Dark Matter Formed When Fast Particles Slowed Down and Got Heavy, New Theory Says (phys.org) 36
Dartmouth researchers propose that dark matter originated from massless, light-like particles in the early universe that rapidly condensed into massive particles through a spin-based interaction. Phys.Org reports: [T]he study authors write that their theory is distinct because it can be tested using existing observational data. The extremely low-energy particles they suggest make up dark matter would have a unique signature on the cosmic microwave background, or CMB, the leftover radiation from the Big Bang that fills all of the universe. "Dark matter started its life as near-massless relativistic particles, almost like light," says Robert Caldwell, a professor of physics and astronomy and the paper's senior author. "That's totally antithetical to what dark matter is thought to be -- it is cold lumps that give galaxies their mass," Caldwell says. "Our theory tries to explain how it went from being light to being lumps."
Hot, fast-moving particles dominated the cosmos after the burst of energy known as the Big Bang that scientists believe triggered the universe's expansion 13.7 billion years ago. These particles were similar to photons, the massless particles that are the basic energy, or quanta, of light. It was in this chaos that extremely large numbers of these particles bonded to each other, according to Caldwell and Guanming Liang, the study's first author and a Dartmouth senior. They theorize that these massless particles were pulled together by the opposing directions of their spin, like the attraction between the north and south poles of magnets. As the particles cooled, Caldwell and Liang say, an imbalance in the particles' spins caused their energy to plummet, like steam rapidly cooling into water. The outcome was the cold, heavy particles that scientists think constitute dark matter. The findings have been published in the journal Physical Review Letters.
Hot, fast-moving particles dominated the cosmos after the burst of energy known as the Big Bang that scientists believe triggered the universe's expansion 13.7 billion years ago. These particles were similar to photons, the massless particles that are the basic energy, or quanta, of light. It was in this chaos that extremely large numbers of these particles bonded to each other, according to Caldwell and Guanming Liang, the study's first author and a Dartmouth senior. They theorize that these massless particles were pulled together by the opposing directions of their spin, like the attraction between the north and south poles of magnets. As the particles cooled, Caldwell and Liang say, an imbalance in the particles' spins caused their energy to plummet, like steam rapidly cooling into water. The outcome was the cold, heavy particles that scientists think constitute dark matter. The findings have been published in the journal Physical Review Letters.
Dark steam is now a thing :o (Score:3)
That's the sciencie bit out of the way
“Hypothetical dark matter is believed to exist based on observed gravitational effects that cannot be explained by visible matter.”
How about the dark matter effect being caused by the large-scale curvature of spacetime?
Re: Dark steam is now a thing :o (Score:3)
Large scale curvature of space time is the thing we observe, the question is what is causing that curvature, and âoecurvatureâ is not an explanation.
Re: (Score:2)
... slowed down and got heavy ...
So dark matter is actually doom metal?
I'm quite happy (Score:1)
with Dark Matter just being a lot more old expired stars than expected. I don't see why we need invent anything exotic.
Re:I'm quite happy (Score:5, Informative)
Microlensing surveys and other arguments (Score:3)
A lot of effort has gone into looking for those more-than-expected old, expired stars, at least in the Milky Way and nearby Magellanic Clouds. The technique is to observe vast numbers of stars and look for dimming transients indicating that one of those stars just passed in our line-of-sight with a visible star. The GAIA space-borne observatory is a central part of this.
By a lot of effort I mean the astronomers involved have done their homework and the signatures of such events indicating gravitational
Re: (Score:2)
That would be an occultation. To block the light from a source, the occulting body needs to have a larger area (on the sky) than the body being occulted. (If it were the other way around, you'd get a dimming of the occulted body, but not extinction ; did you notice the last annular solar eclipse you were exposed to? Probably not.)
When the masses involved get up to stellar masses, the likeli
Re:I'm quite happy (Score:4, Interesting)
If you're talking about white dwarfs, there aren't enough of them. There aren't enough neutron stars or black holes either, with the only possible exception being primordial black holes formed soon after the Big Bang in the massive density fluctuations, but then we have to figure out how Hawking radiation simply didn't make them evaporate long ago.
So it's either some sort of exotic particles, or gravity somehow behaves differently than Einstein posited, and the problem with the latter is that every test we fling at General Relativity confirms it at the scales where Dark Matter counts. So, as Sherlock Holmes said, "Once you have eliminated the impossible, whatever remains, however improbable, must be the truth."
We're running out of room for super-symmetry, sadly, which was by far the most elegant solution, so now it really is a hunt for other kinds of particles that could produce the same gravitational effects while otherwise not strongly interacting with ordinary matter.
