Thursday, April 21, 2011

Be Careful What You Read

Universe Today put up a paper by M. Villata of The Observatory of Turin 2 days ago, and has since taken it down. It seemed too good to be true. Here is the abstract:

"The gravitational behavior of antimatter is still unknown. While we may be confident that antimatter is self-attractive, the interaction between matter and antimatter might be either attractive or repulsive. We investigate this issue on theoretical grounds. Starting from the CPT invariance of physical laws, we transform matter into antimatter in the equations of both electrodynamics and gravitation. In the former case, the result is the well-known change of sign of the electric charge. In the latter, we find that the gravitational interaction between matter and antimatter is a mutual repulsion, i.e. antigravity appears as a prediction of general relativity when CPT is applied. This result supports cosmological models attempting to explain the Universe accelerated expansion in terms of a matter-antimatter repulsive interaction."

Click here for the actual arXiv preprint. It has been published as a paper in Europe.

So I asked an actual PhD. in Physics and general relativity expert what they thought, and this was their response:

From reading the abstract I'd say there's a 99% chance the claim is wrong. For this to be true, CPT would have to mess up Lorentz-invariance, which it doesn't.

Okay, browsing through the equations, (9) is not covariant. There goes GR. Btw, this equation has been tried and been reinvented numerous times before. People underestimate how restrictive general covariance really is.

I thought it was too good to be true. Of ALL the things in the universe though, the whole galactic filaments-void structure interests me the most. Why THAT structure? Well, I'm not overly worried. Astronomy is taking off like a bat out of hell, and Astrophysics isn't far behind. Cosmology though strikes me, at times and for the most part, as a bunch of weenies who like to disagree. Cosmology is the interpretations, and they are ALL over the map. Very frustrating, doubly so since the popular science magazines seem to love them the most.

This is our Universe on the largest scale. It kind of  looks like cobwebs. Welcome to our spider-verse.

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