Dark Matter Grows Hair Around Stars and Planets (forbes.com) 171
StartsWithABang writes: Dark matter may make up 27% of the Universe's energy density, compared to just 5% of normal (atomic) matter, but in our Solar System, it's notoriously sparse. In particular, there's just a nanogram's worth per cubic kilometer, which makes the fact that we've never directly detected it seem inevitable. But recent work has demonstrated that Earth and all the planets leave a "wake" of dark matter where the density is enhanced by a billion times or more. Time to go put those dark matter detectors where they belong: in the path of these dark matter hairs.
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So your theory is that our current list of known particles is complete. Why is that likely, given that we've discovered new particles quite often in the last 100 years?
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Ah, so your argument is that because he doesn't have an adequate theory to replace yours, your flea bitten theory must prevail.
I don't know what the right theory is either, and neither do you. Attributing the extra gravity phenomenon to dark matter is nothing more than a variation on the G-d-of-the-Gaps. Got a problem with gravity, Dark Matter. You could give the alien guy Georgio with the electric hair a run for his money.
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Attributing the extra gravity phenomenon to dark matter is nothing more than a variation on the G-d-of-the-Gaps. Got a problem with gravity, Dark Matter.
For more than two decades you could have written:
Got a problem with beta decay energy conservation, "neutrinos".
Even as invisible particles, they were the best explanation on the table to explain beta decay. Then they got detected as well.
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Do you actually understand what you're speaking about? Dark matter is not, absolutely, any one thing. Dark matter is a reference to something we're unable to view and can only speculate about. Dark matter exists, by default, because we can not see it and we can demonstrate and measure that we're not seeing something. What that something is, is open to speculation. However, dark matter absolutely does exist. We can't see it - that's WHY we call it dark matter. It's there. We can measure and tell it is there.
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The way it varies though - mapping out the "dark matter" - suggests interactions with common matter both ways. So it's not like "the underlying fabric varies" - it really behaves like matter, forming clouds, strands, that "hair" - it's not a generic field or a generalized property of space "resulting in galaxies".
MOND suggests some unknown as of yet function mu(a/a0). If that function was to fit the observational data, it would be incredibly complex; nothing as elegant and common as common [something]/r^2 o
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I am not a physicist, but why does it have to be mysterious "dark" matter that's causing the discrepancy in the bullet cluster?
Show me where I said it has to be, and we'll go from there.
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I pointed out that non-luminous regular matter is also a valid hypothesis, so you are incorrect that there are only two reasonable hypotheses.
My point being - you are creating a false dichotomy. You are picking two possibilities, and saying dark matter is the more likely of those particular two. That is faulty logic.
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I am simply saying that you should look at other possibilities instead of discount them without any investigation. Sadly this has been standard practice in science as far back as we have records of scientific pursuits. When people base their world-view on a theory they fight to protect that theory with religious fervor. It is just human nature. Since I know about this nature I try very hard to fight it within
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Can't tell if this is part of the sarcasm implied in the first sentence. Changing the question when the answer doesn't work pretty much is what science is.
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Why?
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Wrong. Galactic rotation curves do not match with what is predicted by Newton or Einstein. The outer stars are orbiting much too fast. You either explain it with hidden matter, or you explain it by modifying gravity. The the fact in this case is the anomalous rotation rates. I suggest you need to look again into what 'actual' scientists do, because what they don't do is ignore interesting observations.
Or perhaps scientists don't have a clue how gravity works on a large scale.
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They're not manipulating anything. They are observing that there are numerous objects which appear to have a lot more mass than is visible. Unless you think there is something wrong with our Classical view of gravity, then the obvious answer is that there is a lot more matter out there than we can directly observe.
Fucking hell, there's nothing worse than some self-appointed anonymous poster on the Internet who is some fucking arrogant and stupid that he thinks he understands something better than the scient
Re:The dark matter between their ears (Score:5, Funny)
>> why is it that such arrogant fucktards always end up on /,
I for one welcome our SlashComma overlords.
