The very first light.
Somebody mentioned this to me at the Victorian Skeptics forum the other night.
The book of Genesis, as most of us know, says something to the effect of: “When God began to create heaven and earth, and the earth then was welter and waste and darkness over the deep and God’s breath hovering over the waters, God said, ‘Let there be light.’ and there was light”, and then later on there’s a bit about the creation of the “dry land and seas and plants and trees which grew fruit with seed; the sun, moon and stars in the firmament.”
Well, the seemingly obvious question was posed to me, how could there be light in the Cosmos, before the formation of the stars?
Perhaps that’s what we know as the cosmic microwave background radiation?