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Scientists' Biggest Search For Dark Matter To Date Just Turned Up Nothing (sciencealert.com)
Peter Dockrill, reporting for ScienceAlert: For something that's hypothesised to make up more than 80 percent of the mass of the entire universe, it's no easy thing to detect the existence of dark matter. That's the conclusion the world is coming to today, after scientists announced that a massive $10 million experiment to find traces of elusive dark matter particles had failed after an exhaustive 20-month search. "We've probed previously unexplored regions of parameter space with the aim of making the first definitive discovery of dark matter," said physicist Cham Ghag from University College London in the UK, one of the scientists who took part in the Large Underground Xenon (LUX) project based in South Dakota. "Though a positive signal would have been welcome, nature was not so kind! Nonetheless, a null result is significant as it changes the landscape of the field by constraining models for what dark matter could be beyond anything that existed previously."Ars Technica has more details.
I keep looking for my imaginary friend, but he's never there.
Well, the dark matter explanation feels a bit hacky anyway. Hopefully some better explanation will gain traction.
A null result is actually more valuable than an inconclusive result would have been.
. . . just follow my friend 'Harvey' - he'll take you straight to it, despite the funky geodesics.
Perhaps, if they built a giant flashlight....
"I don't think you appreciate the gravity of the situation."
I've abandoned my search for truth; now I'm just looking for some useful delusions.
From Ars:
The LUX detector (Large Underground Xenon) is designed to pick up signs of weakly interacting massive particles, or WIMPs, when they engage in one of their rare interactions with normal matter.
There are indeed other candidates for dark matter, WIMPs being only one of those. This experiment searched specifically for WIMPs, which only rules them out, while of course the other remaining candidates remain to be explored.
Does dark matter have anything to do with string theory? I thought those were more or less independent ideas.
The Quirkz Handbook of Self-Improvement for People Who Are Already Pretty Okay
Dark matter is proposed because galaxies hold together despite having greater rotational speed than 'normal' matter would keep together, yes? There's is presumed to be a black hole at the center of all galaxies, yes? How is the (equivalent?) mass of a black hole estimated? For instance, if matter is dynamically spiraling into this black-hole (not in a stable orbit), might orbital assessments of the black hole's mass be wrong?
nothing to do with string theory, it's the search for why the stars in even our own galaxy have the orbits they do, and why the cosmic microwave background has certain imprints in it
dark matter is today's epicycles
Ok then, smarty-pants, how does gravity actually work? Answer should include a solution to the three body problem.
"Wait. Something's happening. It's opening up! My God, it's full of apricots!"
The Michelson-Morley experiment was experiment that turned up nothing, and lead to the development of general relativity. Perhaps this experiment will also turn nothing into something.
When all you have is a hammer, every problem starts to look like a thumb.
A null result is only a "fail" if you're not actually interested in science.
Um, you do realize that scientists do have experimental evidence that dark matter exists indirectly, right? Not just one way but at least two different ways, scientists have been able to estimate the total mass of energy and mass. The problem is that the estimate of the known mass and energy that they have been able to detect is about 5% of the universe. That means 95% of the mass and energy is unaccounted. This experiment was a way to detect dark matter directly.
Well, there's spam egg sausage and spam, that's not got much spam in it.
It's a lack of understanding of how gravity actually works.
You idiot, if we understood how gravity works, we'd probably have gravity generators. Aircraft wouldn't need wings anymore, and spacecraft wouldn't need reaction motors either. Hoverboards would be real.
Are YOU using the TOOL, or is the TOOL using YOU? Think about it!
And also the huge affect it has on gravitational lensing -- or rather, there being far too much gravity within the galaxies producing the gravitational lensing for the amount of visible matter we know the given galaxy to hold.
Empty space is actually made up of vacuum energy which can be directly observed.
Second class citizen of the New Gilded Age
Funny how ACs who are entirely ignorant of a subject imagine themselves to be experts with great insights.
Second class citizen of the New Gilded Age
which has a dark side, but no matter
Pain is merely failure leaving the body
We'll find so much dark matter if I am elected, you may get bored with dark matter! Believe me, I agree, you'll never get bored with matter. We never get bored. We are going to turn this matter around.
Right, a theory. But if you can't count it, can't measure it, does it really exist?
But we can measure it. Its gravity reveals its existence, its quantity, and its location. So yes it exists. We just don't know what it is, and the detector experiments are testing theories about what it may be.
