Some black holes are remnants from the Big Bang. Usually they fade via a slow radiation leak — predicted by Stephen Hawking. But a quantum switch could invert them into white holes, explosively releasing all energy like popcorn kernels that suddenly pop.

A new study calculates this switch’s likelihood, factoring in the warping of space and cosmic expansion. The pop rate peaks only when a black hole’s lifetime matches the universe’s age — exactly timed, like popcorn in hot oil. Astronomers tested whether these pops cause mysterious fast radio bursts — brief, intense blips from deep space. Match? Barely: only in a sliver of cases, with very light black holes or those vanishing before the flip.

So the cosmic popper rarely delivers. Observations from gravitational waves to gamma rays dismiss white holes as the prime burst culprit. Yet here’s the twist: a black hole primed to pop would be tinier than an atom but as heavy as a mountain. The takeaway? It sharpens the hunt for these improbable cosmic flashes.