'Gravity Portals' Could Morph Dark Matter Into Ordinary Matter (livescience.com) 49
fahrbot-bot shares a report from Live Science: Astrophysicists have an idea that could help to solve two mysteries: the reason for the bizarre abundance of super-high-energy radiation shooting from the center of our galaxy and the identity of invisible stuff called dark matter that has perplexed the world since its discovery some 50 years ago. And the idea has a super-cool name: gravity portals. The idea goes, when two dark matter particles (whatever they are) get sucked into one of these portals, they obliterate each other and spit out shockingly strong gamma rays. This line of thinking can potentially explain why the galactic center -- where dense clusters of dark matter are thought to lurk -- is full of gamma rays; and it could shed light on how the dark matter behaves and might occasionally interact with the normal matter of our universe. The study has been published to arXiv, but has yet to be peer-reviewed.
Occam's Razor (Score:3)
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Wacko Theory "A" has 3000 parts and Wacko Theory "B" has only 2000, so 2000 wins? Maybe God is Rube Goldberg.
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More Accurate Picture (Score:5, Informative)
Wacko Theory "A" has 3000 parts and Wacko Theory "B" has only 2000, so 2000 wins?
That's not at all the picture here though. What they are trying to explain is an observed excess of electrons and positrons from the galactic core.
Wacko Theory "A" is to invent an entirely new interaction related to gravity between hypothetical particles that we still have not yet detected to explain it. "Wacko" Theory B is to slightly adjust the models we have for Supernovae which are based on physics we already understand and know well, operating under conditions that are less well understood, to produce more electrons and positrons from decay of nuclei produced during the blast.
Now, which of those theories sounds more plausible? The one based on inventing entirely new physics we have no evidence for or the one based on physics we understand well operating under conditions we don't have very good knowledge of?
If that is not convincing then be aware that this is far from the only new physics model that has been invented to explain this excess. The paper itself refers to earlier models based on hidden dark sectors that weakly couple to the Standard Model particles. While this new theory is possible there is no reason to believe it over the other new-physics theories and there may be a way to explain the excess without any new physics at all.
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Now, which of those theories sounds more plausible? The one based on inventing entirely new physics we have no evidence for or the one based on physics we understand well operating under conditions we don't have very good knowledge of?
Just modify the epicycles a little more. I'm sure we'll figure it out. No need to think of anything new.
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Epicycles were actually underrated. They could model the movement of the planets quite accurately with enough layers of circles. It's a kind of "circular regression". Their real problem was that nobody could explain the mechanism behind the hypothetical circles, or detect the circles themselves. It kind of reminds of how String Theory throws in yet more dimensions to "explain" kinks in the theory. 12 dimensions? That sounds silly.
If epicycles are circular regression, then string theory is dimension regressi
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Bad science, good mechanism theory (Score:2)
As you point out, the epicycles are a type of function expansion of the planetary motions.
Did they just give a good approximation to speed and direction across the celestial sphere, or did they also give a reasonable approximation to radial distance (from the Earth).
I remember doing this in high school physics class, or maybe it was some outside-of-class activity I had signed up for. We reproduced Kepler's mapping of the heliocentric orbit around the Sun.
I don't remember the details and underlying a
Do you believe in the Saskwatch? (Score:2)
Just modify the epicycles a little more. I'm sure we'll figure it out. No need to think of anything new.
If you see a tree fall over at a distance in a forest on a calm day is the first explanation that leaps to mind that a mythical Saskwatch knocked it over or that it was likely either a beaver or a human with an axe? All are theoretical possibilities but I would argue that one seems a lot less plausible than the others based on the available data.
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I agree with you, maybe a sarcasm tag was eaten... On the other hand, we already know how trees falling down works.
We've been looking around the tree for beavers for decades and still haven't seen any. Time to think about other alternatives maybe?
What if you saw a tree falling up? Is it still a beaver because that's the only thing we know? Do we modify beavers to be telekinetic, or is it time to think outside the box?
Re: Occam's Razor (Score:2, Insightful)
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It may be that we don't understand how to measure long distances in space (once parallax no longer can work), that only requires 2 parts of currently theory to need adjustments.
Far distances are based on red shift(greater red shift == greater distance) and standard candles. Red shift assumes we understand all possible causes of the red shift of light. If we are missing on detail then red shift is giving us the wrong data and the distances and sizes of everything drops, and the expansion rates drop, and da
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If we are missing on detail then red shift is giving us the wrong data and the distances and sizes of everything drops, and the expansion rates drop, and dark matter should no longer be needed.
No. If we are missing details then distances will probably be different from what we currently calculate. Smaller? Maybe? Larger? Also maybe. Affect on the need for Dark matter could be needing more, less or not at all.
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It is overestimating the distances that would make a lot if the issues the extras are solving.
If we overestimate the distance, then the galaxies are really smaller than we think and so mass is actually spread out less than we expect and the velocities the galaxies are rotating at are slower.