We also have pretty good estimates of the density of dark matter in the solar neighborhood. It amounts to 0.49 ± 0.13 GeV cm3. This means, if you weight 70 kg, your body contains about 34 trillion electron-volts of dark matter (or 6*10^-20 grams).
Second class citizen of the New Gilded Age
Unless.... the aether was dark matter all along!
The mass of the EM is accounted for in the 5% referred to above. All the "stuff" we can detect (mass and energy combined) only add up to 5% of the apparent total mass required to explain the effects we see.
The observations are not wrong. Measuring the velocity dispersion of stars in a globular clusters is not a much harder, or more conceptually difficult, than measuring the colour of a fluorescent light. Determining a galactic rotation curve is a bit more complex, but not much so. These observations have been done tens of thousands of times using many different techniques, sometimes by groups of astrophysicists who hate each other and would like nothing more than to discredit the person who got to speak instead of them at last January's AAS meeting. The observational evidence for dark matter is overwhelming. The modeling, on the other hand, has more assumptions built in. The key assumption is that gravity, in the weak limit, follows Newton's law of gravity, and there is a 400 years of evidence to support that.
Just because you are paranoid does not mean that no-one is out to get you.
Right, a theory. But if you can't count it, can't measure it, does it really exist?
You're not listening: There is experimental data. DATA says that dark matter exists indirectly. Measuring directly is the hard part. It's not theory. Again please read what I wrote above. Measuring the total amount of mass and energy in the universe, physicists are about 95% short of the amount for which they can directly account. So either every instrument and measurement they have is wrong; or you just don't understand science.
Secondly, string theory has nothing to do with dark matter. String theory is an attempt to resolve gravity with quantum mechanics. If String Theory never existed, there would still be the dark matter/dark energy problem. Please read up on some science before commenting further.
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But we just proved it doesn't exist.
No, that's not what TFA says at all. You can't even blame a misleading Slashdot headline here: you just made that up. A detector was built to find a very specific kind of matter. It didn't find anything. No real surprise, as there was never any reason to think it would - it was just the sort of detector we already knew how to build.
Hence, my theory is just as valid, that EM has both mass and is a wave
Yes, that's called "Quantum Field Theory", and it's what nearly everyone believes. Doesn't explain anything that dark matter explains, though, so no.
Socialism: a lie told by totalitarians and believed by fools.
So, um...indirect experimental evidence is not actually empirical. It is absolutely, completely un-the-same as experimental evidence.,
Um, no you don't understand. There is direct evidence that we can measure the total amount of mass and energy in the universe. However, 95% is unaccounted for if we count all the stars and planets scientists think exist. Therefore indirectly, dark matter is the placeholder for the matter that should exist but can't detect. They could have called it Zoidberg matter and it would be the same.
It's like looking at the ocean. With the naked eye we can only see the top layers of the ocean. Historically, sonar allows us to determine the depths of the ocean to be miles deep; however, until the existence of deep underwater vehicles, scientists didn't know what the bottom was like. They could only guess. They could not imagine that life exists near the Marianas Trench for example.
The case for dark matter is more inductive or abductive reasoning. Given certain premises based on our current understanding of gravity and our observations of the universe, dark matter makes sense. However, our observations could be wrong, or our models could be incorrect.
Yes everything in science could be wrong; however, you must prove that every one of their observations is incorrect rather than assume that because someone doesn't have all the answers, they don't have any answers.
Well, there's spam egg sausage and spam, that's not got much spam in it.
This is great timing. I like how the LUX researchers' conceptual description of WIMPs sounds exactly like neutrinos: https://medium.com/starts-with...
But we just proved it doesn't exist. The missing mass exists.
Um no. They haven't detected it yet does not mean it doesn't exist. it was an experiment failure. It's hard to prove a negative. That's like saying the Higgs Boson particle was proven not to exist until they detected it. See how silly that sounds?
Hence, my theory is just as valid, that EM has both mass and is a wave, and we're just confused little podlings who will have to go back and adjust our theories again, as we did over and over and over.
You don't have a theory. That's conjecture.
Remember, at first we didn't think light bent due to gravity.
Yes but that doesn't mean neither light nor gravity existed. We didn't know about the interaction between them could produce such results.
Well, there's spam egg sausage and spam, that's not got much spam in it.
No, it's Trumps all the way down! Or possibly it's some really bright people that will advise Trump all the way down.
"Yes, but vacuum energy still equates to 0 energy and mass *on average*" - Why? Is some vacuum energy negative?
