Some new 'echoes' in space suggest the universe didn't start with a Big Bang, but more of a Big Bounce.
arXiv · March 17, 2026 · 2603.13924
The Takeaway
Standard cosmology says everything began in a single explosion, but new patterns in ancient ripples of space-time suggest a previous universe actually collapsed and then 'bounced' back out. This would mean our universe has a history that stretches back before the Big Bang.
From the abstract
We report a novel feature of relic gravitational waves (GWs) in non-singular bounce cosmologies that is testable in light of GWs astronomy. In non-singular bounce cosmologies, the effective potential $M_p^2 a^{\prime \prime}/a$ that governs the evolution of primordial GWs contains two peaks due to the existence of contraction phase prior to the standard expansion phase. Accordingly, relic GWs interference between the two peaks, resulting in a distinctive oscillatory feature in the spectrum, anal