Cosmic Microwave Background: The Afterglow of the Big Bang
If you could somehow rewind the universe all the way back to its earliest moments, everything would be unimaginably hot, dense, and bright. There were no stars, no galaxies, and no planets yet. Just a rapidly expanding sea of energy and particles.
But even though that early universe is long gone, it left behind something we can still detect today: a faint glow that fills the entire sky.
