Dark matter easily represents one of the most mysterious terms in astrophysics. Despite being far more prevalent throughout the Universe than the regular matter that we’re all interacting with daily, dark matter cannot be directly detected in any way. But scientists know it’s there due to an extra amount of mass that composes the Universe.
Dark matter is also the culprit for the unexplained motion of stars within galaxies, and science sure has a lot to uncover about this aspect. Thanks to a new theory described in the journal The Physical Review Letters, scientists are proposing the idea that cosmic bubbles from the early Universe could have led to the current abundance of dark matter.
There’s still a lot more to learn
The new study co-author Andrew Long, who is an assistant professor of physics at Rice University in Houston, admits the obvious by declaring:
Although we know how much dark matter our Universe contains, for decades now, we’ve been left wondering about dark matter’s nature and origin,
He also proposes a new perspective over the dark matter enigma:
Is dark matter a collection of elementary particles? If so, what are the properties of these particles, such as their mass and spin? What forces do these particles exert and what interactions do they experience? When was the dark matter created, and what interactions played an important role in its formation?
Andrew Long together with other physicists known as Michael Baker (the University of Melbourne in Australia) and Joachim Kopp (the Johannes Gutenberg University of Mainz in Germany), wanted to find out when and how did dark matter formed itself. They looked at a fraction of a nanosecond after the Big Bang when particles collided and annihilated each other instantly. The scientists believe that besides all of the elementary particles known today, there’s enough evidence that there were other particles around during the early Universe, such as dark matter.
Eyes set on thermal relics
Scientists also suspect that those hypothetical particles could also be around today in the form of thermal relics. The main assumption is that in the fractions of a second after the Big Bang, the plasma underwent a phase transition in a similar way to what happens now when matter moves from one state to another. In this case, bubbles of cooled plasma formed during the early Universe. The bubbles further expanded and merged until the entire Universe went towards a new phase.
Andrew Long comes to clarify things once more by stating:
As these droplets expanded throughout the Universe, they acted like filters that sifted dark matter particles out of the plasma,
He also added:
In this way, the amount of dark matter that we measure in the Universe today is a direct result of this filtration in the first fractions of a second after the Big Bang.
One of the candidates for dark matter is represented by WIMPs (Weakly Interacting Massive Particles,). These particles would interact with matter only via gravity and the weak nuclear force, which are two of the fundamental forces of nature. However, there must be said that WIMPs are only hypothetical particles, meaning that their existence has to be proven first.
Dark matter is far more prevalent throughout the Universe than normal matter. While the latter is distributed in about 5%, dark matter exists for about 27% of the mass of the observable Universe. Dark energy is another major component of our physical reality, as it’s in charge of the accelerated expansion of the Universe itself. Dark energy is even more prevalent than both normal matter and dark matter combined.