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But no one says it doesn't exist locally. Quite the opposite, everyone thinks it does. It's just fucking hard to see.
It's not that cosmologists aren't willing to look at GR, and certainly are, but no potential quantum theory of gravity suggests an alternative to dark matter. And considering we all know there is physics beyond the Standard Model, and the potential for currently only hypothetical or even unpredicted particles, the idea that we should just toss out one of the most successful scientific theorie
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I don't have to provide alternative explanation to point out that what I see here is an ungrounded assertion. They're trying to manipulate facts to match the theory, not the other way around like actual scientists do.
No actually you DO have to provide an explanation.
We observe things happening. We are trying to make an explanation why they are happening.
Your claim that "they are not happening" when all observations and evidence and facts show 100% of the time over a few trillions of observations that your claim is WRONG.
It's completely on your head to show why your already-proven-incorrect "thought" is not wrong.
The facts you claim are being manipulated are right there in front of your face with no manipulation by anyo
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It's just a glitch in the program. It's a holographic universe, after all. Really, it's a holographic multiverse. We're just one of many!
Obviously, I'm not serious.
Or am I?
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Hey nitwit, the theory of dark matter is only there because of the facts. We call it dark matter because we don't know what it is, but we can see it's there [youtube.com].
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Practically all visible light that we see is emitted by atoms. So the only thing that we really see is atoms (emitting EM radiation).
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This logical fallacy is repeated so frequently that I think it needs its own name. I think "appello propter indispositionem" (appeal to ineptness) or "appellare multiplicitate" (appeal to complexity) are both appropriate. It's too complicated, we can't possibly be right! It's too hard, there's no way that's possible!
Re:The dark matter between their ears (Score:5, Informative)
Remember, when the facts don't match your theory
Correct. The facts don't match the theory. Galaxies could not hang together the way they do if all they consist of is the things we've already observed in the laboratory unless we change the law of gravity [to something enormously more complex - c.f. epicycles] or postulate the existence of something that interacts gravitationally but doesn't interact with light.
too bad for the facts
I don't get this. Nobody is ignoring the facts. That's why we need to change things. Dark matter is the heliocentric solution. No dark matter is the epicyclic solution.
The [difference between facts and] theory is easily explained
Don't know about easily. There's been a lot of "dark matter" theories that have fallen due to one or more inconsistencies with known physics.
by an abundant (making up 96% of the universe),
Necessary otherwise we have to change the theory of gravity
invisible,
If by invisible you mean doesn't interact with EM radiation then yes, this is required by the facts.
undetectable
It's not undetectable. If it were undetectable then we wouldn't need it. It's very detectable - its gravity is what makes galaxies hang together. Its gravity is what allows gravitational lensing to happen where there isn't any (visible) matter to make it happen.
magic
Definitely not magic. It has to agree with all the laws of physics. Conservation of momemtum, conservation of energy, speed of light etc.
"dark matter"
it's called dark matter because it doesn't interact with the EM spectrum. It neither emits EM radiation nor absorbs it.
that is everywhere and affects everything.
Actually, I think this is one of the great unknowns. Whether it's large numbers of light particles or smaller numbers of massive particles. Its primary interaction with the known universe is through gravity which yes, does affect everything, everywhere, at the speed of light.
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unless we change the law of gravity [to something enormously more complex - c.f. epicycles]... No dark matter is the epicyclic solution.
I completely agree with your post. However, I really wish people would stop using the "epicycle" as something to denote ridiculous complexity.
The reduction of epicycles [wikipedia.org] is NOT what drove the Scientific Revolution. Some facts:
- Medieval astronomers did NOT add "epicycles on epicycles." Owen Gingerich, one of the foremost historians of science and perhaps the world's greatest expert on Copernicus has spent nearly 50 years trying to stamp out this myth, which seems (according to him) to have originated
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Question: From TFA:
"Dark matter may make up 27% of the Universe's energy density, compared to just 5% of normal (atomic) matter, but in our Solar System, it's notoriously sparse. In particular, there's just a nanogram's worth per cubic kilometer."
