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The Universe Might Be Hanging on a StringNew cosmic string discovery claim to be tested |
By Gabriel Gache, Science News Editor
19th of January 2008, 10:34 GMT
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String theory predicts that the universe could be populated with entities of pure mass-energy called cosmic strings, which are basically defects in the space-time fabric that are create while spacetime suffers
a rapid change in phase. Such changes in phase might have taken place in the early stages of the universe, during the Big Bang.
String theory abandons the classical belief that elementary particles are point-like objects, and predicts that they are actually strings of energy vibrating at different frequencies, which also gives them their flavor. Cosmic strings, on the other hand, are thought to be oscillating at frequencies close to the speed of light, which causes the string of energy to form an isolated loop. Although they have limited lifespans as they decay through gravitational radiation, it is mostly believed that some might exist even today.
If they exist, cosmic strings would have extremely low diameters, somewhere in the range of the proton's size, and massive density that would produce a powerful source of gravitational fields. The string theory calculates that a cosmic string only 1.6 kilometers long would have a gravitational field stronger than that of Earth, and could in fact reach masses comparable to that of the Sun.
The University of Sussex and Imperial College of London have discovered what they think that might be a cosmic string, stretching across the whole universe. Similar claims had been posted previously, such as the observation of a gravitational lensing effect that could have been associated with the presence of a cosmic string. However, the Hubble Space Telescope showed that what seemed to be the double image of a single galaxy actually were two separate galaxies in a distant region of the universe.
In order to test the evidence brought by the recent study, the WMAP probe is currently creating an accurate map of the whole universe by observing the intensity of the Cosmic Microwave Background, in all directions. If cosmic strings do exist, then the WMAP probe will be able to see the predictions made by the string theory.
According to Dr. Mark Hindmarsh, the cosmic strings cannot be viewed directly, but he is positive that they exist in many numbers in the remote regions of the universe. By making observations on the CMB, the cosmic rays and gravitational lensing or radiation effects, we might be able to prove that the cosmic strings exist, which would probably be the first evidence of a string theory prediction.
By making simulations on how these entities might interact with the surrounding medium, the so-called COSMOS team made predictions of the visible effects produced on the CMB by the presence of cosmic string. Nevertheless, Hindmarsh is optimistic, even if the WMPA won't be able to detect a cosmic string, ESA's Planck Satellite will be launched this year, fact that will give scientists a second chance to prove the string theory.
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