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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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New Dimensions Within Reach?
4 August 1998 7:30 pm
The front-runner for a "theory of everything," which would corral all the known forces and particles into a single equation, is a mathematical tangle of "strings" that wander through 10 dimensions. Seen in our three-dimensional world, strings would appear as particles. Unfortunately, string theory is generally considered untestable: The seven extra dimensions are usually assumed to curl up so small that no conceivable experiment would detect them.
Now some physicists are proposing a watershed: Some of the dimensions could be as large as a millimeter and might be easily probed. "It's really profound," says University of Michigan, Ann Arbor, physicist Gordon Kane. "It's hard to say it strongly enough."
One group, who presented their work last week at the International Conference on High Energy Physics in Vancouver, Canada, looked at the possibility of loosening up the seven dimensions that the particles of the everyday world don't inhabit. Stanford University physicists Nima Arkani-Hamed and Savas Dimopoulos, with Gia Dvali of the International Center for Theoretical Physics in Italy, showed that if gravity exists in these extra dimensions, its effects could be easily detected, since gravity would be millions of times stronger at short distances than traditionally assumed. At least two tabletop experiments are planned to probe gravity's strength at distances down to a micrometer.
A second group, Keith Dienes, Emilian Dudas, and Tony Gherghetta at CERN in Switzerland, has shown how allowing a curled up dimension to unravel a bit allows three forces (the electromagnetic, strong, and weak) to unify into a single force at an energy a trillion times lower than previously thought. "Everyone thought the extra dimension would destroy the unification" and the theory, Dienes says, but add it and "bingo, the three forces unify almost immediately." If true, the strength of the three forces would have almost the same strength when probed at the Large Hadron Collider under construction at CERN.
The reaction to these ideas is mixed: "It's crazy, but it's not that crazy," says John Schwarz, a string theorist at the California Institute of Technology. Still, "it's a long shot," he says. Schwarz and others suspect an extra, "large" dimension for gravity might be inconsistent with various astrophysical measurements or with the current picture of the big bang. So far no one has been able to kill the idea. And, comments Juan Maldacena, a theorist at Harvard University: "In this field, any idea that is not obviously false is interesting."