Cosmic microwave background radiation
Cosmic microwave background radiation (CMB radiation) is radiation in the microwave part of the electromagnetic spectrum, which comes from all directions in outer space. It is known to come from our earliest infant universe. Since the universe is very large, and the speed of light is constant, we know that when the CMB light arrives from the infant universe, it arrives as the oldest signal that we can detect.
During the Big Bang, a lot of high-energy radiation was created. Then, the universe became bigger and colder. Therefore, the high-energy photons lost most of their original energy. Now, as a result, that radiation is in the microwave part of the electromagnetic spectrum (the microwave part has quite low energy). The cosmic microwave background is the radiation that has been traveling without hitting anything ever since the time the universe became transparent, about 380,000 years after the Big Bang.
Arno Penzias and Robert Wilson first detected the CMB radiation.[1] Scientists think that the existence of CMB radiation is important evidence, with red shift, that the Big Bang theory is true.
Later data is based on the Planck spacecraft operated by the European Space Agency (ESA). It was designed to observe differences in the cosmic microwave background (CMB) at microwave and infra-red frequencies, with high sensitivity and small angular resolution. The spacecraft has finished its work, but researchers are still analyzing the data. The main interest is that there is:
- "an asymmetry in the average temperatures on opposite hemispheres of the sky. This runs counter to the prediction made by the standard model that the Universe should be broadly similar in any direction we look. Furthermore, a cold spot extends over a patch of sky that is much larger than expected".[2]
No explanation for this is known.
Cosmic Microwave Background Radiation Media
Nine-year Wilkinson Microwave Anisotropy Probe heat map of temperature fluctuations in the cosmic microwave background
Graph of cosmic microwave background spectrum measured by the FIRAS instrument on the COBE, the most precisely measured black body spectrum in nature. The error bars are too small to be seen even in an enlarged image, and it is impossible to distinguish the observed data from the theoretical curve.
The Holmdel Horn Antenna on which Penzias and Wilson discovered the cosmic microwave background. The antenna was constructed in 1959 to support Project Echo—the National Aeronautics and Space Administration's passive communications satellites, which used large earth orbiting aluminized plastic balloons as reflectors to bounce radio signals from one point on the Earth to another.
Artist impression pf the gravitational lensing effect of massive cosmic structures
