What is the Cosmic Microwave Background?
The cosmic microwave background, usually abbreviated CMB, is a form of electromagnetic radiation that permeates the entire universe. It has a temperature of 2.725K and is in the microwave portion of the spectrum (hence its name), peaking in intensity at a wavelength of 1.9 mm. The cosmic microwave background is sometimes called “the echo of the Big Bang” and is the best current evidence that the universe we live in began as a gigantic explosion from a point source. The cosmic microwave background is isotropic to 1 part in 100,000, meaning that it varies in intensity only very slightly and is for the most part homogeneous. This helps indicate that it originates from something which affected the entire universe rather than just some subset of the universe. The cosmic microwave background spectrum has the distinction of being the most precisely measured black body spectrum in nature. The cosmic microwave background radiation are photons left over from the extremely energetic time period i
