Standard theory paints the birth of the Universe as an explosion from a point of infinite density. But there is an alternative: first, the cosmos squeezed down to tiny dimensions, and then began to expand — it bounced back, like a spring. This double process left a trace in gravitational waves — ripples in spacetime that still cruise through the cosmos.

Just as two echoes from different walls merge into a shimmering sound, the waves from contraction and expansion overlapped, producing a clear rhythmic pattern. At high frequencies, it looks like an alternation of spikes and dips, unlike the chaotic noise expected from a standard Big Bang.

If Earth-based detectors catch this pulsation, it will confirm that the expansion of the Universe began not from a singularity, but from a bounce. Astonishingly, the signal strength is sufficient to be noticed by already existing observatories. Perhaps we will hear the bounce echo in the coming years.