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.

Comments

And they saw nothing

[Anonymous Coward]

TFA says the experiment saw nothing, and that this somehow rules out certain masses of dark photons.

Re:"The data come from"

[Brett Buck]

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"

[Anonymous Coward]

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.

Re:That's all well and good...

[lgw]

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.