Good point :-D
But I fucking told you so!!
I have nothing to go on other than my own impertinence and pigheadedness, but I am convinced that simply adding mass to the equation is not what is needed to solve it. Yes, our models look right when we add that mass, but I think it's something else going on. Something fundamental, misunderstood, and/or some emergent interaction of other forces.
Fucking beautiful explanation--you just have to figure out how to change those models without breaking the rest of the models. Nobody who has some clue as to what the fuck they are doing thinks that our models are 100% complete or 100% accurate--so standing around telling people they're wrong if fucking useless and contributes nothing to the search for the solution.
You want to be useful? Try getting your level of skill up to the same level as the people who are actually doing the work; because otherwise you're just another asshole spewing shit.
Yay! We are all saved!
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
>Now we "know" it's a particle and a wave.
No, it's a wave. The particle thing is just about the way your brain entangles with things.
https://www.youtube.com/watch?...
If you're impatient, jump to 23:00 and listen for a few minutes to be told the same thing by a real physicist.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Scientific theories are not in the same category as conspiracy theories or cockamamie theories.
What is the 'parameter space' that they were searching? Is it an accepted term in physics? I'd expect to find nothing in my parameter space except for variables (and a number of logical and conceptual errors).
Analogy - you are in a dark room with lit objects on the other side of the room and something heavy is on your foot but you can't see what it is.
Gravitational effects tell us that things are there but it's too dark to see them.
Unless.... the aether was dark matter all along!
Sorry, it doesn't work that way. Perhaps you should actually study the theories rather than reading the pop-sci executive summaries of them you would understand.
But sincerely I hope you're joking, but I'm too drunk, (6 shots 99 proof + 2 shots 60 proof), to tell the difference, and too many people are too fucking stupid to understand the difference.
Our universe exists 'on' the 4-dimensional soft skin of an 'onion'. Matter and energy as we see it deforms the surface of the skin, and it is this deformation that we perceive as gravity. What we call dark matter is simply the cumulative effect of the (contents of the) other skins of the onion on ours, which we cannot yet directly measure, having no way to 'focus our measurements' outside our universe.
Several solutions exist for special cases of the three body problem, but I'm sure you're after a general solution. As it happens a general solution to the three body problem has been shown to exist, by Karl F Sundman, which takes the form of a convergent infinite series, but as the series takes so long to converge it is practically useless.
Having taken a somewhat different approach to the problem, I have discovered a more practical and surprisingly elegant solution, but unfortunately /.s character limit is too low to allow me to post it here...
*I'll leave it as an exercise to the reader to figure out which bits are which ;-)
We proved we didn't detect it.
This means, if you weight 70 kg, your body contains about 34 trillion electron-volts of dark matter (or 6*10^-20 grams).
Only if it's uniformly distributed. If dark matter is black holes, then no. http://www.space.com/33122-dar...
Why are all corporate energy scammers called Randell?
It sounds like dark matter is thought to be made of particles of some sort. Could it instead be a force field of uneven density in space that interacts with the gravitational field in some way? Though the question then would be what causes the field I guess. But maybe that's an easier task.
It's spelled aether, not ether. If you're going to act like you know what you're talking about, at least spell it correctly!
When I first started looking into relativity as a kid, I remember getting stuck on that word. How was one supposed to pronounce that funny character (I mean the ligature æ)? I even tried making both vowel sounds. There was nobody around to ask, and I wasn't comfortable assuming the ether pronunciation. I filed it away, hoping that someday I would get the problem resolved by hearing an authority say the word.
Later in life, I notice everybody using the simplified spelling, and consequently the simple ether pronunciation. Yes, this allows some ambiguity with the chemical (CH3–CH2–O–CH2–CH3), but aside from that, it is a victory of the people against the elite.
But it's up to you. You can spell it ether way.
(||) Nehmo (||)
It sounds like dark matter is thought to be made of particles of some sort. Could it instead be a force field of uneven density in space that interacts with the gravitational field in some way? Though the question then would be what causes the field I guess. But maybe that's an easier task.
The way physics think nowadays, fields and particles are the same thing. A particle is a perturbation in a field that is realized.
(||) Nehmo (||)
Everyone knows if you are searching for something dark, you have to use a light to find it. ;)
Actually, the first name applied to this stuff was "missing matter". And many don't like the current term, "dark". Maybe a better one is "invisible matter", but it's too late.
