Crab Nebula gamma emissions and the Large Hadron Collider

Posted on October 6, 2011


According to the BBC, astronomers observing the pulsar at the core of the Crab Nebula have observed gamma rays with energies far in excess of what current stellar models expect. The BBC wrote

[Dr. Nepomuk Otte and his colleagues] spotted gamma rays with energies of far more than 100 GeV, and there were further hints that there may be teraelectronvolt rays; that puts them nearly on a par with particle energies at the Large Hadron Collider.

If you recall, back when the Large Hadron Collider (LHC) was about to be powered up in 2008 there was a great deal of fear expressed by non-scientists that the LHC could result in the creation of black holes that might eat the Earth, or that the LHC might create theoretical “strangelets” that might eat the Earth. Regardless of the theory, everyone agreed that they were afraid that it meant the end of the world. I wrote a post debunking this lunacy by means of theoretical Hawking radiation, quantum mechanics, and some basic particle physics, but some commenters were not convinced. One went so far as to label the LHC’s creators as worse than Nazis because the Nazis weren’t trying to kill the entire planet, just commit genocide. *cough*cough*are-you-fucking-kidding-me!?!*cough*cough*

The main reason that the LHC wasn’t going to make Earth-devouring black holes was simple logic: scientists have observed collisions between galactic cosmic rays and the Earth’s atmosphere that have way more energy than the highest energy collision that the LHC can create. By “way more energy” I’m talking trillions of times more energy.

If the observational hints about the Crab Nebula are right and there are teraelectronvolt (TeV) gamma rays coming from the pulsar, then that’s another observation that might indicate that the LHC is safe. True, a gamma ray isn’t a cosmic ray – the former is a photon of light at really high frequencies and the latter is a particle of matter accelerated to very high speeds, but fundamentally the two are identical (you know, according to that old E=MC2 thing someone smart came up with). And who knows, when the scientists get around to figuring out why their stellar models differ from the observed gamma ray energies, they might find that the most likely source is particle collisions.

OK, so maybe that’s a stretch. Maye. But the Crab Nebula thing is still cool, and last I checked, the LHC has been run at half its maximum power (3.5 TeV, in March 2011). And if I twist an ankle out jogging, it’s pretty clear to me that the Earth’s still here too.

So much for the end of the world.

Image Credit: American Institute of Physics, from NASA originals

Posted in: Science