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Bram Sci

(more cosmic rays--other stuff soon!)

(more cosmic rays--other stuff soon!)

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I have a longer entry coming up about optical illusions in astronomy and about neutron stars (pulsars).

But first, I've been skimming through Physical Review Focus, which is great! A friend of mine from college used to be involved with this. The idea is that it's a semi-popular summary of physics papers in Physical Review, the fancy technical physics journals. And then it also links to the actual papers if you want to know more.

So here are a couple of links--unfortunately they're a few years old and I'll have to look up to see if the ideas are still current--apparently "doubly special relativity" is not the only game in town for explaining why we see cosmic rays with such high energy. Cosmic rays with energies > 1020 erg should be impossible, because particles with such high energy would collide with the photons of the cosmic microwave background, the radiation filling all space as a result of the Big Bang.

Massive neutrinos minimize the number of tooth fairies: crossing the thresshold of early 1999, massive neutrinos were still becoming accepted. I think the evidence is even more in their favor now. The idea is that these high energy cosmic rays could result from massive neutrinos that pass through space unimpeded and then collide with other neutrinos when they get close to us (hm, is that collision so likely??), releasing particles.

A later paper suggested that maybe intergalactic magnetic fields are stronger than previously thought. So super high energy cosmic rays could be deflected more as they pass intergalactic space--and even though so far we haven't seen them come more from one direction of space than another, that could be because of the deflection. And so maybe the cosmic rays come from relatively nearby active galaxies like M87.
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