Cosmic background radiation

Continuing the theme of psalms influenced by Babylon, on Mondays in Week 2 at the Office of Readings we have Psalm 19. Again, the first half was probably adapted from a Babylonian hymn to the sun: God has "set a tabernacle for the sun, that comes forth as a bridegroom out of his chamber and rejoices as a champion to run his course." (Psalm 19:5; Common Worship).

But more whimsically, I like to think of verses 2-4 as describing cosmic background radiation (CBR): "One day pours out its song to another and one night unfolds knowledge to another. They have neither speech nor language and their voices are not heard, yet their sound has gone out into all lands and their words to the ends of the world." (Psalm 19:2-4; Common Worship).

CBR is thermal radiation that fills the universe, at a temperature less than 3K (-270 °C). It can be picked up by sensitive radio telescopes, and which show that it is almost uniform in all directions. Any proposed model of the universe, such as the Big Bang, must explain this radiation and its uniformity. Many years ago, the problem was taught to me in terms of the event horizon: how did parts of the universe outside the event horizon of other parts of the universe, i.e. with no possible causal link, happen to be at the same temperature? And so a magic wand was waved (so it seemed to me at the time), and cosmic inflation was added to the Big Bang model. Inflation is "the theorized extremely rapid exponential expansion of the early universe by a factor of at least 10⁷⁸ in volume... As a direct consequence of this expansion, all of the observable universe originated in a small causally connected region."

And so "their sound has gone out into all lands and their words to the ends of the world". And no, nowadays I haven't a clue about what most of the two linked Wikipedia articles are about!