Physicists Disagree Over New Dark Matter Claim (sciencemag.org) 69
sciencehabit shared this article from Science magazine:
For decades, astrophysicists have thought some sort of invisible dark matter must pervade the galaxies and hold them together, although its nature remains a mystery. Now, three physicists claim their observations of empty patches of sky rule out one possible explanation of the strange substance — that it is made out of unusual particles called sterile neutrinos. But others argue the data show no such thing.
"I think that for most of the people in the community this is the end of the story," says study author Benjamin Safdi, an astroparticle physicist at the University of Michigan, Ann Arbor. But Kevork Abazajian, a theoretical physicist at the University of California, Irvine, says the new analysis is badly flawed. "To be honest, this is one of the worst cases of cherry picking the data that I've seen," he says. In unpublished work, another group looked at similar patches of sky and saw the very same sign of sterile neutrinos that eluded Safdi...
Alexey Boyarsky, an astroparticle theorist at Leiden University, is unconvinced. "I think this paper is wrong," he says. Boyarsky says he and his colleagues performed a similar, unpublished analysis in 2018, also using images from XMM-Newton, and did see a 3.5-keV glow from the empty sky, just expected from peering through a halo of sterile neutrinos.
"I think that for most of the people in the community this is the end of the story," says study author Benjamin Safdi, an astroparticle physicist at the University of Michigan, Ann Arbor. But Kevork Abazajian, a theoretical physicist at the University of California, Irvine, says the new analysis is badly flawed. "To be honest, this is one of the worst cases of cherry picking the data that I've seen," he says. In unpublished work, another group looked at similar patches of sky and saw the very same sign of sterile neutrinos that eluded Safdi...
Alexey Boyarsky, an astroparticle theorist at Leiden University, is unconvinced. "I think this paper is wrong," he says. Boyarsky says he and his colleagues performed a similar, unpublished analysis in 2018, also using images from XMM-Newton, and did see a 3.5-keV glow from the empty sky, just expected from peering through a halo of sterile neutrinos.
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Not a fan of modern anthropology I see. We're all from Africa. So, which boat will you be boarding?
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Not a fan of modern anthropology I see. We're all from Africa. So, which boat will you be boarding?
If we're all from Africa then there is no such thing as race so nobody can be racist. Glad we cleared that up.
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Are there a 100 quarks inside the proton or a million?
There are 3 quarks inside a proton.
Meaningless question (Score:5, Informative)
Are there a 100 quarks inside the proton or a million? Physics does not know.
No, physics says that this is an undefined quantity which is not the same as saying that it does not know. This is like claiming that physics does not know whether an electron is a wave or a particle which, while technically true is a meaningless statement because we know it is both.
There are three "valence" quarks in a proton that carry the basic quantum numbers of the bound state and an undefinable number of "sea" quarks that are essentially virtual quark-anti-quark pairs popping in and out of the vacuum which can carry some fraction of the energy and momentum of the proton. We do actually have good models of the proton's "parton distribution function" which determines the probabilistic makeup of the proton. This is enough to know that asking how many quarks are inside a proton is a meaningless question unless you refer specifically to the valence quarks.
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An electron is probably neither a wave or a particle. It just looks like these things from where we're standing.
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...but we have no idea what "an electron" is..
It's a quantum fluctuation of the electron-fermion field. We know its properties and can predict its behaviour using the second most precisely tested model that humans have ever devised. Hence, we know what an electron is more than we know what just about anything else that exists is.
"Probabilistic makeup" means only one thing - you don't know shit about it
What this statement shows is that you have no understanding of quantum mechanics. The premise of your question "what is the make-up of the proton" assumes that there is a precise make-up that can be known. However, that prem
Re:Particle physics is basically shamanism (Score:5, Insightful)
No, it isn't. Science is Science, just that and nothing else.
Scientists do not do a lot of browbeating until a major problem seems headed for the world or humans. They did complain bitterly about the U.S. being unprepared for epidemics, it turns out they were right. They are complaining about anthropomorphic global warming, they are right there too. It would be immoral to not warn ahead of time.
Re:Particle physics is basically shamanism (Score:5, Insightful)
As an example: For a christian, performing satanistic rituals is soimething you should never do, as it is a direct way to Hell. For a String theorist on the other hand, it's quite important to be able to calculate something according to Loop Quantum Gravity, so he might be able to devise an experiment that can test the different predictions of each theory.
Re:Particle physics is basically shamanism (Score:5, Insightful)
Religion tells you something for sure, and you can believe it in all eternity.