Overestimating the distance also causes the need for the "expansion of the universe" that is more weirdness that makes little or no sense, and seems to have been accepted as the truth (because it was measured) without an
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Occam's razor says we don't understand gravity. Doesn't mean there are no WIMPs, just that it is the more likely solution.
Not really. Both changing the model of gravity and adding new Dark Matter particles are, on the face of it, both adding new interactions and particles beyond those we already know so from that point neither seems more likely. What seems to break the tie though is the evidence from colliding galaxies which suggest that while the ordinary matter in each interacts and slows down the Dark Matter does not and carries on. This leads to the gravitational field (measured by how it bends light) being in a different
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What do we really know of the rotation of galaxies if our understanding of the transport of light is in error? We are using extremely fine differences in red shifts for this. So maybe dark matter aint all its cracked up to be, and we definitely dont have our understanding of radiation down pat.
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FYI, for those confused about correct usage of semicolons (in which case, you really should not be here), this is not it.
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Cosmic rays have particles that could be results of that.
Some quantum features of gravity are expected too.
Thus why not to try such a way, at least to see if it could work at all.
No they could not (Score:2)
If it hasn't been peer-reviewed... (Score:2, Insightful)
It's not ready for public consumption. Have some standards.
Re: If it hasn't been peer-reviewed... (Score:2)
Re: If it hasn't been peer-reviewed... (Score:1)
Star Trek does better science than this. They should watch a few episodes before writing their next paper and upping out more grant requests.
The true god particle (Score:1)
The great thing about dark matter is that it can solve every problem, fills every gap in our understanding.
Re: The true god particle (Score:2)
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Are we really conscious tho? Heard about the idea of "philosophical zombies"?
Re: The true god particle (Score:1)
I think, therefore I am.
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In your specific case, you can lean on Descartes and safely assume that you're conscious. As you're reading Slashdot, I can understand why you'd think that others were not.
The galactic centre (Score:2)
Why wouldn't a SMBH suck in dark matter as well as ordinary matter?
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Why wouldn't a SMBH suck in dark matter as well as ordinary matter?
There is every reason to think that it would.
Every observation made so far shows a gravitational interaction in both ways.
This is the reason colliding galaxies such as the bullet cluster are such a pain in the ass to explain.
Modeling what we know of gravity predicts how galaxies interact, right up until they collide, and the math then gives incorrect predictions.
If you put in a gravitationally interacting particle, then the math correctly predicts how galaxies interact, how galaxies colliding interact, and
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It does.
The article is about production of ordinary matter from DM via quantized general relativity, regardless of presence of black holes around.
Does it work in reverse? (Score:2)
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This exactly. If dark matter can interact and produce fermions & bozons then I would expect that the reverse can also happen. In which case I would have expected that it would have been seen at CERN: interactions where there is lost energy - as we would not see the dark matter. This has not been observed as far as I know.
"Dark" matter is offensive (Score:1, Troll)
Can't we call it "ordinarily-challenged matter" instead?
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Hell, I thought it was funny. Must be some snowflakes out there for whom *everything* is IdPol.
The poor quality of science writers today (Score:5, Informative)
FTA:
" the collision boosts the photon's energy so much that it begins to give off gamma rays that we can see."
Err, no, photons don't give off gamma rays or any kind of EM radiation, they ARE EM radiation.
If the journo can't get uttery basic stuff like this correct what hope is there for the rest of the article dealing with exotic physics?
As for the theory itself:
"According to the new theory, dark matter particles can occasionally annihilate each other through nothing more than chance gravitational interactions"
Given dark matter responds to gravity it should congregate at the centre of stars and other massive objects, and if that were the case it should constantly be annihilating itself and we'd see this in the energy signature of a stars output.
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Given dark matter responds to gravity it should congregate at the centre of stars and other massive objects, and if that were the case it should constantly be annihilating itself and we'd see this in the energy signature of a stars output.
Not really. If it creates electrons and positrons then these will just add to the star's energy output but the effect will be very minimal because of the low rate of annihilations. We have done searches for neutrinos from DM annihilations at the heart of the Sun which would be one way to see this effect (if it is there) since the neutrinos would make it out from the core and those from the nuclear interactions have extremely low energies.
However, if you only produce electrons and positrons then the gala
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Re: The poor quality of science writers today (Score:2)
We dont know whether it can lose energy by some other mechanism. Plus zipping in and out in a straight line is only one option - dark matter could be orbiting inside stars.
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The article is pretty badly written, and the journalist clearly doesn't know much physics but technically photons can "give off" photons. High energy photons can split, and can also scatter off other photons. Deciphering these pop sci articles is an art, but it might be the author was told something like: photons interact with high energy electrons (and presumably positrons too) pumping up the photon's energy, which then splits to produce two characteristic gamma rays.
Bummer, man (Score:2)
I bet you worked up a hunger to eat some of that pizza and then Bam!, it vanished?