It is the "left over" light after the big bang took place. It used to have a much short wavelength but it has stretched over the 14 billion years that the universe has been expanding.
For much more detail, go to the related link below.
cosmic microwave background radiation.
Primordial background radiation is in actuality Cosmic Microwave Background. To discover just what Cosmic Microwave Background theories are, visit the URL posted below:http://www.astro.ucla.edu/~wright/CMB.html
this is radiation in the microwave part of the electromagnetic spectrum which comes from all directions in outer space
1965.
The evidence of cosmic microwave background radiation supports the Big Bang theory.
cosmic microwave background radiation.
microwave background radiation is a thermal radiation left from the early stage of universe when it was much small and much hotter and filled with uniformly distributed opaque fog of hydrogen plasma
Microwave (Cosmic background radiation).
cosmic microwave background radiation
Where? Everywhere. This is the residual radiation, from when the Universe was very, very hot.
The spectral distribution of cosmic microwave background radiation follows a blackbody spectrum with a temperature of approximately 2.7 Kelvin. It peaks in the microwave region of the electromagnetic spectrum, with a characteristic wavelength of around 1 mm. This radiation is considered a key piece of evidence supporting the Big Bang theory.
In the 1960s, microwave radiation was detected coming from space and no particular source, and this radiation was dubbed the Cosmic Microwave Background Radiation (CMBR).