What is cosmic background wave radiation and how it provides Evidence for Big Bang ?
The big bang, as I’m sure you know, took the form of,what appears to be, an explosion. More accurately, it was a rapid expansion of space itself. The temperature was enormously high, so high in fact that the sub-atomic particles were moving so fast that they could not form atoms. That meant that the matter consisted of plasma containing positive and negative particles. Any light, in the form of photons, could not travel very far before interacting with a charged particle of some sort. When the universe was about 300,000 years old, it had cooled enough to allow for the formation of atoms, which are electrically neutral. That meant that light photons could travel around as free entities. But the universe was still very hot. As it continued to expand, i.e. as space itself continued to expand, the wavelength of the light started to expand with it. If you draw a wavy line on a rubber sheet and then stretch the sheet, the wavy line stretches with it so the wavelength gets longer. Scientists
