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Decades-old Scientific Paper May Hold Clues To Dark Matter
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.
TFA says the experiment saw nothing, and that this somehow rules out certain masses of dark photons.
But, it makes the equations balance...
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I am not too sure what you are complaining about, "data" is plural by strict definition, if not common usage.
Available for free: 2.5E36 high-energy electrons (~ 10GeV - 100 GeV). Last used in 1982, kept in a pet-free, smoke-free particle accelerator.
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~(xkcd)
Data is indeed the plural of datum, however, it is plural like a herd [of animal] is plural. The herd is referred as singular ("The herd is ...") rather than plural ("The herd are")
Dark photons, or darkons , emitted by the boundary layer could simultaneously explain the missing mass and energy of the universe. Do I smell a Nobel prize?
How can I believe you when you tell me what I don't want to hear?
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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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".
Some drink at the fountain of knowledge. Others just gargle.
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)
Hah, that's not in anymore. Big Data are the new popular guy in town.
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"All of this has to be done in a very tight straitjacket."
Pretty much sums up the whole subject.
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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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