PhysicsUnexpected epochs of stillness that punctuate the cosmic timeline could offer a natural explanation for dark matter and many other unsolved astronomical mysteries 10 February 2025 NASAAsk someone how the universe began and they will probably reply with those three familiar words: the big bang. But as recently as the 1960s, cosmologists hotly debated this matter. On the other side of the argument to the big bang was the idea of an unchanging steady state universe, the density of which was kept the same by continually adding new matter as it expanded.In the end, observations ruled out the idea of a steady state universe and cemented the place of the big bang in the canon of cosmology. That primordial explosion started a process of continual expansion, and today cosmologists view the universe as a place of constant flux.But now a bold group of cosmologists is questioning all that. To be clear, this isnt a return to the steady state universe, but something altogether more intriguing. The researchers are proposing that the universes history may have been punctuated by spells of eerie stillness. These periods of cosmic stasis could arise in such a way that they replace whole epochs of conventional cosmic history or become spliced within that timeline.Bold is certainly the word for this hypothesis. Its pointing to a whole different family of possibilities that before this we didnt realise could happen, says Adrienne Erickcek at the University of North Carolina at Chapel Hill, who wasnt involved in the work. But if these static periods do exist, they could solve all manner of conundrums, including what dark matter is made of. Even more exciting, these ideas may soon be testable.