(||) Nehmo (||)
There is an obvious candidate for dark matter. Not interacting, hard or impossible to detect, interacts with gravity (maybe). I'm talking about tachyons, possibly with net negative mass. Such a tachyon will have an internal FTL geometry but its external geometry may make it travel faster or slower than light. (A tachyons internal speed of light is a special local only value.) Objects with negative mass don't really work with general relativity, but then general relativity doesn't really work at FTL speeds anyway.
Ironically this is why conventional physics wont even consider the idea of dark energy as tachyons. FTL physics requires a different theory (based on a flat absolute FTL frame) which breaks general relativity above the speed of light. So one theory with absolutely no proof is rejected because of another theory with absolutely no proof. (Above the speed of light there is less proof for general relativity then there is for astrology..)
Below the speed of light Special Relativity is one of the most accurate theories in physics - above the speed of light..
You have it backwards. Our hypothesis to explain the DATA is black matter. The DATA does not (indirectly) show that dark matter exists.
No, you don't understand the data. The data says that there is an amount of the total combined amount of energy and mass; however only 5% of it can be accounted for if all the stars and planets in the entire universe is counted. The 95% we don't know what it is; therefore, it is considered dark. It's a placeholder designation. Scientists could have call it silly putty matter.
What scientists are trying to do is prove their hypothesis correct by proving dark matter exists.
No, they are trying to determine if one of their proposed methods might work in detecting dark matter. They know it exists; they don't know what it is. For example, scientists could only see the top layers of the ocean for a long time. Sonar could deduce that the bottom was several miles deep. Until the invention of deep sea vehicles scientists didn't know what was at the bottom; but they knew the bottom existed. They just didn't have the technology to determine what was there in detail.
Tomorrow someone could come up with a theory supported by experimental data that explains the data that has nothing to do with dark matter...,/
That someone still has to explain away the current 95% and why we can't detect with all the current instrumentation that exists. Again, dark matter simply means "matter we can't detect through current methods."
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DATA does not "say" dark matter exists. The indirect data we have suggests that as one possible explanation (and so far the only one that has survived critical analysis of numerous experiments).
What is dark matter to you? To scientists, it's matter we can't detect with current instrumentation. It's that simple. It does exist. Now could scientists be wrong. Yes. Absolutely. However you can't merely say there are wrong because they haven't found all the answers. If you have other plausible explanations please let them know. So far the best minds of science can't describe it in other terms other than "dark."
Well, there's spam egg sausage and spam, that's not got much spam in it.
so, the search was successful, then.
Star Trek transporters are just 3d printers.
Dark matter, which is a complete and utter fantasy to cover for the fact that we don't know how gravity works, reminds me of the last time scientists pushed baseless nonsense so they could keep their jobs and keep funding their research into knowingly wrong science. Anyone remember "The Ether?" which was allegedly what empty space was made of. As it turns out empty space is made of empty space. Who would have thought?
i've always thought the idea of "potential energy" is only a hack to adjust calculations of kinetic energy to fit the law of conservation of energy. so, same deal with dark matter.
Star Trek transporters are just 3d printers.
Scientists' Biggest Search For Dark Matter To Date Just Turned Up Nothing
dude, that's heavy.
Star Trek transporters are just 3d printers.
I see a bunch of jokes already on this one.
The other part is a bunch of people will probably get their PhD on finding nothing.
> Well, the thing about a black hole - its main distinguishing feature - is it's black. And the thing about space, the colour of space, your basic space colour, is black. So how are you supposed to see them?
Given that there may several exaquintrillion tonnes of asteroids, planetesimals, rocky planets gas giants, black, brown and red dwarves and even reasonably large stars, roaming around that we are only just beginning to be able to see, a large amount of dark matter may well turn out to be regular matter, just very hard to see.
That's a great point. Gravity however doesn't seem to have a particle yet, and we know and measure it and use it comfortably anyway. "Dark Matter" force seems to be a closer cousin to gravity than some other forces.
We have a certain model, a mathematical conception if you will, of how gravitation effects work. Based on that model combined with our observations, some scientists conjecture there needs to be more mass and energy, by a factor of almost 100 times, than what we can observe to make galaxies spin at the observed rate and not fly apart, etc.
