Scientists finally find out how much dark matter (the almost imperceptible material that is said to throw it all away but doesn’t emit light) actually weighs.
The new estimate helps pinpoint the weight their particles could carry, with implications for what mysterious things actually are.
The research drastically reduces the potential mass of dark matter particles, between an estimated 10 ^ minus 24 electronvolts (eV) and 10 ^ 19 Gigaelectron volts (GeV), to between 10 ^ minus 3 eV and 10 ^ 7eV – a possible range of accumulates many trillions of trillions times smaller than before.
The findings could help dark matter hunters focus their efforts on the indicated range of particle masses, or they could reveal that there is a hitherto unknown force in the universe, said Xavier Calmet, a professor of physics and astronomy at the University of Sussex in the United Kingdom.
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Calmet, along with PhD student Folkert Kuipers, also from the University of Sussex, described their efforts in a new study to be published in the March issue of Physical letters B.
What is dark matter?
According to some estimates, dark matter accounts for approximately 83% of all matter in the universe. It is believed to interact only with light and ordinary matter through gravity, which means it can only be seen by the way light rays curve.
Astronomers found the first signs of dark matter when contemplating a galactic cluster in the 1930s, and theories about galaxies were surrounded by large halos of dark matter and became currents from the 1970s, when astronomers realized that galaxies were spinning faster than they should. , given the amount of visible matter they contained.
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Possible candidates for dark matter particles include tiny, phantom particles known as neutrinos, theoretical dark and cold particles known as axions, and the proposed weakly interacting massive particles or WIMP.
The new massive limits could help eliminate some of those candidates, depending on the details of the specific dark matter model, Calmet said.
Quantum gravity
What scientists do know is that dark matter appears to interact with light and normal matter only through gravity, and not through any of the other fundamental forces; so the researchers used gravitational theories to reach their estimated range for the masses of dark matter particles.
It is important to note that they used concepts from quantum gravity theories, which resulted in a much narrower range than previous estimates, which only used Einstein’s theory of general relativity.
“Our idea was very simple,” Calmet told Live Science in an email. “It’s amazing that people haven’t thought about it before.”
Einstein’s theory of general relativity is based on classical physics; it perfectly predicts how gravity works most of the time, but decomposes in extreme circumstances where quantum mechanical effects become significant, such as in the center of a black hole.
Theories of quantum gravity, on the other hand, attempt to explain gravity by quantum mechanics, which can already describe the other three known fundamental forces: the electromagnetic force, the strong force that holds more matter together, and the weak force it causes. radioactive decay.
However, none of the theories of quantum gravity yet have solid evidence to support them.
Calmet and Kuipers estimated the lower limit of the mass of a dark matter particle using general relativity values and estimated the upper limit of the life of dark matter particles predicted by quantum gravity theories.
Calmet said that the nature of general relativity values also defined the nature of the upper limit, so they were able to derive an independent prediction from any particular model of quantum gravity.
The study found that while quantum gravitational effects were almost negligible, they became important when a hypothetical particle of dark matter took a long time to decay and when the universe was as old as it is now (approximately 13.8 billion years). ), he said. .
Physicists previously estimated that dark matter particles should be lighter than the “Planck mass” (approximately 1.2 x 10 ^ 19 GeV, at least 1,000 times heavier than the largest known particles), but heavier. of 10 ^ minus 24 eV to accommodate observations of smaller galaxies known to contain dark matter, he said.
But so far, few studies had attempted to reduce the range, although much progress had been made in understanding quantum gravity over the past 30 years, he said. “People just didn’t look at the effects of quantum gravity on dark matter before.”
Strength unknown
Calmet said the new limits for dark matter particle masses could also be used to test whether gravity only interacts with dark matter, which is widely assumed, or if dark matter is influenced by an unknown force of the nature.
“If we found a particle of dark matter with a mass out of reach that we were discussing in our paper, we would not only have discovered dark matter, but also very strong evidence that … there is some new force beyond gravity that it acts on dark matter, ”he said.
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This article was originally published by Live Science. Read the original article here.