If the beginning of the universe is still a mystery to cosmologists, the end is even more complicated to know, but theoretical physics tries to venture into playing with scenarios that physics could allow, and a group of researchers now believe that dark energy could lead to a second Big Bang.
Dark Energy, the Cause of Chaos
According to the standard model of cosmology, all the matter in galaxies, planets, stars, and every visible object composed of baryonic matter, represents only 5% of the entire composition of the cosmos. The rest is made up of 25% dark matter and an impressive 70% dark energy. But what is dark energy, and why is it so abundant in the universe?
The standard model also explains that the universe is currently subject to constant acceleration and expansion, thanks to the pressure exerted by dark energy. Therefore, this would be the cornerstone to explain the expansive behavior of the cosmos.
Although there is a limitation to finally discovering the truth about dark energy, and it is that the cosmological constant that would describe the incidence of dark energy in the universe has not been able to be measured directly until now. That is why some believe that expansion does not behave constantly but rather works like a periodic ‘on’ and ‘off,’ which sometimes promotes the expansion of the cosmos and, in others, reduces it until another Big Bang occurs.
The phase that our universe would currently be going through would be expansive. Right now, although we may not be aware, we are expanding along with the cosmos. And although it seems like a terrifying scenario that will continue into infinity and the oblivion of all the matter contained in the universe, some cosmologists believe that it would not be the first or last time it happens.
Big Bang, Cosmic Inflation, and Universal Expansion
In the first moment after the Big Bang, the conditions were so chaotic that it is believed that a singularity was experienced. That is, both gravity and energy were so dense that current physics cannot explain the events that occurred there, a point of infinite density where our mathematical models simply fail. After this came a period of inflation, where the universe expanded. Both events, cosmic inflation at the Big Bang and the current expansion of the universe sound similar, and astrophysicists have wondered for decades whether they are actually part of the same thing.
This is where Molly Burkman and Marco Bruni, theoretical physicists, and cosmologists at the University of Portsmouth, come into action to create a model where dark energy has always played an important role. Previous research had already modeled the ‘on’ switch of dark energy at key moments to drive cosmic expansion, although no exact conclusion has been reached so far.
Burkman and Bruni wanted to go much further back to see if dark energy could have been a key piece after the Big Bang. They wondered if the mysterious energy could have prevented the singularity, as well as driving inflation and accelerating the late Universe. According to their model, dark energy not only had to have experienced an ‘on’ switch but also had to have had an infinite series of repeated ‘big bounces’ to bring the Universe to a certain size and then force it to contract to start the cycle again.
They found a crucial difference with previous models, according to the cosmologists, for dark energy to explain the Big Bang, cosmic inflation, and current expansion, matter, and radiation should not have been present in the early Universe, or else they would have disrupted inflation.
According to the model, matter and radiation had to have appeared just after inflation as a consequence of the decay of a certain portion of dark energy that eventually flooded the Universe with light and baryonic matter that we currently know.
Although it is ongoing research, it’s heading towards a promising path that could open new ways to understand how the cosmos ended up being filled with the mysterious energy that we still do not fully comprehend and how it, in turn, would explain cosmic inflation and universal expansion.
Story originally published in Spanish in Ecoosfera.