Mapping the microwave background.About 20 years ago the discovery of the cosmic background of microwave radiation, which comes to us from all directions and appears to represent blackbody radiation at 2.7 kelvins, brought the Big Bang theory big bang theory n. A cosmological theory holding that the universe originated approximately 20 billion years ago from the violent explosion of a very small agglomeration of matter of extremely high density and temperature. Noun 1. of cosmology out of the shadows and made it the standard cosmology. In recent years continuing evidence that the background is strictly isotropic Refers to properties that do not differ no matter which direction is measured. For example, an isotropic antenna radiates almost the same power in all directions. In practice, antennas cannot be 100% isotropic. , the same in all directions, has necessitated serious revisions of the Big Bang big bang Model of the origin of the universe, which holds that it emerged from a state of extremely high temperature and density in an explosive expansion 10 billion–15 billion years ago. , the so-called inflationary Big Bang theories. The latest addition to the evidence, published by Philip Lubin, Thyrso Villela, Gerald Epstein ( now at the Office of TEchnology Assessment in Washington, D.C.) and George Smoot of the Lawrence Berkeley (Calif.) Laboratory in the Nov. 1 ASTROPHYSICAL JOURNAL LETTERS, involved measurements at a wavelength of 3.o millimeters taken during four balloon flights -- three from Palestine, Texas, and one from Cachoeira Paulista, Brazil. They covered 85 percent of the sky and enabled the observers to make a map of the sky that indicates overall isotropy isotropy the quality or condition of being isotropic. and supports current inflationary Big Bang theories. The well-known dipole anistropy, which is interpreted as being due to a motion of our local group of galaxies and is not a cosmological problem, does appear. According tok it, this group is moving at about 550 kilometers per second toward a point at right ascension 10.7 hours and declination declination, in astronomy, one of the coordinates in the equatorial coordinate system. The declination of a celestial body is its angular distance north or south of the celestial equator measured along its hour circle. -22[deg.]. This point is about 44[deg.] away from the center of the Virgo cluster, our nearest cluster. Quadrupole A quadrupole is one of a sequence of configurations of electric charge or gravitational mass that can exist in ideal form, but it is usually just part of a multipole expansion of a more complex structure reflecting various orders of complexity. anisotropies, which have been reported by other observers and which would be a cosmological problem, do not appear in these data. |
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