Recent research indicates that simple forms of matter from the early universe might be detectable through gravitational waves, which could also explain the nature of dark matter.
These findings offer a potential breakthrough in both the detection of gravitational waves and the identification of dark matter components.
Gravitational waves, ripples in space-time predicted by Einstein almost a century ago, were detected for the first time in 2015. A new study led by Yanou Cui, an associate professor of physics and astronomy at the University of California, Riverside, shows that very simple forms of matter could create detectable gravitational wave backgrounds soon after the Big Bang.
“This mechanism of creating detectable gravitational wave backgrounds may shed light on the puzzling gravitational wave signal recently captured by pulsar timing observatories,” Cui said. “Another exciting implication is that the very same form of matter may be identified as dark matter, the mysterious substance believed to make up most of the universe’s mass which has puzzled scientists for decades.”
The study, published in Physical Review Letters, paves the way for uncovering new fundamental physics using the biggest laboratory: the universe itself. In the following Q&A, Cui answers a few questions about the research:
What are these very simple forms of matter?
The simple form of matter is a type of ultra-light scalar field matter. Scalar means the matter has no internal rotation (spin), and it resembles the Higgs boson. These forms of matter are very light, each with mass a millionth or even a billionth the mass of an electron. Because of their very small mass, they act more like waves than particles, and they permeate the universe.
The gravitational waves need to have high enough intensity, analogous to electromagnetic waves, for current experiments to be sensitive enough to capture them. Also, they need to be in the frequency bands that these experiments are sensitive to; so far, only certain ranges of gravitational wave frequency can be detected due to technology limitations.
These simple forms of matter generate a detectable radiation background of gravitational waves shortly after the Big Bang and no other time?
Yes, the gravitational waves are generated during an era when the expansion rate of the universe is around the mass of the scalar field. It would stop beyond this point as particle production would be shut down at some point by the internal mechanism. When I say shortly after the Big Bang, it is still a fraction of second after that. Much after the Big Bang, there can be GW production from astrophysical sources such as black hole mergers, which the Laser Interferometer Gravitational-wave Observatory observed.
Why were these simple forms of matter not known until now?
They do not interact with known matter in ways other than the super-weak gravitational interaction. The gravitational wave signal we demonstrated is the way to detect them. But if they are dark matter, we have known about them from the general evidence of dark matter. Again, because they only interact with visible matter gravitationally, which is very weak, we did not know much about them before.
You say it would be exciting to identify this simple form of matter as dark matter. Is that because we will finally know what dark matter is made of?
Yes, this is one of the highlights. But also, it is highly nontrivial to produce detectable gravitational waves, and we found a simple form of matter, possibly dark matter, can produce such gravitational waves — a significant theoretical accomplishment. Also, as mentioned before, the puzzling pulsar timing finding last year can be explained by this mechanism.
Reference: “Gravitational Wave Symphony from Oscillating Spectator Scalar Fields” by Yanou Cui, Pankaj Saha and Evangelos I. Sfakianakis, 11 July 2024, Physical Review Letters.
DOI: 10.1103/PhysRevLett.133.021004
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6 Comments
Picture of presumed “gravity waves” resembles a bobbing lure floating in a very slow stream, so no surprise it’s from U C Riverside, I suppose.
It’s a little bit misleading to imply the “final parsec problem” was discovered in simulations, as some articles out there suggest, when it’s not mentioned that the simulations involve trivial recent assumptions motivated only by the recently observed GW background.
Caltech has nominated a rival to the Bullet cluster for best example of a collision aftermath helped with a non-highlighted critical lagging mass effect tail best hidden under x-ray data.
Can’t question the dubious collective dark/normal velocity differences they’re suggesting, but the frozen picture in blue and red is merely provocative, not persuasive. But of course, and once again, the DM community always knows just how bright compact cold masses should be, despite major new discoveries on the BH and NS fronts and related musings on other unappreciated interstellar compact cold masses, and please don’t call them MACHOs unless wonkiness stands there an asset.
Big Bang never happened and dark matter doesn’t exist. But it’s a good grift to milk money from the gullible government.
Lance Thomas Davidson in Bali Indonesia corrected Einstein’s equation for general relativity and it’s made a substantial impact on cosmology, physics, and quantum sciences
Fascinating and currently relevant I will have to check this out having just written that the momentum part of E=mc2 seems to get overlooked with shocking frequency by those who would claim to know better and suggest that nothing can travel faster than light (despite relativity and what we know about phenomena like entanglement).
Einstein was useful but incomplete, as are all models.
What happened before the Big Bang (in our physical universe)? Physics don’t know (and never will if they consider everything physics), so why are we still proceeding with such incorrect models rather than question deeper assumptions?