IT IS a hole that could hardly be hidden by moving the sofa. Radio astronomers have found a gigantic void in the universe, which at nearly a billion light years across is the biggest ever seen. Apparently empty of both normal matter and dark matter, the finding challenges theories of large-scale structure formation.
鈥淭he finding challenges theories of large-scale structure formation鈥�
Lawrence Rudnick and colleagues at the University of Minnesota in Minneapolis were studying data from a survey carried out by the in New Mexico 鈥� in particular a 鈥渃old spot鈥� in the map of the cosmic microwave background, or CMB. In this spot, which lies in the direction of the constellation Eridanus, the CMB photons are colder than expected.
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Rudnick鈥檚 team saw few or no radio sources within the region 鈥� indicating a void nearly a billion light years in diameter. The lack of radio sources means that there must be no galaxies or star clusters in this volume. Rudnick says that the CMB photons are cold because they have had to travel through this empty space.
