Decades-old Scientific Paper May Hold Clues To Dark Matter 93
sciencehabit writes: Here's one reason libraries hang on to old science journals: A paper from an experiment conducted 32 years ago may shed light on the nature of dark matter, the mysterious stuff whose gravity appears to keep the galaxies from flying apart. The old data put a crimp in the newfangled concept of a 'dark photon' and suggest that a simple bargain-basement experiment could put the idea to the test. The data come from E137, a "beam dump" experiment that ran from 1980 to 1982 at SLAC National Accelerator Laboratory in Menlo Park, California. In the experiment, physicists slammed a beam of high-energy electrons, left over from other experiments, into an aluminum target to see what would come out. Researchers placed a detector 383 meters behind the target, on the other side of a sandstone hill 179 meters thick that blocked any ordinary particles.
That's all well and good... (Score:1, Funny)
... but does it shed light on how to transform luminiferous aether into phlogiston? Personally, I suspect it has something to do with walking under a ladder while saying "bloody Mary" into a mirror three times, but I can't fit the proof in the margin.
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But, it makes the equations balance...
Re:That's all well and good... (Score:5, Informative)
But, it makes the equations balance...
That's how science works. The predictions of the current model fail - the equations don't balance. You'll get many competing hypotheses each with its own suggestion for a new something that makes the equations balance. There were quite a few ideas for "dark matter" including a few "we just got gravity wrong" ideas.
The was no doubt at all that something was missing in established theory about galaxies and gravity - too much data to argue with. It's not like someone just invented dark matter out of the blue, then went looking for a use for it! There was no reason at the time to prefer any particular hypothesis.
Then the CMBR data gave us a fairly accurate measurement of the ratio of dark matter to matter in the universe long ago, and removed any doubt that it must be cold dark matter of some sort - not c or near-c particles, not a different theory of gravity, those ideas were falsified by the new data And in fact only the WIMP theory of dark matter accurately predicted the new measurement.
Dark energy is still early in this curve. There's no doubt about the data: there's something we don't know about the universe at very large scale, and it's the dominant effect at that scale. There are a bunch of hypotheses about what it might be, but that's about it right now.
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I like the Ell Donsaii theory of dark matter(Ell Donsaii is the latest scifi phenomenon for the unwashed masses, including myself) which is that it's tied into the 5th dimension where she does all her quantum entanglement stuff, which the stories are based around. The idea is at the end of the last book to come out was that there was a quantum entanglement limit when it came to traveling long distances, and this somehow affected gravity at galactic distances. The end of the book had the line,"Huh, so tha
And they saw nothing (Score:3, Informative)
TFA says the experiment saw nothing, and that this somehow rules out certain masses of dark photons.
Lose Dark matter with this one weird trick (Score:5, Insightful)
This story seems like click bait the way it just leaves it as a cliffhanger. so you bombarded an aluminum plate and .... a superhero aluminum man emerged? what what?.... how did this submission get promoted to a front page story? I'm surprised it did not end with "your jaw will drop when you see what happened next".
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Physicists hate this loophole. Turn ordinary matter into dark matter without changing your lifestyle!
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This story seems like click bait the way it just leaves it as a cliffhanger. so you bombarded an aluminum plate and .... a superhero aluminum man emerged? what what?.... how did this submission get promoted to a front page story? I'm surprised it did not end with "your jaw will drop when you see what happened next".
Just bad journalism. If you have to read more than 3 sentences to get to the end of the story, then you're reading an advertisement, not an article or an abstract. Journalists are paid by their subscribers to save them the trouble of going out and getting the story themselves. Advertisers are paid to generate interest, not to satiate it. The problem is that slashdot is supposed to be about doing the former to sell the latter, but it has become about doing the latter to sell even more of the latter.
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The thing that freaks me out is what happens if a huge chunk of dark matter comes barreling through our solar system. It might only affect normal matter through gravity, but that alone could totally screw up the earth's orbit and kill the whole planet simply by passing through nearby.