Which religion? They all seem to disagree with each other and I'd like to pick the one with the correct answers - oh, wait...
(Not arguing with you, just sayin' that believing in Religion is pretty much the same as believing in prejudicial Fairy-tales or Magic.)
Religion tells you about the Why, ...
Religion doesn't actually tell you anything, it merely offers a usually biased opinion stated as (their believers) truth/fact.
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Religion tells you about the Why, ...
Religion doesn't actually tell you anything, it merely offers a usually biased opinion stated as (their believers) truth/fact.
I was trying to hint at something else. In religions, you often find legends, why something is as it is (for instance, because $DEITY made it so). In Science, you instead find theories, and each theory can be described by what it rules out. For instance, Thermodynamics forbids the existance of a perpetuum mobile, and each of the Laws of Thermodynamics rules out a special type of perpetuum mobile. The theories of Gravity in turn (both the Newtonian one and General Relativity) rule out the ability to shield o
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Ya, I get that, thanks.
Not to belittle anyone, but I think Religion is more for people who want easy answers that one doesn't have to (or, more correctly, shouldn't) think about too much and address their hopes, while Science is for those looking for something more and willing are to do hard work to find out more, even if the answers ultimately aren't what they expect, want or hope.
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Don't mistake most religions with the Judea-Christian (and Islam is in there) ones as many can easily co-exist with science. Even Catholicism is now mostly in agreement with science, just talking about why the big bang and how it set everything in motion rather then denying it. Ones like Buddhism are more about how to live then answering wrongly how things work.
There's no reason for religion and science to conflict as they cover different domains, it's just some really aggressive religions that are broken a
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Currently, that's what the evidence is in favour of. At some point even scientists have to consider some things mostly settled until evidence says otherwise.
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and each of the Laws of Thermodynamics rules out a special type of perpetuum mobile.
No, only one does that. All the others have nothing to do with perpetuum mobiles.
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Then you have a Perpetuum mobile of second order, that does nothing else than moving energy from lower to higher temperatures, violating the Second Law of Thermodynamics, And there is the Perpetuum mobile of the third order, which, once started, moves on forever without getting energy or emitting energy, violating the Third Law of Thermodynamics.
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No idea about the quality of wikipedia ...
But this is more or less what I learned in physics: https://en.wikipedia.org/wiki/... [wikipedia.org]
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Religion tells you something for sure, and you can believe it in all eternity. Science tells you not to believe anything, but to take anything as an hypothesis, which can be tested, and that every assumption might turn out as being wrong
Can I cite you the next time (i.e. a few milliseconds from now) someone here on Slashdot yells "the science is settled" or "scientific consensus"?
As an example: For a christian, performing satanistic rituals is soimething you should never do, as it is a direct way to Hell. For a String theorist on the other hand, it's quite important to be able to calculate something according to Loop Quantum Gravity, so he might be able to devise an experiment that can test the different predictions of each theory.
This is a false dichotomy and a dangerous example. In facts, even scientists know there are "forbidden" practices that can lead them far from the path of science: it is called departing from the scientific method. Unfortunately, you are partially correct: nowadays scientists like to trash the scientific method and perform unscientific practices.
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But just asking "What if?" as such is not useful. It gets useful, if you also answer that question with an experiment to check if or not if. So yes, you can ask: What if all climate scientists are wrong? As a question, this is ok. But what are the conclusions? It would mean that current Physics would be unable to a) measure the interaction of infrared
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Religion tells you something for sure, and you can believe it in all eternity.
Well, better to say religion tells you about human nature, which isn't hasn't changed yet as far as I can see. The ancient religions were never about answering the question "how does the world work", which should be no surprise since empiricism was thousands of years away. They are about answering the question "how should I behave in this world", which is still a more powerful question IMO.
Science tells you not to believe anything, but to take anything as an hypothesis, which can be tested
While true in a hand-wavy way, science does rest on a core set of untestable assumptions that can be summarized as "i
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Belief in "facts" whose origin one does not understand is indistinguishable from religion, even if the "facts" are correct.
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Outside of your measurements you have nothing, and all theories diverge wildly.
Well, yeah, science is all about explaining measurements, otherwise you just have story-telling.
And the arguments are like those about the number of angels on the tip of the needle.
Pretty much the opposite, since quantum mechanics is all about trying to explain crazy stuff that has been observed, instead of trying to make up crazy stuff out of boredom.
