Cosmic microwave background is the ancient light imprinted on the sky when the universe was about 370,000 years old. Today faint traces of this ancient light yet linger upon our vision, yet remarkably it is not evenly spread out across our universe. Extremely small fluctuations in this shroud of light which make it appear to be clotted are in fact the seeds from which grew the galaxies we see about us today.
The universe began in a hot, dense state which initially exploded outward at a rate far exceeding that of the speed of light. Then it began to cool as it expanded...and here we are.
