Darkness and Light: The Universe could have started with a “dark” Big Bang

A scientific team of American and Swedish cosmologists put forward an exotic hypothesis that perhaps there could be more than one Big Bang. 

Using theoretical calculations and simulations, they found that before the inflationary expansion of the Universe and nucleosynthesis, which led to the appearance of all elementary particles known to us, there could be at least one more similar event. However, it released dark matter and filled our Universe with it. Their calculations and conclusions are published on the arxiv website.

In the standard cosmological picture, the early universe was a very exotic place. Perhaps one of the most significant events that has happened in the Metagalaxy, or simply put in our Universe, is the cosmological inflation which, very early on afterward, led our Universe into a period of extremely rapid expansion. When it ended, the exotic quantum fields that led to this event disintegrated into a stream of particles and radiation that still exist today.

However, despite the success of this concept, we are still extremely far from fully understanding the structure of our world. One of the main secrets of cosmology is dark matter, which is almost impossible to register and it is not known what it consists of, but it occupies a dominant position in the structure of the Universe. The standard assumption in big bang models is that whatever process produced particles and radiation also produced dark matter. And after that, dark matter just hung around, ignoring everything else.

According to the new concept, everything can be much more interesting than it seems at first glance, and dark matter could develop along a completely separate trajectory. In this scenario, when the so-called Big Bang, or dramatic expansion of space-time ended, the “Dark Bang” could still infuse some kind of exotic quantum field. As the Universe expanded and cooled, this additional quantum field eventually transformed, which could lead to the formation of dark matter.

From the point of view of an earthly layman, the new hypothesis sounds pretty crazy, but reality is often more fantastic than any fiction, and this approach has its advantages. It lies in the fact that it allows you to separate the evolution of dark matter from normal, “light” matter, so that Big Bang nucleosynthesis can proceed as humanity currently understands it, while dark matter develops along a separate path. 

Roughly speaking, the world can be divided into light and darkness. This unorthodox and dual approach opens up new possibilities for studying a rich variety of theoretical models of dark matter, because when it has a separate evolutionary path, it is easier to track it in calculations to see how it compares to observations. Thus, the team of authors of the article was able to determine that if there was a “Dark Explosion”, then it should have occurred when the Universe was about one month old.

The study also showed that dark inflation could have given rise to a unique signature of strong gravitational waves that persist in the modern universe. Ongoing experiments, such as pulsar synchronization, should be able to detect these gravitational waves.