Cosmic Microwave Background
From Slackerpedia Galactica
The residual heat left over from the formation of the Universe, in the Big Bang. It is mostly uniform in every direction, and the shape of the spectrum is that of a blackbody having a temperature of 2.73 Kelvin.
It was discovered in in the 1960's by two Bell Laboratories engineers (Arno Penzias and Robert Wilson), who were actually trying to figure out why they couldn't eliminate all noise from microwave radio communications. At first they thought it was bird poop on their antennae, except that it didn't go away after they cleaned it off. They eventually won the Nobel Prize for discovering static, basically.
It is recently in the news again, after John Mather and George Smoot -- head honchos of the Cosmic Background Explorer (COBE) Satellite -- won the 2006 Nobel Prize for COBE's discovery. Observations of the CMB prior to COBE had proven that it was a blackbody spectrum, but nobody knew how uniform it was, nor the exact temperature (to better than a few tenths of a Kelvin). The uniformity of it was particularly important, because the lumpiness of the CMB sets limits on the lumpiness of matter in the early universe. COBE did two things: prove that the early universe was almost but not completely uniform (so the CMB is a tiny bit lumpy), and was able to measure temperatures to precisions of micro-Kelvins.
One of the funny things about the COBE result was that they were almost impossible to present in a proper graph. What I mean is that normally we put "error bars" on measurements to show how precisely they're made -- no measurement can ever be exactly right, and there's always some uncertainty in the final result. But COBE's temperature measurements were so precise that the error bars were smaller than the width of the line drawn through them, thus becoming one of the most shocking violations of astronomical precision (i.e. "a factor of two is fine...") in human history.
Earlier this year, the Wilkinson Microwave Anisotropy Probe (WMAP) carried on the work of COBE much more precisely, and put even more stringent limits on how lumpy everything is, and whether and how (and how soon) the Universe will end.
