"According to new research, gravity may have been able to create light."
https://www.popularmechanics.com/space/deep-space/a43567763/gravity-can-create-light/
"Gravity can turn itself into light, but only if space-time behaves in just the right way, a research team has found.
Under normal circumstances, you cannot get something from nothing. Specifically, the Standard Model of particle physics, the reigning theory that explains the subatomic zoo of particles, usually forbids the transformation of massless particles into massive ones. While particles in the Standard Model constantly change into each other through various reactions and processes, the photon — the massless carrier of light — cannot normally change into other particles. But if the conditions are just right, it is possible — for example, when a photon interacts with a heavy atom, it can spontaneously split off to become an electron and a positron, both of which are massive particles."
https://www.livescience.com/physics-mathematics/particle-physics/astronomers-found-a-way-for-gravity-to-create-light-new-study-suggests
"Researchers have discovered that in the exotic conditions of the early universe, waves of gravity may have shaken space-time so hard that they spontaneously created radiation."
https://phys.org/news/2023-04-physicists-gravity.html