So then, if it's 27% vs 5%, normal matter occupies roughly only about 0.185 of a nanogram per cubic kilometer? That seems on the low side.
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First it talks about dark matter in the universe in general and then (after pointing out that "... in our Solar System, it's notoriously sparse") gives the low density value.
So you can't apply the percentages that apply to the universe in general to the solar system.
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Correct. The facts don't match the theory. Galaxies could not hang together the way they do if all they consist of is the things we've already observed in the laboratory unless we change the law of gravity [to something enormously more complex - c.f. epicycles] or postulate the existence of something that interacts gravitationally but doesn't interact with light.
Spacetime is a continuum. Yes? Speed changes the perspective of time. Mass changes the perspective of space. No modification of gravity needed and no dark matter needed.
Put simply, there is less space where there is less matter. If you can wrap your brain around time dilation, wrapping your brain around space dilation should be simple.
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gravity is as instantaneous as people can detect - ie its not at the speed of light.
That is not actually known. We still haven't figured out if gravity propagates at the speed of light or not.
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gravity is as instantaneous as people can detect - ie its not at the speed of light.
That is not actually known. We still haven't figured out if gravity propagates at the speed of light or not.
In 1916 Einstein figured out that gravity propagates at the speed of light. We just haven't measured it directly yet.
Re:The dark matter between their ears (Score:5, Informative)
At the same time that all this was happening in cosmology, our particle physics friends were developing extensions to the Standard Model. In many theories they predicted new kinds of particle: ones that just happened to have a lot of the right kind of properties that the cosmologists needed for dark matter. Voila.
Dark matter is the simplest, most parsimonious, most elegant known solution that fits the observational data.
Source: I'm an astrophysicist and I do a podcast, and one of my first episodes was on exactly this [askaspaceman.com].
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The planet Neptune was identified not by visual observation, but by mathematical calculation based on errors in the predicted orbit of Uranus. Something was causing changes in the orbit Uranus should have taken according to the Newtonian model, and what was missing was another planet. They then were able to predict where it would be, and later observations by telescope
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I kind of of thought of dark matter as, the matter of light that we cant measure at rest, but there is so much out there it adds up.
Stars send it out, but when it strikes celestial bodies such as earth it collects. But most of it it falls out as earth moves along it's orbit as it's low interactive to all things including gravity.
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Why is it that astrophysicists "believe" in time dilation but do not "believe" in space dilation? Time and space is a continuum. They are inseparable as concepts. Energy is composed of spacetime and mass. When creating mass out of energy, spacetime is also created. The amount of mass determines how much spacetime there is; and therefore how much energy was used to create it.
"Length" is not a hardcoded value just as time is not a hardcoded value. There is less "space" at the edge of a galaxy. A flat galaxy t
Re:The dark matter between their ears (Score:5, Informative)
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I used "stop ignoring me" to grab attention and add some humor. It's not so much that it was being ignored, but that it was being questioned. 100 years of observations and geniuses, and not a single iota against it and a mountain of everything for it.
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"Remember, when the facts don't match your theory, too bad for the facts."
Our phlogiston-powered probe will find out how those dark matter hairs interact with the luminiferous aether through which our solar system is passing.
multiple lines supporting evidence (Score:2)
Re:The dark matter between their ears (Score:5, Interesting)
Ockham's razor: The facts suggest that gravitational force without visible source is being exerted.
Since the only known source of gravity we know is matter, we assume that gravitational source comes from some invisible matter, but we don't currently have any solid proofs for this specific assertion (although neither do we have any to the contrary, nor alternate viable theories).
It may yet appear that it does not. It may be some form of existence different than matter or energy; some wrinkles of spacetime or some sourceless gravity clusters. Since we don't know anything like that, "dark matter" is a convenient shorthand to describe that effect.
It's a bit like both with Rutheford's atom model and with Planck's quantization of spectrum.
