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Arthur T Knackerbracket has found the following story:
The field of astronomy has been revolutionized, thanks to the first-ever detection of gravitational waves (GWs). Since the initial detection was made in February of 2016 by scientists at the Laser Interferometer Gravitational-wave Observatory (LIGO), multiple gravitational events have been detected. These have provided insight into a phenomenon that was predicted over a century ago by Albert Einstein.
As it turns out, the infrastructure that is used to detect GWs could also crack another astronomical mystery: dark matter. According to a new study by a team of Japanese researchers, laser interferometers could be used to look for weakly interacting massive particles (WIMPs), a major candidate particle in the hunt for dark matter.
To recap, WIMPS are a theoretical elementary particle that interacts with normal matter (baryonic) only through the "weak" force gravity. As with other elementary particles that are part of the Standard Model (of which WIMPS are not), they would have been created during the early universe when the cosmos was extremely hot.
WIMPs are essentially the microscopic candidate particle, which puts them at the opposite end of the spectrum from the other major candidate—the macroscopic massive compact halo objects (MACHOs). So far, multiple experiments have been conducted to find these particles, ranging from particle collisions and indirect detections to more direct methods, but the results have been largely inconclusive.
As Dr. Satoshi Tsuchida, a professor of physics at Osaka City University and the lead author of the study, told Universe Today via email:
"[Most] MACHOs are believed to consist of baryonic matter, but baryons account for only 5 percent of the universe. Thus, we cannot explain the structure of the present universe if all of dark matter consists of MACHOs. On the other hand, WIMPs are non-baryonic matter, and we have no reason to exclude [them] from dark matter… Therefore, WIMPs can be promising dark matter candidates."
(Score: 2) by Rupert Pupnick on Saturday September 14 2019, @05:37PM (3 children)
"WIMPs are essentially the microscopic candidate particle, which puts them at the opposite end of the spectrum from the other major candidate—the macroscopic massive compact halo objects (MACHOs)."
If they're macroscopic and massive, why are they so hard to find? The word "macroscopic" carries with it the implication of not needing special equipment to detect it, right? Or is there some parallel definition of "macroscopic" in particle physics of which I'm ignorant? If so, could we call it something else besides "macroscopic"?
(Score: 1, Interesting) by Anonymous Coward on Sunday September 15 2019, @04:37AM
Because they are dark and isolated. Basically, it is any baryonic matter that does not emit radiation nor interact with local objects that do. An example of a MACHO would be a comet that has been thrown into interstellar space or a black hole. You can only really "see" them through their gravitational effects on things we can see. They definitely exist, the question is how much of it exists because they are so hard to see. Other indications, like the CMB, suggests its not more than a small percentage of the total mass/energy of the Universe, but the exact amount is an open question.
(Score: 1, Interesting) by Anonymous Coward on Sunday September 15 2019, @05:01AM
https://en.wikipedia.org/wiki/Massive_compact_halo_object [wikipedia.org]
MACHO = I guess there are so many black holes, brown dwarfs, rogue planets, interstellar rocks, etc. that we didn't account for, that dark matter isn't real after all! It was just "missing matter"!
The idea is that instead of 5% ordinary matter and 27% dark matter, it's 32% ordinary matter. It has been largely ruled out as an explanation.
(Score: 0) by Anonymous Coward on Sunday September 15 2019, @08:12PM
BZZT! Wrong. It's right in the the name! Obviously, you need a macroscope to see that stuff. Sheesh!
The problem is that there is no such thing as a macroscope, hence the problem in detection. Duh!