Hubble Detects Smallest Known Dark Matter Clumps (phys.org) 56
Astronomers have detected dark matter clumps around large- and medium-sized galaxies. Now, using Hubble and a new observing technique, astronomers have found that dark matter forms much smaller clumps than previously known. Phys.Org reports: The researchers searched for small concentrations of dark matter in the Hubble data by measuring how the light from faraway quasars is affected as it travels through space. Quasars are the bright black-hole-powered cores of very distant galaxies. The Hubble images show that the light from these quasars images is warped and magnified by the gravity of massive foreground galaxies in an effect called gravitational lensing. Astronomers used this lensing effect to detect the small dark matter clumps. The clumps are located along the telescope's line of sight to the quasars, as well as in and around the foreground lensing galaxies.
Using NASA's Hubble Space Telescope and a new observing technique, astronomers have found that dark matter forms much smaller clumps than previously known. This result confirms one of the fundamental predictions of the widely accepted "cold dark matter" theory. All galaxies, according to this theory, form and are embedded within clouds of dark matter. Dark matter itself consists of slow-moving, or "cold," particles that come together to form structures ranging from hundreds of thousands of times the mass of the Milky Way galaxy to clumps no more massive than the heft of a commercial airplane. (In this context, "cold" refers to the particles' speed.) The Hubble observation yields new insights into the nature of dark matter and how it behaves.
Using NASA's Hubble Space Telescope and a new observing technique, astronomers have found that dark matter forms much smaller clumps than previously known. This result confirms one of the fundamental predictions of the widely accepted "cold dark matter" theory. All galaxies, according to this theory, form and are embedded within clouds of dark matter. Dark matter itself consists of slow-moving, or "cold," particles that come together to form structures ranging from hundreds of thousands of times the mass of the Milky Way galaxy to clumps no more massive than the heft of a commercial airplane. (In this context, "cold" refers to the particles' speed.) The Hubble observation yields new insights into the nature of dark matter and how it behaves.
I remember seeing a live report of this (Score:1, Troll)
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Re:The subject LINE. (Score:4, Insightful)
and cowardly modding (modding without giving a reason)
If you mod you can't comment though so how are you supposed to explain it?
That was my point! (Score:2)
That is what I criticized about Slashdot's code!
And somebody downmodded my reply to my own comment (to mention a mistake I made) as (-1, Troll)!
Jesus fucking Christ, I'm surrounded by retards!
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Any chump that starts his sentence in the topic then continues in the comments block SHOULD be downmodded.
Fuckin' A
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Now, I agree he shouldn't be imprisoned for it- but if you think the concept of freedom of speech means that people have to listen to your dumb ass, you're sorely mistaken.
Moderation is not enforcement. It's judgement by a random selection of your peers on your commentary.
Sadly, it's not perfect, which is how you got an insightful mod for that drivel.
Astronomers have detected dark matter clumps... (Score:2, Insightful)
So, that being said: what they detected isn't dark matter, right?? they detected a smaller and smaller area or where dark matter should be. So it's like looking at a black hole -- you can't actually SEE what you're looking at, only infer that it's there because of the way things act around it.
Riiiiight?? Or have I been dr
Re:Astronomers have detected dark matter clumps... (Score:5, Informative)
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Re:Astronomers have detected dark matter clumps... (Score:5, Informative)
Because gravity affects spacetime. The common analogy is that mass is like a bowling ball on a trampoline, which would alter the straight-line trajectory of any ball rolling across the surface. Similarly, light is travelling in a straight line, it's SPACE that's warped.
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I mean, black holes are weird, man. The density is infinite, and that's kind of a mindfuck on its own. I don't think normal analogies work once you reach situations where one variable is infinite.
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It's a bowling ball heavy enough that the curvature becomes vertical.
Re:Astronomers have detected dark matter clumps... (Score:5, Informative)
Energy is the same thing as mass (remember E = mc^2), so yes, it is affected by gravity, but not by much because you have to divide by c^2, a very big number.
