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Cosmic Microwave Background Radiation

Cosmic Microwave Background Radiation - Big Bang At the...

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Cosmic Microwave Background Radiation George Gamov (lived 1904--1968) predicted in 1948 that there should be a faint glow left over from when the universe was much hotter and denser. Since the universe is observed to be expanding, it means that the galaxies were originally right on top of each other. Also, the energy of the universe was concentrated in a smaller volume. The entire universe would have glowed first in the gamma ray band, then the X-ray band, then to less energetic bands as the universe expanded. By now, about 14 billion years after the start of the expansion, the cold universe should glow in the radio band. The expansion rate has slowed down over time because of the force of gravity. This means that the early expansion was faster than it is now. At the start of the expansion, the expansion rate was extremely rapid. The early large expansion rate and very hot temperatures made Fred Hoyle (lived 1915 - 2001) call this theory of the birth of the universe, the
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Unformatted text preview: Big Bang . At the time he coined the term, Hoyle was advocating another theory that used the perfect cosmological principle called the Steady State theory. So at the time, Hoyle's "Big Bang" term was made in joking disdain. However, the Big Bang proponents liked the term and used it from then on. Observation Arno Penzias and Robert Wilson observed in 1965 a radio background source that was spread all over the universe---the cosmic microwave background radiation . The radiation has the same intensity and spectral character as a thermal continuous source at 3 K (more precisely, 2.728 ± 0.004 K) as measured by the COBE satellite in every direction observed. To a high degree of precision the sky is uniformly bright in radio. The uniformity of the background radiation is evidence for the cosmological principle. The error bars in the figure below are too small to be seen....
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Cosmic Microwave Background Radiation - Big Bang At the...

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