There is another interesting result from the astrophysics community today, this time from the Alpha Magnetic Spectrometer experiment, which is located on the International Space Station.

One of its tasks in recent years has been to measure protons, anti-protons, and helium nuclei that are present in high energy cosmic rays, and to record where they are coming from and how much energy they carry. Our best models of the Universe at present predict that these cosmic rays can be generated from a large range of objects, from pulsars to distant supernovae. And these models predict that at higher energies, the cosmic rays should contain many more protons than antiprotons.

Except they don't.

According to these new AMS results, while the fraction of anti-protons does decline in higher energy cosmic rays, it does not drop as much as the models predict. In fact for much of the energy range studied the fraction stays constant. In addition, the momentum-to-charge ratio observed in higher energy protons and helium nuclei were higher than predicted by current theories.

So why should it be so?

Pulsars produce cosmic rays, but they are not believed to be powerful enough to generate anti-protons. Supernovae do produce antiprotons, but not in the same way and not at the energies and quantities being seen here. One theory remains though, and it is a very tantalizing prospect. 

For many decades now we have known that the more than 80% of the matter in the Universe is in an unknown form, referred to as dark matter. We know very little about it, and it has never been directly observed in the labs on Earth. However we do suspect (or at least many leading theories predict) that the particles that make up dark matter can annihilate with themselves. They are most likely their own antiparticle.

And that means that anywhere in the Universe where there is a sufficiently high density of dark matter, they will be self-annihilating. And if they are massive enough (which is widely believed to be true) then each collision will generate a number of high energy protons and anti-protons, along with other particles. 

And that means that many of the thousands of proposed dark matter models also predict additional high energy cosmic rays reaching the Earth, and that these additional cosmic rays will contain a higher fractions of anti-protons than from other sources. Could that be what the AMS has detected? Could they have just glimpsed the first evidence of dark matter collisions?

Of course the real test will be if there is a 'bump' in the energy spectrum. The cosmic rays generated by dark matter annihilations are produced with a very specific energy - essentially they cosmic ray energy matches the mass of the dark matter particle. As the cosmic ray travels, it interacts with other particles and fields and the energy changes slightly, so what we would actually see is a higher number of cosmic rays at a specific energy, and then gradually declining at lower and higher energies.

But alas, the new data released by the AMS is just not detailed enough to see this. Maybe there is a bump, maybe not. It is just too early to tell what they have really seen. And if it isn't dark matter, then the theorists will have to go back to their chalkboards and find an explanation for these unexpected results.

Now the AMS will have to make more measurements, and add more data points to their study, and the rest of us will just have to wait and see. Only time and more data will tell us what is really going on in the depths of space.