Actually, discussions about how many angels can dance on the head of a pin led to modern science, as they made it clear that angels and demons may be a useful tool for talking about psychology, but just lead to nonsense when talking about phys
Physicists Disagreeing (Score:4, Informative)
Physicists Disagreeing is not news. Physicists Disagreeing is science doing what science does.
Re: Physicists Disagreeing (Score:3)
Itâ(TM)s useful to know what they are disagreeing on.
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Pretty sure it actually means that physics has failed us and that it’s time to adopt a new system.
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Sorry, it's the opposite. Physicists disagreeing about fine points in interpretation of the data is what science is about, and what it's always been about. (Except, of course, that they weren't always physicists.)
P.S.: If you follow math you'll find the same thing. Proof is difficult. Goldbach's conjecture may be true, but just try to prove it. You'll find the same thing in any science. Proof is difficult, but when it's found, everyone either accepts it, or tries to find the flaw.
P.P.S.: Life in the
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Sorry, was in a rush and forgot the ;) at the end, though I had hoped it’d be obvious it was in jest and that no one here would seriously suggest tossing out the entirety of physics.
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I see. So because physics hasn't yet (note the use of time) solved the riddle, it must all be bollux and time to adopt a new system. Okay, what new system are you proposing? It better be damn good because physics can explain a lot. And it better use a lot of math because to go up against modern physics, it will need to compete. At that point, it will look like...physics.
Did you actually go to school?
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Sorry, forgot the ;) at the end. Shame on me for not considering that sarcasm isn’t obvious on the Internet, but I definitely had my tongue firmly planted in my cheek when I wrote that comment.
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Pretty sure it actually means that physics has failed us and that it’s time to adopt a new system.
Which one of the candidates has or had a plan for a new Progressive Physics . . . ?
That'll phyfix physics, and the rich will pay for it!
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It's even in the summary. The "disagreement" is one group analyzing some data using some methods and getting one result, and another group analyzing some data using other methods and getting a different result. It's not some Slashdotters calling each other names.
Dark Matter does not exist (Score:2, Informative)
From the moment I first heard about Dark Matter, until even after reading about the compelling reasons for its existence, intuitively I knew it did not exist. The entire reason for its existence is as a correction to observation. It is a fudge and always was a fudge since inception. How it ever made it so securely into the paradigm of cosmology, astrophysics, astronomy and physics, I do not understand. I always knew it would eventually be recognized as bogus, and guessed it would be unseated do to some unse
Re: Dark Matter does not exist (Score:2)
intuitively I knew it did not exist
The deeper problem with your expression is that, ultimately, you're expecting a "beautiful" theory. Something that is intuitively nice, makes sense, matches a sense of scientific aesthetics you've developed.
Sorry to break it to yo, but there's no guarantee that nature, or mathematics, or both, work this way.
Maybe there is a dark matter. Maybe not. In any case "intuition" has ultimately jack shit to do with it.
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Some of the dark matter candidates are pretty beautiful. Super symmetry is so famously beautiful that a bunch of physicists lost a bunch of bets when it failed to turn up.
One of the current best candidates, axions, are beautiful as well, potentially explaining dark matter, the strong CP problem, and, possibly the hierarchy problem.
Beauty is not a requirement, but with anything beyond the most superficial understanding you realize that dark matter isn't necessarily ugly at all.
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From the moment I first heard about Dark Matter, until even after reading about the compelling reasons for its existence, intuitively I knew it did not exist.
Well good for you. Unfortunately, intuition is garbage, especially when it comes to physics (or science in general). Very little about it is intuitive: do you intuitively know that the speed of light is a universal constant? That time travels slower in a gravity well than outside it? That the position/momentum of a particle are related through the Schrödinger uncertainty relation? No, you don't, because why the fuck would anyone. None of those things are within the realm of human intuition, which is ba
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Bullshit. Most physicists describe it as precisely what we don't know but ascribe the properties it must have in order to be consistent with observations. They never described it as anything but that. Stop putting your words in their mouths...and go get yourself a physics degree before showing the depth of your ignorance.
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From the moment I first heard about Dark Matter, until even after reading about the compelling reasons for its existence, intuitively I knew it did not exist.
genius. even to me, without the necessary background in physics and math either, it was clear from the first moment that 'dark matter' is just a metaphor, a placeholder to describe observations that can't be explained with current knowledge. because that's exactly how it is described by any half serious source.
maybe you shouldn't take these things too literally?
Re:Dark Matter does not exist (Score:4, Informative)
How it ever made it so securely into the paradigm of cosmology, astrophysics, astronomy and physics, I do not understand.
Because when it comes to fudges, everything else is more fudge-like than dark matter.