Newton described masses pulling each other, he never knew how though. Einstein hated "spooky action at a distance" in Quantum Entanglement, and obviously hated it also in Newton's Gravity, and he worked out there is no "spooky Newtonian action at a distance" but that Mass(i.e. Energy) distorts spacetime, and things just move in a straight line from their own perspective (simple & genius - no spooky action needed). The genius of Einstein is that he gave us why the speed of light is the upper limit, gravitational light bending, relativistic time slowing (used by GPS satellites), and gravitational waves (which took us exactly 100 years in September 2015 to detect (not see) after he predicted it! Amazing!) I cried tears of joy listening to the press conference when they announced gravitational waves were true. Einstein won the Nobel Prize for the Photoelectric Effect (i.e. solar panels, lasers and led lights, why UV only burns and doesn't kill us, why fires give more infrared warmth than light, why blue things are blue and pink things are pink, and why red things are red in weak light and still red in bright light). Our world today would not exist without dear Albert.
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Light has no rest mass. It does have a mass that depends on it's frequency, representing m = E/c^2. If you stopped it, it would cease to have any frequency, so it arguably wouldn't have any mass. (OTOH, neutrinos turned out to have a tiny bit of mass after all, and it wouldn't surprise me if light had a rest mass too....but a VERY small amount.)
FWIW, "bending space-time" by gravity isn't certain. It's a well-tested model, but that just means it works everywhere we could test it so far. It is, however,
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Of only you could read ... (Score:5, Insightful)
"Dark matter" is defined as "this gravitational effect that our theories don't yet predict, and where we don't know where it's coming from.
Granted, it is the most misleading term in science, since "big bang", but here we are.
As you can see, it has a gravitational effect. And sadly, nothig else AFAWK.
So you can see its effect on regular bright stars. Kinda like black holes.
(And frankly, I wouldn't be surprised, if it turns out to be black holes of some weird kind. ;)
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The ordinary, photon interacting matter (often called baryonic matter) is mainly accounted for, so astrophysicists know how much baryonic matter exists, and where it is in the Universe.
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Granted, it is the most misleading term in science, since "big bang", but here we are.
Georges Lemaître actually called it the "Primordial Atom", but because he was a Jesuit, the atheist Fred Hoyle - a proponent of the Steady State theory who was philosophically opposed to the theory because it smacked of special creation - mocked it by calling it the "Big Bang". The name stuck, but Lemaître got the last laugh because he turned out to be correct. Hoyle then went on to further improve scientific discourse by developing the "junkyard tornado" argument used against abiogenesis by creat
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> I'm sorry, I thought they couldn't detect dark matter what-so-ever: cold, hot, or diet.
It's "dark matter" because it hasn't been detected other than by gravitational effects at cosmological scale. That's all it _really_ means. Please don't conclude how exotic it is from the name.
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It isn't just matter that hasn't been detected other than by gravitational effects at cosmological scale-
It's matterish stuff that doesn't appear to interact with photons *at all* at cosmological scales.
It's actually a significant difference. They bend space time, but they don't interact with photons.
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Isn't that what I just said?
> it hasn't been detected other than by gravitational effects at cosmological scale.
And if I may point out:
> doesn't appear to interact with photons *at all* at cosmological scales.
The ability to detect photonic interaction at cosmological scales is limited by many factors. Galaxies at cosmological distances are detectable because they have many stars radiating, and even supernova radiating. Some dust and gas on interstellar scales is detectable by scattering, such as visi
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The ability to detect photonic interaction at cosmological scales is limited by many factors.
Complete nonsense.
Can we see galaxies outside of our own?
That's because the dark matter around us does not occlude them. It's gravitationally active, but does not interact with light- it is *transparent*
This can be distinguished from highly dense baryonic matter, which is *black*, not transparent.
There isn't a lack of photons- there are plenty of photons. What there is, is something there that appears to be mass, but doesn't stop those photons.
You're trying to conflate dark matter with dust- and it is
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Excuse me, but what? I carefully distinguished cold baryonic matter like dust from the missing matter because it is detectable. This does not mean that the "dark matter" is not baryonic. If it's cold and dense, such as asteroids, planets, planetisimals, and even planets, it won't be detectable except if it's in orbit around a star, and in pretty close proximity to optical instruments available to astronomers. It's why I'm giving the idea of interstellar or even intergalactic planets such attention. They're
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Excuse me, but what? I carefully distinguished cold baryonic matter like dust from the missing matter because it is detectable.
This does not mean that the "dark matter" is not baryonic.
