One of the main pieces of evidence in support of the Big Bang theory is the existence of the cosmic microwave background (CMB). The CMB refers to an isotropic, meaning the same in all directions, radiation bath that permeates the entire universe. The existence of the CMB was discovered in 1965 by Arno Penzias and Robert Wilson with the help of a well-calibrated horn antenna. The radiation was diffuse and spread uniformly in all directions in the sky something that Penzias and Wilson could find no complete explanation for. They considered the signal to have been affected by undetermined systematic noise of the presence of pigeon droppings in the horn. Douglas Scott and Martin White (2010) discuss that confirmation of the existence of the CMB
It soon came to their (Penzias and Wilson) attention through Robert Dicke and Jim Pebbles of Princeton that this background radiation had in fact been predicted years earlier by George Gamow as a relic of the evolution of the early Universe. This background of microwaves was in fact the cooled remnant of the primeval fireball- an echo of the Big Bang.
The universe, being extremely hot and dense at one point, would have formed plasma from its photons and baryons. As the universe expanded and simultaneously cooled, a point was reached where the photons decoupled from the matter. Dr. Gary F. Hinshaw of NASA (2010) explains Today, the CMB radiation is very cold, only 2.725 degrees above absolute zero, thus the radiation shines primarily in the microwave portion of the electromagnetic spectrum and is invisible to the naked eye.
The spectrum of the radiation is almost identical to that of a black body or a perfect radiator. The temperature is uniform to better than one part in a thousand. By the early 70s, it was discovered that the CMB is cooler in one direction, while hotter in the opposite direction. There is, however, only a minute temperature difference between the two directions (0.1 of the overall temperature).
It soon came to their (Penzias and Wilson) attention through Robert Dicke and Jim Pebbles of Princeton that this background radiation had in fact been predicted years earlier by George Gamow as a relic of the evolution of the early Universe. This background of microwaves was in fact the cooled remnant of the primeval fireball- an echo of the Big Bang.
The universe, being extremely hot and dense at one point, would have formed plasma from its photons and baryons. As the universe expanded and simultaneously cooled, a point was reached where the photons decoupled from the matter. Dr. Gary F. Hinshaw of NASA (2010) explains Today, the CMB radiation is very cold, only 2.725 degrees above absolute zero, thus the radiation shines primarily in the microwave portion of the electromagnetic spectrum and is invisible to the naked eye.
The spectrum of the radiation is almost identical to that of a black body or a perfect radiator. The temperature is uniform to better than one part in a thousand. By the early 70s, it was discovered that the CMB is cooler in one direction, while hotter in the opposite direction. There is, however, only a minute temperature difference between the two directions (0.1 of the overall temperature).
No comments:
Post a Comment