a peculiar stuff known as "false vacuum." Among
other odd attributes, a false vacuum generates negative gravity;
it inflates itself rapidly and enormously -- ending up as big as
a universe. Odder still, but likely nonetheless, is that everything
in our cosmos could have come from a subatomic bubble of false
vacuum with a mass of only 20 lbs. or so.

    That concept led to the idea that such a bubble could somehow
be manufactured. Classical physics says that unless this matter
started out with infinite density, it would collapse right away.
But Guth and two other physicists, Edward Farhi and Jemal Guven,
applied the more modern laws of quantum physics to the problem.
Their conclusion: the bubble might not collapse after all. It could
just possibly become a brand-new universe. Not that it would be
much good, though. Says Guth: "Such a baby universe would form a
wormhole and escape, creating its own space and time in the
process." From our universe, the new one would be completely
inaccessible, since the wormhole would pinch itself off right away.

    Such fanciful thinking may skirt the bounds of credibility,
but Guth is an intellectual test pilot. His mission is to push the
machinery of physics to its logical extremes, in hopes that he can
find out just when it will self-destruct.