Yes, I know, I'm an idiot for scaring myself, but doesn't the concept sound horrendous? I mean, how could we fight that? We wouldn't have a chance.
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The real question is why if dark matter makes up the majority of the universe is there none if it within the solar system? We know there is none because if there was any significant quantity it would show up the orbital mechanics of the planets and General Relativity has those nailed to the wall with a sack full of six inch nails.
So if dark matter is real then we have to also believe the solar system in which we live is "special". At this point the whole concept falls foul of Occam's razor in my view.
I also
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Yes, by not seeing something under know conditions, you can rule out some possibilities. If the particles had properties withing a certain range they would have shown up in this experiment - since they did not, we know that the particles do not have properties in that range (assuming the experiment was done correctly).
This sort of null experiment is common in many types of science.
"The data come from" (Score:1)
I suppose that I've been around here long enough to not expect any better.
Re:"The data come from" (Score:5, Informative)
I am not too sure what you are complaining about, "data" is plural by strict definition, if not common usage.
Re:"The data come from" (Score:5, Funny)
~(xkcd)
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I wish I had mod points for you.
Re:"The data come from" (Score:5, Informative)
The collective noun for data is set: one talks about a set of data in the same way that one talks about a herd of cows. Data is just a normal nominative plural, not a collective noun.
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"Data" can also be used as an "uncountable" or "mass" noun, which is it's common usage.
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It isn't, I'm afraid. A 'herd' or a 'flock' etc. are a grammatical class called collective nouns, which are indeed treated as singular. The word 'data' isn't (and here I am refer to the single word 'data', not some collection of many datums).
You can tell that they're not the same thing, try saying "A data indicates that..." - it doesn't feel at all right does it? The fact that it only work when prefixed by 'the' tells us that it is a true plural noun and not a singular.
However, language being something that
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FWIW, when I was a student thirty-odd years ago, I hardly ever encountered the plural-noun ("data are") form. I knew it was technically correct, but almost nobody tried to use it. If anything, the plural form seems more common now than it was then.
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ST:TNG settled 2 things for geeks: the pronunciation of "data", and the phrasing "data is".
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The data came from
I'd still use past tense given that the experiment was 32 years ago
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I am not too sure what you are complaining about, "data" is plural by strict definition, if not common usage.
I'm complaining about the tense of the origins of the data, and how that doesn't match the data itself
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It is *so* uncommon today that it is actively confusing and hard to read. And I believe it has always been wrong when applied to any modern concept of data. Data in the modern context is a fluid quantity, like water. The other usage is archaic.
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Data, as in the stuff that comes through your Internet connection, maybe. That is not the case here - this is scientific data, which is a set of individual measurements, very countable and not archaic at all.
But yes, "data" has essentially transitioned from being the plural of "datum" to being an abbreviation of "data set."
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[citation needed]. Dictionaries observe the way language has been used in the past, but do not codify the limitations by which language may only be used. The way words enter the dictionary is generally by tally that lexicographers keep in observing past use of words out in the wild, so to speak. Grammar texts and dictionaries are merely descriptive of the most common ways the ordinary commoner has used the word in order of popularity -- it does not prescribe the ways in which a word may only be employed.
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I'm wondering what you're complaining about...
That's the exact same text as in the Science news article.
Are you objecting to the present tense, or are you confused by the correct
usage of "data" as a plural?
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FREE: Leftover HE electrons (Score:5, Funny)
Available for free: 2.5E36 high-energy electrons (~ 10GeV - 100 GeV). Last used in 1982, kept in a pet-free, smoke-free particle accelerator.
Local pick-up only; bring your own magnetic container.
* do NOT contact me with unsolicited services or offers
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Yeah, those electrons you sold me... they won't couple. It's as if they all have the same charge or polarity. You sold me queer electrons!
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No returns.
Re:FREE: Leftover HE electrons (Score:5, Funny)
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Oh, don't be so negative.
