A Billion Billion Billion Cubic Light-Year Blank
a paper that is to appear soon in The Astrophysical Journal by astrophysicists Lawrence Rudnick , Shea Brown,and Liliya R. Williams of the U.Minn Department of Astronomy, reports that the WMAP microwave background spacecraft has detected a void in the universe a billion light years across --
"Our results suggest that the dip in extragalactic brightness and number counts and the WMAP cold spot are physically related, i.e., that the coincidence is neither a statistical anomaly nor a WMAP foreground correction problem... To create the magnitude and angular size of the WMAP cold spot requires a 140 Mpc radius completely empty void... far outside the current expectations of the concordance cosmology, and adds to the anomalies seen in the Cosmic Microwave Background" Its discovery began as a blank spot in radio telescope maps, but optical surveys saw neither galaxies or stars, and x-ray telescopes no sign of blackholes, quasars,or even dark matter.
''This is 1,000 times the volume of what we sort of expected to see in terms of a typical void,'' Rudnick told The New York Times ''It's not clear that we have the right word yet ... This is too much of a surprise.''
The Times reports Rudnick was examining a sky survey from the National Radio Astronomy Observatory, which essentially takes radio pictures of a broad expanse of the universe. But one area of the universe had radio pictures indicating there was up to 45 percent less matter in that region...The rest of the matter in the radio pictures can be explained as stars and other cosmic structures between here and the void, which is about 5 to 10 billion light years away.
Rudnick then checked observations of cosmic microwave background radiation and found a cold spot. The only explanation, Rudnick said, is it's empty of matter.It could also be a statistical freak of nature, but that's probably less likely than a giant void, said James Condon, an astronomer at the National Radio Astronomy Observatory.