After the Big Bang, a faint glow remained, like a quiet voice coming from the very beginning of time. Scientists long listened to this hum, trying to discern hidden rhythms. And then, with a computer program that finds patterns in data on its own, they heard something unexpected. The rhythm seemed reversed, as if a vinyl record were played backwards.

Such “reversed” waves could point to a very brief and unusual period in the infant universe’s life — something like a super-fast inflation right after birth. If confirmed, we’ll get an important clue about the nature of the very first moments, which still remain a mystery.

Even Georges Lemaître suggested the universe expands, and Ralph Alpher predicted that after the Big Bang, such a glow should remain. Today, thanks to precise measurements of the spectrum of this radiation, we can peer into that distant epoch.