Calculations Pop the Cork on Travel through Spacetime Tunnels

Author(s): Charles Seife

Source: Science, New Series, Vol. 300, No. 5625 (Jun. 6, 2003), p. 1489
Published by: American Association for the Advancement of Science
Stable URL: https://www.jstor.org/stable/3834436
Accessed: 02-05-2023 15:52 +00:00

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THEORETICAL PHYSICS

Catculations Pop the Cork- on Travet

Through Spacetime Tunnels NASA Weaves New Webb
It's not hard to work your way out of a hole Astronomers have been worrying that a
banish the event horizon and make the
$300 million shortfall in NASKS S1.6 billion
... a wormhole, that is. In science-fiction wormhole passable. The rules of quantum
JamesWebb Space Telescope slated for a
movies, wormholes bridges between two mechanics require that such exotic matter is
2011 launcwill force the space agency to
regions of spacetimo are handy devices for forever being created and annihilated on tiny
cancel some planned scientific instruments.
traveling halfway across the universe in the scales. Unfortunately for sci-fi buffs, how-
But a redesign and some logistical maneu-
blink of an eye. Scientists have long pon- ever, those quantum doses seemed inade-
vering has put the projectz'back in the
dered whether they were physically plausible quate to get rid of that pesky event horizon.
[budget] box" without compromising sci-
(probably, many concluded) and if so, "This made large wormholes prohibitively ence, says NASKS Richard Howard, associate
whether spaceships would be able to cross difficult to even contemplate," says Visser. director for astronomy and physics.
the bridge (probably not). Now, a team of Now it seems that the cosmic censor By using an Ariane 5 launch paid for by
physicists concludes, it might be surprisingly could be defeated. As they report in the cur- the European Space Agency, turning over a
easy to make a wormhole traversable. rent issue of Physical Review Letters, Visser guidance system to Canada, and reducing
Don't book your tickets to Andromeda and his colleagues investigated a wormhole the telescope's aperture size from 29.4 me-
yet. "We are not going to build a wormhole that is very symmetric and chugged through ters to 25 meters, Howard says NASA jS
with current technology or even confident it can deliver the observatory on
with presently foreseeable tech- budget.'We've taken a less complicated and
nology," says Matt Visser, a more straightforward approach to the in-
physicist at Victoria University struments," he says.The reduced aperture
in Wellington, New Zealand, will reduce the Webb telescope's vision
who took part in the work. But slightly, but it is still within the goal set by
he says that studying worm- agency officials and outside researchers.An
independent team will take a close look at
holes allows physicists "to take
the cost and design of the new plan this
theories we more or less under-
summer. -ANDREW LAWLER
stand [general relativity and
quantum physics], put them to-
gether, and see what breaks."
Norway Moves to Bar Human
Relativity, oddly enough, Embgyonic Stem Cell Research
stands up just fine. As out- The Norwegian government has proposed
landish as it might seem to outlawing all research involving human
move ships and people faster embryonic stem (ES) cells. The measure,
than the speed of light, Ein- which is expected to pass the legislature
stein's rules permit it because later this month, would forbid scientists
wormholes provide shortcuts from deriving new cell lines or importing
across the fabric of space and those derived elsewhere. It would be one
time. Even so, theorists sus- of the most restrictive laws in Europe
governing the controversial cells, which
pected that spacetime bridges
researchers value for their ability to
would have to exact a heavy Into the br each. A plunge down a wormhole need not be a
morph into an array of tissues.
toll. That's because relativity kamikaze mi. ission, if you bring your negative-energy matter.
The Norwegian government apparently
also shows that any wormhole
disregarded the more permissive recom-
can be turned into a time machine. By pass- extensive calculations to figure out how
mendations of an advisory group in draft-
ing through one, people might go back in much exotic matter was needed to get rid ing its law, says Steinar Funderud of the
time and kill their own ancestors before they of the event horizon. Contrary to conven-
Norwegian Radium Hospital in Oslo, who
were born, causing a paradox. tional wormhole wisdom, they found that a works with adult stem cells. But he says
So physicists were not surprised to dis- quantum-sized smidgen of the stuff could opposition to the measure has been mut-
cover that wormholes, like black holes, have make a black hole traversable. ed.^'There are no groups in Norway work-
event horizons: regions beyond which not Other wormhole researchers are cautious ing on human ES cells," he says, because
even light can escape. The event horizon, about interpreting Visser's calculations. "I'd the government will not fund such work.
sitting squarely in the throat of the worm- be a little careful in saying you need only a And patient groups that in other coun-
hole, would prevent a traveler from leaving small quantity of exotic matter" to destroy tries have lobbied strongly for the re-
the wormhole that he or she had entered. the event horizon, says Ulvi Yurtsever, a search have remained quiet in Norway.
Nature seemed to have appointed a cosmic physicist at the Jet Propulsion Laboratory in Developmental biologist Stefan Krauss
censor to prevent paradox. Pasadena. Instead he says, the equations al- of the Rikshospitalet University Hospital in
In 1988, however, physicist Kip Thorne low that the job might require a large Oslo predicts that the law will not hamper
of the California Institute of Technology in research."lt is premature to get into a huge
amount of exotic matter offset by a slightly
Pasadena and his students discovered a way controversy when there are so many open
z smaller chunk of ordinary matter.
to get rid of the event horizon. By placing questions" that can be addressed with
Even though nobody is rushing to the
mouse ES cells, he says.The law would put
a chunk of"exotic matter" with negative patent office to register their wormhole
z Norway in stark contrast to neighboring
o energy that is, less energy than an equiva- drives, theoreticians hope that traversable
Sweden, where researchers have used gov-
lent volume of empty space in the throat wormholes will at least see a bit of light at the
ernment funding to derive more than a
-
of the wormhole, a spacetime traveler could end ofthe spacetime tunnel. KHARLES SEIFE
dozen human ES cell lines.-GRETCHEN VOGEL

www.sciencemag.org SCIENCE VOL 300 6 JUNE 2003 1489

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