The first - assuming that atom structure is a kind of "dough" with electrons being "raisins" fit the knowledge of that time explaining the "solid" nature of solids. It was blatantly wrong, proven by later experiments that found tiny nuclei in huge empty space. It was still a convenient shorthand for a time, to describe several observed phenomena and fit some observations - and for lack of better alternatives, it was accepted until disproven.
The latter sounded so incredible at first, that it was used strictly as a *hack* to obtain results that fit the experimental data, with belief that the underlying mechanism is vastly different, but undiscovered as of yet - so the "hack" was again a shorthand used to explain given phenomena, out of convenience, because again, we didn't know any better way to explain the behavior of photon emissions, or the stability of atom - even though practically nobody believed it to be true, just a conveniently close approximation. And then, surprise-surprise, more and more experiments confirmed - that "hack" was actually how the reality worked, that was not a mistake but a very unlikely - though ultimately true - description of the nature of atom.
Whether Dark Matter is another Rutheford's Atom, or another Planck's Quantum distribution, is to be determined and it will either be confirmed or invalidated. Currently, as a shorthand explaining the observed phenomena, it's doing pretty well.
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Maybe it is. Suggest a better alternative though. We're sticking to this one as long as we don't have any better.
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Well, bring up an alternative that explains everything PLUS what DM does, BUT BETTER. ***THAT*** is how you do science, not just go "Oh, pooh, it's wrong. Prove me incorrect!".
GRAVITY is a "magical invisible thing". MASS is a "magical invisible thing", if all you're going to do is call something "magical invisible thing", then what the fuck are you standing on this frigging planet for? FLY AWAY. Because magical invisible things can't prevent you doing it, can it.
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Yes, it would - given a theory fully consistent with the observation without the "god-like" dark matter. Which we don't have.
So until either a workable alternate theory is developed, or we manage to disprove Dark Matter through other means (e.g. discovering it's not actually matter) it's there to stay.
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I read that as " a nanogram's worth per pubic kilometer"
0_o
that, coupled with the hair thing... wow, the human mind hey?
Re: PPK (Score:2)
Ya, dark matter grows hair around Uranus kinda grabs a headline...
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Increase sensitivity! (Score:2)
if we were to position our detectors in the wake of one of these hairs – if dark matter behaves as we expect it to — the sensitivity of our dark matter detectors will improve by a factor of one billion, immediately.
No it wouldn't. The sensitivity of the detectors doesn't change at all.
When you walk into a bright room, it's not bright because your eyes have just magically got more sensitive to light.
Slashdot is not your personal blog (Score:2, Insightful)
Please startswithabang, go away.
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Please startswithabang, go away.
And take away that wake of credulous Forbes links where the density is enhanced by a billion times or more.
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What the hell? Why? Seems like the articles he posts are interesting and on topic for a nerdy site.
Maybe you should go away.
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The second link has his username embedded in it ... which essentially means he's publishing links to articles he's put elsewhere.
So, yeah, one can see how it's a little self-promoting.
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I've seen them come an go over the years but this is probably one of the least benign cases of self promotion.
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this is probably one of the least benign cases of self promotion.
http://dictionary.reference.co... [reference.com]
So lets reverse what you just said. This is the most harmful case of self promotion. Is that what you meant to put there?
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I don't entirely disagree ... but a lot of people prefer not to see something submitted which boils down to "hey, look what I have over here", especially if that submitter might actually benefit from the self promotion. And most especially if they don't give us the courtesy of adding the disclaimer which says "I'm on the payroll and this is mine".
So, like when Nerval's Lobster gets something accepted which inevitably links back to dice.com, we pretty much know he's a paid shill who gets preferentially publ
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Because this site is a news aggregation. If we wanted to read every thing he posted then maybe it would make sense to, oh I don't know, subscribe to his site?
