In 2023, physicists discovered nearly imperceptible ripples in spacetime, linked to pulsar timing arrays. Initially, these low-frequency gravitational waves were thought to result from a phase transition shortly after the Big Bang. However, new research challenges this theory. Andrew Fowlie from Xi’an Jiaotong-Liverpool University highlighted issues with this explanation. Phase transitions, like water freezing, involve sudden changes in a substance’s properties at critical temperatures, but supercool transitions can delay these changes.