See, we already have reason to believe there are sterile neutrinos. All observed fermions except neutrinos come in both left- and right-chirality, while observed neutrinos only come in left-chirality. Further, observed neutrinos have been proven to have mass, and even before they were proven to have masses the usual quantum mechanics equations implied that if they did, then counterpart right-chirality neutrinos would also exist. And these counterpart neutrinos would, per the quantum mechanics, fail to interact with the strong, weak, or electromagnetic forces (thus why they were called "sterile"), but they would have masses and interact with gravity.
So, then we've got a whole bunch of observations of the universe that imply there's a whole bunch of mass out there that doesn't interact with the strong, weak, or electromagnetic forces (and thus is "dark"), but does interact with gravity. These include not just the usual galactic rotation curves, but things like the Bullet Cluster, which does gravitational lensing not as if it has two separated centers of mass on its wings (which its visible matter most definitely is), but one central concentration of mass (which would have to be non-visible).
Then there were the observations of galaxies whose apparent rotation curves were much slower, relative to their visible mass, than most others. That doesn't make any sense at all if rotation curves are determined by visible matter; you have to invent new patches to any non-dark-matter explanation of galactic rotation curves to explain these cases, while with dark matter you say, "Collisions between galaxies can just by random chance change their dark-to-visible matter ratios; if dark matter is true, we'd expect to see some low-dark-matter galaxies."
So, "sterile neutrinos exist and make up much of the mass of the universe" explains a bunch of observations both at cosmic scales and quantum scales. A computer model of tidal forces just plain doesn't; it "solves" the usual galactic rotation problem without explaining the unusual cases, or the Bullet Cluster, or anything else.
Similarly, there's also the axions, which solve the strong CP problem in quantum chromodynamics, and also could have mass while not interacting with the electromagnetic force and having minimal interactions with the strong and weak forces. Like sterile neutrinos, they too can contribute to "dark matter" astronomical observations while also solving a quantum mechanical issue, instead of explaining away only one "dark matter" issue.
In short, many major "dark matter" candidates explain whole slews of astronomical observations as a side effect of very simple extrapolations of standard quantum mechanics, while all the non-"dark matter" theories are fix-only-one-issue fudges invented post-hoc to correct one class of observations.
That's how the consensus that there's dark matter became so fixed. Everything else requires multiple unrelated theories to explain as much as (e.g.) "sterile neutrinos" does all at once.
Cold Dark Matter (Score:3)
The neutrinos we know about have been established to have mass, yes, but since they are light in weight, it doesn't take much energy to make them zip around. It is my understanding that although not all, many of the astronomical observations supporting the existence of dark matter require cold, not hot dark matter like the neutrinos?
Wouldn't the sterile neutrinos also contribute to hot dark matter?
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intuitively I knew
You intuitions might be helpful for human-scale stuff, but they lack any value for the very large or very small. This is why we study physics, instead of just guessing.
It is a fudge and always was a fudge since inception.
How science actually works: something pops up that isn't explained by current physics. Scientists invent a variety of theories to try to explain this new data. It's not "a fudge", it's new science. Eventually, some of these new theories predicts some new data, giving those credibility, while the others fall by the wayside. We're still in
What is the consensus? (Score:1)
I mean, what is it going to hurt if they are wrong?
That's right... bring on the hate, pseudo-scientists!
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Errr....there is no consensus, that's why it is an open problem.
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Lol... I think you missed the point..
Consensus does not count, only irrefutable & tested proof, that is science... anything else is pseudoscience.
Re: What is the consensus? (Score:2)
I cannot tell if you are being sarcastic or not.
Sterile neutrinos? (Score:2)
Now, three physicists claim (Score:2)
Now, three physicists claim their observations of empty patches of sky rule out one possible explanation of the strange substance — that it is made out of unusual particles called sterile neutrinos. "I think that for most of the people in the community this is the end of the story," says study author Benjamin Safdi, ...
Well... three people anyway. Pretty grandiose of them to think they've automatically convinced more than that. Observations are not proof.
Dark matter may not actually exist (Score:2)
Chiraliry (Score:2)
The Geometric Unity model seems to predict that "dark matter" will exist but not as anything particularly exotic but as 'left-handed' particles alongside our own but we can't interact with them because "our" particles are right-handed. Yet, they're subject to gravity just the same so we can see their effect but not EM effects.
It's an interesting model that derives relativity, a version of the Dirac equation, Maxwell's equations and a cosmological constant that depends on local curvature of spacetime. Also