We may not know what dark matter is, but scientists now have a better idea of what to look out for.
Based on quantum gravity, physicists have worked out new, much stricter upper and lower limits for the mass of dark matter particles. And they have found that the mass range is much smaller than previously thought.
This means that the dark matter candidates that are extremely light or heavy are unlikely to be the answer, based on our current understanding of the universe.
“This is the first time anyone has thought of using what we know about quantum gravity as a way to calculate the mass range for dark matter. We were surprised to realize that no one had done it before, just like the fellow scientists. who assessed the review.our paper, ‘said physicist and astronomer Xavier Calmet of the University of Sussex in the UK.
“What we’ve done shows that dark matter cannot be ‘ultralight’ or ‘supermassive’, as some theorize – unless it has an as yet unknown additional force acting on it. This piece of research helps physicists in two ways: it focuses the search area. for dark matter, and it may also help reveal whether or not there is some mysterious unknown extra force in the universe. ”
Dark matter is undeniably one of the greatest mysteries of the universe as we know it. It is the name we give to a mysterious mass responsible for gravitational effects that cannot be explained by the things that we can detect in other ways – normal matter such as stars, dust and galaxies.
For example, galaxies rotate much faster than they should if they are only gravity influenced by the normal matter within them; gravitational lenses – the bending of spacetime around massive objects – is much stronger than it should be. Whatever causes this extra gravity, we cannot detect directly.
We only know it by the gravitational effect it has on other objects. Based on this effect, we know there is a lot of it. About 80 percent of all matter in the universe is dark matter. It is called dark matter because it is dark. And also mysterious.
However, we know that dark matter interacts with gravity, so Calmet and his colleague, physicist and astronomer Folkert Kuipers of the University of Sussex, turned to the qualities of quantum gravity to try to estimate the mass range of a hypothetical dark matter particle. (whatever it may be).
Quantum gravity, they explain, imposes a number of limits on the existence of dark matter particles of different masses. While we don’t have a decent working theory that unites the general theory of relativity of the space-bending description of gravity with the discrete chunk of quantum physics, we know that any fusion of the two reflects certain foundational principles of both. As such, dark matter particles should adhere to quantum gravity rules about how particles break down or interact.
By carefully considering all of these boundaries, they were able to rule out ranges of mass that, according to our current understanding of physics, are unlikely to exist.
Based on the assumption that only gravity can interact with dark matter, they determined that the mass of the particle is between 10-3 electronvolts and 107 electron voltage, depending on the spins of the particles, and the nature of dark matter interactions.
That is insanely smaller than the 10-24 electronvolt to 1019 traditionally attributed gigaelectronvolt range, the researchers said. And that’s important, because it largely rules out some candidates, such as WIMPs (weakly interacting massive particles).
If such candidates later turn out to be the culprit behind the mystery of dark matter, according to Calmet and Kuipers, it would mean that they are influenced by some force unknown to us.
That would be really cool, because it would point to new physics – a new tool for analyzing and understanding our universe.
Above all, the team’s limitations provide a new framework to consider when searching for dark matter, helping to determine where and how to look.
“As a PhD student, it is great to be able to work on such exciting and impactful research,” says Kuipers. “Our findings are very good news for experimentalists as it will help them get closer to discovering the true nature of dark matter.”
The research is published in Physics Letters B.