Echoes from the big bang.

GRAVITY waves; COSMIC background radiation; GRAVITY; COSMIC ripples; ASTRONOMICAL observations; PHYSICS; METAPHYSICAL cosmology; BIG bang theory; INFLATIONARY universe

Although theorists have long speculated on the origin of the cosmos, until recently they had no way to probe the universe's earliest moments to test their hypotheses. In recent years leading up to 2002, however, researchers have identified a method for observing the universe as it was in the very first fraction of a second after the big bang. This method involves looking for traces of gravitational waves in the cosmic microwave background (CMB), the cooled radiation that has permeated the universe for nearly 15 billion years. The CMB was emitted about 400,000 years after the big bang, when electrons and protons in the primordial plasma--the hot, dense soup of subatomic particles that filled the early universe--first combined to form hydrogen atoms. After the CMB was discovered in 1965, researchers found that its temperature--a measure of the intensity of the black body radiation--was very close to 2.7 kelvins, no matter which direction they looked in the sky. Researchers are hoping to find direct evidence of the epoch of inflation. The strongest evidence would be the observation of inflationary gravitational waves. The key to detecting the inflationary gravitational waves is the fact that the plasma motions caused by the waves produced a different pattern of polarization than the mass inhomogeneities did. INSET: Wave Hunters.