You take that as direct empirical evidence of dark matter. I assert that this is not irrefutable empirical evidence of dark matter/energy. Obviously something is going on, but saying the model is 100% correct, and therefore dark matter/dark energy exists as postulated is weak and sloppy thinking. Walking back your position to say that dark matter/dark energy is a "placeholder" is disingenuous on your part and shows you are trying to walk on two sides of the fence here. It's a kludge, tossed into the model to make it work. It points toward something, but what that something is has not been determined yet, obviously. Otherwise we wouldn't be having this conversation. If it is a particle with mass then we have dark matter. I am not convinced that this is the case.
Here are some possibilities:
1) Everything is right with the model and we just need to try really hard to detect weakly interacting massive particles. This still leaves out the "energy" part of the dark conundrum, but hey, any detection would be awesome since we haven't had any yet. We can deal with the biggest part later, lets just get on the board here, right?
2) The model is way off, possibly due to some unknown problem with our understanding of gravitation at the macro-scale, and as a result there is no dark matter or dark energy. Not too far fetched, since we don't even know what causes gravity yet.
3) The observations are off. This is actually still a model error, but it would be a problem with our model of the observed information.
4) The model needs some tweaking. There is dark matter/energy, but the proportions are not what we expect, their interactions are not what we expect.
5) Our models are correct, but there is not way to directly observe dark matter/energy. The "placeholder" is recognized as a kludge and we go on about our business, quietly freaked out by the problem like the double slit experiment.
You analogy of sonar is completely wrong. That is direct observation. Definitely not what we have going on here. We do not have direct observation of dark matter/dark energy. We haven't bounced anything off of it. We haven't isolated it.
Look up inductive and abductive reasoning and tell me how I am wrong. Your analogy skills need lots and lots of help.
When the only tool you have is a claw hammer every problem starts to look like the back of someone's skull.
I assert that this is not irrefutable empirical evidence of dark matter/energy.
Then please refute it with evidence or observational data. So far no one has been able to determine that the data is wrong or the observations were incorrect. Also the dark energy/dark matter discrepancy was verified in at least two different ways.
Obviously something is going on, but saying the model is 100% correct, and therefore dark matter/dark energy exists as postulated is weak and sloppy thinking. Walking back your position to say that dark matter/dark energy is a "placeholder" is disingenuous on your part and shows you are trying to walk on two sides of the fence here. It's a kludge, tossed into the model to make it work. It points toward something, but what that something is has not been determined yet, obviously.
No one has ever said in science that anything is 100%. Even the best model for gravity (General Relativity) is known to have flaws in that it can't resolve quantum mechanics with gravity. But the best model is that there is 95% missing energy and matter. At this point it is a fact that there is a discrepancy and scientists do not know fully how to resolve it other than use the models which we know to exist and do work. Could they use other models? Sure but other models like String Theory have not been able to explain it either. I could speculate it to be space fairies and pixie dust but I don't have a good model either.
Otherwise we wouldn't be having this conversation. If it is a particle with mass then we have dark matter. I am not convinced that this is the case.
Again, no one has been able to explain it with other models.
You analogy of sonar is completely wrong.
In which way is the analogy wrong? My analogy was to show how limited observation and data was later to be resolved with better technology. It also showed how the absence of direct observation does not mean that no data exists and that some conclusions can be drawn. Science had long known that the ocean was miles deep but were not able to know exactly what conditions were like at the bottom. The instrumentation could only show the existence of the depth. Detailed knowledge of the oceans was limited to the top layers. Direct evidence says 95% of matter/energy is missing and that it has properties different than ordinary matter/energy.
Let's then try another analogy: The solar neutrino problem. For decades, the count of solar neutrinos coming from the Sun was 1/3 of what the Standard Model predicted. So either the data and experiments were wrong or the Standard Model was wrong about neutrinos. Koshiba and Davis won the 2002 Nobel Prize in that their experiments showed that the Standard Model was wrong in that neutrinos have mass.
That is direct observation. Definitely not what we have going on here. We do not have direct observation of dark matter/dark energy. We haven't bounced anything off of it. We haven't isolated it.
Um, yes, we do. We have direct observational evidence that 95% of the matter/energy in the universe cannot be accounted for if all the regular mass and energy is counted. So that leads to three possibilities: 1) the observational data of total mass/energy is wrong (but measured two different ways this seems unlikely), 2) the estimation of known mass/energy is wrong. (again, measured in different ways so it seems unlikely) 3) there exists matter/energy which cannot be measure by current instrumentation (therefore dark energy/dark matter) and the model of our understanding of the universe is wrong in some way (possible and that's what scientists are trying to resolve by trying to detect dark matter directly).
Well, there's spam egg sausage and spam, that's not got much spam in it.