The universe had a clandestine life before the Big Bang, new study indicates

The secrets of dark matter and black holes could lie before the Big Bang, a recent study of “bouncing” cosmology hints.

The Big Bang may not have been the commencement of the universe, according to a new theory of cosmology that proposes the universe can “bounce” between phases of contraction and expansion. If that theory is in fact true, then it could have profound consequences about the nature of the universe, including two of its most enigmatic components: dark matter black and holes.

With this in mind, a brand new study proposes that dark matter could be composed of black holes formed during a transition from the cosmos’s last contraction to the present expansion phase, which occurred prior to the Big Bang. If this proposition holds, the gravitational waves generated in the course of the black hole formation process might be detectable by future gravitational wave observatories, offering a way to confirm this dark matter generation scenario.

Observations of stellar movements in galaxies and the cosmic microwave background (CMB) — an afterglow of the Big Bang — show that about 80% of all matter in the cosmos is dark matter, a material that doesn’t reflect, absorb or emit light. Despite its abundance, researchers are yet to identify what dark matter is made of.

In the new study, scientists explored a scenario where dark matter comprises of primordial black holes formed from density variations that occurred during the cosmos’s last contraction phase, not long before the period of expansion that we observe today. They published their conclusions in June in the Journal of Cosmology and Astroparticle Physics.

The bouncing cosmos

The traditional cosmological understanding of the cosmos suggests that it started from a singularity, followed by a short period of tremendously rapid expansion, termed inflation. But, the authors behind the new study analysed a far more interesting theory, known as non-singular matter bouncing cosmology, which postulates that the cosmos first endured a contraction phase. This phase concluded with a rebound due to the increasing density of matter, leading to the Big Bang and the accelerated expansion we observe now.

In this bouncing cosmology, the cosmos contracted to a size approximately 50 orders of magnitude smaller than it is now. Post the rebound, photons and other particles were born, marking the Big Bang. The matter density was so high near the rebound that small black holes formed from quantum fluctuations in the matter’s density, making them feasible candidates for dark matter.