The Big Bang |
As the Universe cooled down from the hot Big Bang, it radiated energy much like a glowing fireplace poker. The radiation started with short, high energy wavelengths that gradually lengthened as it cooled. Scientists have calculated that from a start of trillions of degrees, over the vast age of the Universe it has cooled down to something just under 3 Kelvin. At this present temperature, this cosmic energy pervades the Universe with radiation in the millimeter wavelengths, peaking at just over one millimeter.
This is the Cosmic Microwave Background Radiation (CMBR) astronomers observe in all directions of the sky and is one of the main pieces of evidence in support of the Big Bang theory.
You can observe the CMBR yourself. Turn on a TV, preferably in a darkened room. If the TV is attached to cable, switch the input to antenna. Then turn the station to a channel with no signal -- a blank channel. Increase the contrast in the picture, if you can, and turn the brightness down to where you just see the sparks of "snow." You may need to adjust it a bit.
Anywhere from one to ten percent of the faint flashes of light on the screen are thought to be from the CMBR. It's not much of a picture, but it is a ghost of the creation of the Universe!
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