Porno at CERN

Although I'm on holidays, I have a report due on a CERN seminar last week. Last Thursday, Irina Arefeva gave a talk about wormhole production at the LHC. The claim is that, in the context of models with the TeV quantum gravity scale, the LHC might produce not only black holes but also another class of objects called wormholes. There has been quite a lot of noise around this work, mostly in tabloids like the Sun and New Scientist, and the echoes resounded in the blogosphere too. Peter linked Irina's paper to an article that coined the term science pornography. Lubos, on the other hand, tried to point out interesting aspect of this direction of research. In this post I'll brood on the question if that paper is pornography or not.

Wormholes are solutions of the Einstein equations with equal time slices being not simply connected. The spacetime containing wormholes allows for closed time-like curves, which conflicts with our notion of causality. There exists a vast literature aiming to understand these weird objects. The questions is if they are physical or they are merely a pathology of Einstein gravity that should be discarded. One conclusion I would draw from this debate is that we are lacking tools to address some major questions in quantum gravity. In particular, the limitations of the sum-over-histories approach to quantum gravity become rather clear.

Pornography is notoriously difficult to define. The typical attidude is "I recognize it when I see it" (but, once you're watching, you might get accused of being too interested). It is difficult to draw a line beyond which science pornography begins. I can perfectly imagine social environments in which extra dimensions or supersymmetry are considered hard porno. Similarly, wormholes, just like nudity, do not equal pornography; it all depends on the wider context.

Still one can attempt a more formal characterization of pornography. In my opinion, one defining feature is certain blunt simplicity, going straight to the point and avoiding any philosophical divagations. The work presented by Irina matches that description quite accurately. The bulk of the talk was a review of wormhole solutions in general relativity. Solutions appropriate for ADD large extra dimensions were not mentioned. At the end of the day the claim was made that, since black holes are produced with geometrical cross sections, wormhole production should behave similarly. Why? The question of wormhole decays was not addressed at all. How would they differ from black hole decays?(the latter are expected to produce Hawking radiation, but wormholes do not have a horizon). In short, there was nothing that would improve our understanding of the subject. Yet, at this point, this could be just a bad talk based on a bad paper. What ultimately makes it into a vulgar porno is calling the paper Time Machine at the LHC. A cheap trick that is supposed to arouse the reader with the prospects of time travel. I'm afraid that this kind of presentation gives scientific research a bad name.

It's not that the whole subject of wormholes should never be addressed. There are certainly many interesting questions to be asked, that could at least help us understanding the limitations of our understanding of gravity. It doesn't take much to turn pornography into art. Try it. You may become Tinto Brass of particle physics :-)