In The Year 2000 (Score:1)
Re:In The Year 2000 (Score:5, Funny)
It was hard but somehow we manag@#$%^&*@#$*&(*&#$ADSHJFHDKLJAF*(S*(&
NO CARRIER
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Confirming the Brady-Curran model (Score:4, Interesting)
Dark photons, or darkons [lindberglce.com], emitted by the boundary layer could simultaneously explain the missing mass and energy of the universe. Do I smell a Nobel prize?
Re:Confirming the Brady-Curran model (Score:4)
Well, perhaps, but the referenced study failed to find any, thus ruling them out as an option.
Granted, science technically treats negative results as equally important to positive ones; society and the Nobel committee, however, have a pesky bias toward positive results.
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"Granted, science technically treats negative results as equally important to positive ones"
No it doesn't. This case is a good example. If they had detected something they could have said "dark photons exist and have such and such properties." Instead, all they can say is "dark photons that have such and such properties do not appear to exist if such and such a theory is correct."
It's very important, and generally more difficult than a positive discovery, but negative evidence is always heavily qualified
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In particular, a negative result doesn't rule out the possibility that the dark photons could exist with other properties that the experiment didn't test.
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Just like you say -- the electrons were in a storage vessel, left over from another experiment. Except, the vessel was probably a storage ring -- kind of like a particle accelerator, but without the stuff to boost particles to higher speeds.
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I understood it to mean that other experiments produced - as a side effect - a beam of high-energy electrons, and the researchers set up this experiment that would run on the side whenever they were conducting whatever primary experiment that produced the beam.
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The LHC has about 115 billion protons in each bunch, and was designed for almost 3000 bunches at a time (I forget how many they ran before the shutdown).
Only a fraction of these protons collide, so there'll be plenty left when the beam quality is low enough for them to dump the beam and get a fresh one.
A common problem (Score:2)
In the experiment, physicists slammed a beam of high-energy electrons, left over from other experiments, into an aluminum target to see what would come out.
Let's all share! What do _you_ do with all those left over high-energy electrons you've always got lying around?
Not to worry, Sheldon's on it... (Score:2, Funny)
So thats what they were! (Score:2)
>> physicists slammed a beam of high-energy electrons, left over from other experiments ...I was wondering what was inside all those carboard boxes under the stairs.
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Just don't open the one labeled "microsingularities".
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weakly interacting != the weak nuclear force (Score:5, Insightful)
I got about 1 paragraph into the article before it became obvious that the author had no clue what the hell he was talking about. Maybe the old paper was better, but I don't have the patience to try to find out. From TFA:
They would interact only through the feeble weak nuclear force—one of two forces of nature that ordinarily flex their muscle only within the atomic nucleus—and could disappear only by colliding and annihilating one another
So many things wrong just in that sentence
1) Weakly Interacting Massive Particles (WIMPs) do have very low interaction cross sections (read: rates). There's sometimes an unfortunate ambiguity in the fact that phycisists have no imagination and gave two of the fundamental forces the names Strong and Weak. To say something interacts Weakly means that it interacts by exchange of W or Z bosons, not just that it has a low rate. However the WIMP interaction cross section has been known to be sub-Weak by several orders of magnitude for decades.
2) The Weak force's most obvious manifestation is in the production or absorption of neutrinos (beta decay or inverse beta decay) in a nucleus, but that's certainly not the only place it shows up; it's the mechanism for neutrino-electron scattering, muon decay, and a whole bunch of other stuff up to driving supernova explosions
3) Self-annihilation is the vanilla model for WIMP transformation, but there are plenty of sundaes-with-cherries-on-top models like self-interacting dark matter, which is discussed about 2 sentences later. Also, the chi is the symbol for the supersymmetric neutralino, often equated to a vanilla WIMP, and is not at all specific to the self-interacting dark matter model.
In short, cbtfaij;dr (can't bother to find an intelligent journalist; don't read)
Canada trolling (Score:2)
From the article (Score:3)
"All of this has to be done in a very tight straitjacket."
Pretty much sums up the whole subject.