The huntfor elusive gravitationalwaves has a new target: singing cosmic superstrings which emit thelong-sought waves as they vibrate.
Thesuperstrings are "so light that they can't have any effect on cosmic structure,but they create this bath of gravitational waves just by decaying," said CraigHogan, a cosmologist with the University of Washington (UW).
Gravitationalwaves, ripples of gravity caused by moving matter as it warps the fabric ofspace and time, were first theorized by Albert Einstein in his theory ofgeneral relativity in 1916, though the phenomena have yet to be observed inreal time.
Stringtheory--posits that hidden dimensions are tightly wound in strings ofelementary particles. An offshoot of this theory--suggests that some suchstrings can form into narrow tubes of energy stretched across vast distances bythe expansion of the universe. These theoretical cosmic superstrings, which researchersdescribed as ultra-thin tubes filled with ancient vacuum created in the earlyuniverse, can coil into galactic-sized, vibrating loops that emit gravitationalwaves as they decay into oblivion.
They might alsobe detectable using the LaserInterferometer Gravitational Wave Observatory (LIGO) or NASA's proposed LaserInterferometer Space Antenna (LISA), Hogan added.
"Sensingthese vibrations would add the soundtrack to the beautiful imagery of astronomythat we are used to seeing," Hogan said. "All this time, we have been watchinga silent movie."
Hogan andMatt DePies, a UW doctoral student and visiting physics lecturer, presentedcalculations for cosmic superstring-generated gravity waves this week at ameeting of the American Astronomical Society in Seattle.
Sincegravitational waves are thought to be extremely weak, cosmologists believe thatonly those generated by massive collisions will be strong enough to beobserved.
A blackhole smash up, for example, could spew waves of up to a million times themore power than those produced by every galaxyin the universe, researchers said.Hogan added that while some gravity ripples could occur at frequenciesperceptible to the human ear, many sources are likely to have extremely lowfrequencies of 10 to 20 octaves below the range of human hearing.
"If we seesome of this background, we will have real physical evidence that these stringsexist," Hogan said.
Editor'sNote: Allweek, SPACE.com is providing completecoverage of the 209th meeting of the American Astronomical Society.
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