Non-sequitur.
cold, dark mass is detectable. It is detectable because it eclipses. It occludes.
There is a lot of missing mass in the milky way. In fact, there is *more* missing than what we can see.
Some dwarf galaxies have as much as 99% of their mass missing.
These wouldn't be visible at all.
I'm sorry but these do mean that dark matter is not baryonic. Period.
Or that it does not exist, and our explanation of gravity is wrong. But then we run into the problem that no alternate theories of gravity do a
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Normal (photon interacting) matter clumps together and releases the potential energy as heat. Dark Matter does not interact with photons, and that means that Dark Matter can't release that energy by emitting photons. So Dark Matter has no chance to cool down after collapsing into a planet. So any larger aggregation of Dark Matter will disperse itself again because some of its particle reach the second cosmic speed and leave the gravitational center again.
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You're presuming that there is only one kind of dark matter. Since 90% of the universe is dark matter, I see no reason to expect it to be homogeneous. There could easily be multiple varieties of dark matter, some of which acted as if they were photons, and others acted like protons, neutrons, etc. In fact, there could be 9 incommunicado sets of such dark matter, each as large and diverse as the visible universe. Our current theories don't justify the assumption that such exist, but then they don't expla
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I use just a single property all cold Dark Matter has in common: No electromagnetic interaction. And that means: No heat releas (hence the name: cold Dark Matter). And that fits with observational data. Dark Matter in galaxies for instance has to be distributed in a spheric halo encompassing the visible galactical disc to explain both the rotational and the lensing properties of the galaxies. And that means that Dark Matter does not form planet-like massive bodies. Otherwise Dark Matter would
Re:dark matter forms much smaller clumps (Score:5, Interesting)
Thus we can rule out that the gravitational lensing effects we see are caused by ordinary matter as we would at the same time see slight phase changes in the light.
There are other arguments that rule out ordinary matter. They have to do with the forming of the first atom cores during the big bang. We can see from the Cosmic Background Radiation that there were gravitational bound clumps of matter forming at temperatures that would have destroyed any ordinary matter clumps and turned them into an evenly dispersed quark-gluon-plasma. Thus there has to have been a type of matter that is not affected by heat (which is just photons), and thus not interacting with light, which was able to gravitationally bind the protons of the first atom cores together.
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Please excuse this off topic observation:
I just love Google. I searched for "Massive Compact Halo Objects". The first selection in the drop-down list was "Massive Compact Halo Objects for sale".
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Well, to be more correct, some planets are "dark matter", but most dark matter is non-baryonic dark matter. And it has to have been segregated from ordinary matter in some way since before Lithium synthesis happened during the Big Bang. Primordial black holes would do the job, but they're hard to justify. What keeps them from either growing too fast or evaporating (either of which would be detected)?
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We Were All Thinking It... (Score:1)
Dark Matter is a stupid name (Score:3)
Because it isn't actually matter.
It is a placeholder for what might otherwise appear to be missing matter in the univers which explains observed gravitation effects that deviate from the predicted effect based on the matter that we can measure. Other than this apparent gravitational effect, it appears to have no interaction with measurable matter whatsoever, so why call it matter in the first place?
Has anyone considered the possibility that there is an entirely different force of nature at work which we have not yet given a name to, and which is actually only perceptable with existing instrumentation when making observations at the largest scales?
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In Quantum Field theory, each force comes with a field and an associated particle, hence "matter".
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Whether it's matter or not isn't clear, and partially depends on your definition of matter. It's got to be either non-baryonic, or to have been in some other way separated from the visible universe at the time of the Big Bang. And it doesn't react with electromagnetic forces, like photons. And it reacts to gravity. That it's particulate isn't proven, but is quite plausible.
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Has anyone considered the possibility that there is an entirely different force of nature at work which we have not yet given a name to, and which is actually only perceptable with existing instrumentation when making observations at the largest scales?
No- the force we're observing is gravity.
The part that's upsetting, is that whatever the hell is messing with gravity there doesn't appear to interact with photons, which means it isn't baryonic.
It's not that there's an entirely different force of nature at work, it's that there's an entirely different of nature at work.
Something out there forms clumps that affect spacetime as if they were massive. But they don't appear to be baryonic matter.
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Forgot I can't use tag brackets
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