His stuff is mildly interesting, but I'm sick of the 2-3 people who treat Slashdot as their personal blog. It used to be that people avoided getting linked to Slashdot for fear that it takes out your server. Nowadays you do your best to link every shitty click-bait article to Slashdot for the ad revenue. Everyone. As in we see his shit multiple times a
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Please startswithabang, go away.
Or at least learn the minimum necessary to post reasonably accurate summaries. I don't even have to go to the linked article to know that the research did not "demonstrate" what he claimed. What the research did was theorize about what happens when planets pass through dark matter, and demonstrate that such an effect is consistent with, in other words predicted by, current theories.
Demonstrating that dark matter is concentrated that way by a passing planet would mean detecting the dark mark and measuring th
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Please startswithabang, go away.
Right, please bring back Bennett Haselton instead! Please!
WTF?!? Is the OP serious? startswithabang seems to be one of the best serial-posters here.
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WTF?!? Is the OP serious? startswithabang seems to be one of the best serial-posters here.
Yes the OP is serious. Seriously disappointed that someone thinks there's anything "best" about serial-posters.
I guess Slashdot has turned into a personal blog for a few.
The occasional article is not an issue. The flat out serial posting of every one of his articles while at the same time having zero contribution to the site means he's using the site as a personal cash grab with Dice's support.
But hey I guess that's what Slashdot has turned into these days. Page hits for nerds, adclicks that matter.
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Yes, there is a guy here with a gun to my head, please send help! (or don't, because that was a terrible attempt at sarcasm...)
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But props to the guy - he has improved his posting somewhat the last couple of months, and has squeaked back into being worth paying attention to. In particular, in this one he STARTS with a link to TFP (that The FUCK
String theory? (Score:2)
Does this have something to do with string theory?
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Not much of a link, but afaik about as much of a link as it's possible to get between string theory and experiment.
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I have some dark matter and hair growth around my bottom star. Strings don't work for me. So no.
Try swallowing a string tied to a strip of muslin cloth. That should eventually help with the dark matter thing.
It stings... (Score:2)
Prézeau’s work is particularly stinging for me, because about a decade ago, as a graduate student, I was asked by my advisor to consider this problem, which I did. But in my analysis, I only considered the effect that the passing dark matter would have on the planet’s velocity, not of the density enhancement in the planet’s wake.
Ya man i know what you mean. I almost solved a quantum formula for gravity myself as my advisor asked me to solve a similar problem. But all i did was use formulas like mg(h2-h1)=E and assumed frictionless spherical cows.
Huh (Score:1)
So the Universe is made up of hairy balls... that explains a lot.
growing up so fast... (Score:1)
So, in the chronology of the creation of the universe, we've officially hit the puberty epoch. Congratulations, universe! You are growing up so fast.
I guess you could say (Score:2)
Those are some big hairy balls...
Experiment 1 (Score:1)
Send some politicians and Comcast executives into the wake stream for a few decades and see what happens to them. Don't waste perfectly good chimps.
The Sad State of Astrophysics and Cosmology (Score:1)
G R A V I T A T I O N A L * * * W A V E S (Score:2)
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Possibly, but it's going to be invisible to any of the light spectrum we work in, though I do wonder if would be something neat to have the ladies caress your invisible locks of dark matter hair (sounds better than hairy dark matter)..
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Yours too, glad I read it.
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Look at the size of that boy's heed.
I'm not kidding, it's like an orange on a toothpick!
Well, that's a huge noggin. That's a virtual planetoid.
Has it's own weather system!
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Thing is, Aether was meant to be an "anchor" - a selected reference frame for movement of light. Meaning it to be directly, firmly bound to EM radiation, an essential concept related to electromagnetic waves.
Dark Matter is completely oblivious to Electromagnetic spectrum, specifically entirely ignores it.
It might be some kind of aether, some field that is a source of gravity, that is fixed in space and has its own specific frame of reference. But it's definitely not what was discussed as the Aether in times
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"which "original" Aether theory are you formally referencing?"
The one Michelsonâ"Morley experiment failed to detect.
dark energy may be more related to aether (Score:2)
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