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The main problem may be that most humans have an extreme prejudice based on the fact that all our senses work via the electromagnetic force. So people conclude "If I can't get it to somehow interact with the electromagnetic force it doesn't exist! QED!!!"
I personally have no problem with the possibility that dark matter particles simply never interact directly or indirectly with the electromagnetic force (other than bending space-time), and we may never be able to detect them through experiments. That would
Re: (Score:2)
The reason for the laws of physics, whatever they are, caring about the opinions of most humans on the subject of "the laws of physics" ... is ... ? What?
What does human prejudice or ideas of popularity have to do with whether this law of physics (versus that one) is an accurate description of how the universe works? Nothing.
Which will probably upset humans who believe they are, in some sense, significant. [SHRUG]
That a particle does not inte
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Okay. Is it your life's work to know about this stuff?
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Vera Rubin in the 1960ies measured the speed of stars in the outer regio
Re: I'm quite happy (Score:1)
Re: I'm quite happy (Score:2)
Itâ(TM)s known that dark matter is not baryonic matter. That is, itâ(TM)s not matter made from protons and neutrons (and electrons, which are fermions, but the point is the presence of baryons, not the lack of fermions).
We know this, for a few reasons. First, we have pretty decent models of what would happen in the early universe that predict that only about 20% of matter would be baryonic, which agrees with what we observe.
We observe galaxies forming far too early in the universe for them to be
Dark Matter so fat ... (Score:5, Funny)
When it sits around the Universe, it sits *around* the Universe. ;-)
Re: (Score:2)
I believe I have objective proof of this theory (Score:4, Insightful)
"Dark Matter Formed When Fast Particles Slowed Down and Got Heavy, New Theory Says"
I have experienced this effect directly, and have even come up with a term to describe it. I have definitely slowed down and gotten a bit heavy. I call it "aging".
Re: (Score:2)
Dark matter formed when God took a dump.... (Score:1)
Dark matter formation (Score:2, Insightful)
Dark matter formed when cosmologists needed a function that fit their mysterious observations. Dark matter will dissipate when theorists and astronomers develop better theories and perform better observations.
Re: (Score:2, Insightful)
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It's amazing how many so-called nerds hate science or don't understand it or both.
It didn't make anyone "mad" that they can't determine the difference between mass as measured by different means, it created a question that needed to be answered. So dark matter is the vague answer to that which either requires further explanation (as the subject of this article is trying to create a hypothesis for) or elimination if it can be shown there were issues with those original measurements (not the actual measuring,
Re: (Score:2)
Exactly. Eventually, we'll discover that dark matter is some non-linearity that we just don't understand yet.
Re:Dark matter formation (Score:4, Informative)
Your post reads like snark, but you're describing the scientific process. There is a gap in our knowledge, we put in a placeholder theory to fill the gap, and we're trying to refine it to an acceptable degree of agreement with observation.
It's science, not voodoo.
Re: (Score:3)
We don't put in a placeholder theory. We give it a name so we can talk about it. Then we work on theories, discarding them when they don't work.
"Dark matter" is the name. There have been a lot of "theories" to explain it, many of which have been suggested by posters in just this thread, from "burn out old stars" to the vague "nonlinearities we don't yet understand."
Twenty years ago the debate was between MACHOs (burnt out old stars, rogue planets, cold gas, black holes, etc.) and WIMPs (particles that inter
Re: (Score:2)
but you're describing the scientific process
Yes. A particularly shameful and pathetic version of the scientific process, anyhow. It is possible to progress without creating Aethers. However, that would involve admitting inadequacy and being humble. It's also possible to not ridicule and persecute anyone with the temerity to question your Aethers.
But instead we do both and bend our definition of "science" accommodate.
You see, (Score:3)
vaguoid particles collided with fuzzoid particles in the vast cosmic fog, producing Oz particles that skipped and danced down the yellow brick clusterfuck of dark bullshit, allowing barking Totoid particles to escape our universe so that the Haitian Witch couldn't eat him. As plausible as the other theories.
How this started (Score:3)
Re: How this started (Score:1)
Fast Particles Slowed Down and Got Heavy... (Score:2)
...when they got older.
Don't we all?
It's just another dark matter theory (Score:2)
Put it in the trash with the rest of them
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Put it in the trash with the rest of them
Yes, let's stop trying to advance at all. We've been wrong many times in the past, therefore we can never be right in the future.
Silly title (Score:3)
The title is silly. According to the standard model all matter formed when massless particles "got heavy and slowed down through a spin-based interaction."
The interesting thing about this particular paper seems to be the proposal of a specific type of particle that would form bound pairs similar to electron Cooper pairs in superconductors, allowing it to dissipate energy and form cold dark matter, and leave a possibly detectable signature in the CMB.