Thursday, January 29, 2009

In case you missed it: micro black holes are news again

I've been slack lately and not following closely the arXiv papers on black holes at the LHC.

As those who read Instapundit would already have seen, there is a new paper by some credible European physicists (original is here) in which they re-visited the question of how long a micro black hole created at the LHC may last. The previous perceived wisdom was that it would be a tiny, tiny fraction of second before they disappeared into a spray of decay particles, which (presumably) the LHC could detect.

As I understand it, the new paper suggests that for a certain model, the decay rate may in fact be many seconds, even minutes; time enough for a micro black to shoot off through the earth. But they still think there is no likely risk of accretion starting and overwhelming the much-slower-that-previously-thought-possible decay rate.

As some are commenting (see the second link above), this still seems a pretty big revision of what was considered possible from the LHC, even if the authors are still arguing that there is no danger.

I note that the authors of the paper acknowledge discussions with physicists Giddings and Plaga, who themselves still (as far as I know) are stuck in disagreement as to whether Plaga's warning last year that a micro black hole could be an explosive danger was fundamentally flawed or not. At the very least, it indicates that other physicists consider that Plaga is not to be dismissed as a nutter.

Also on the topic of danger from the LHC, New Scientist has an article about a paper looking at (if I can paraphrase it correctly) how to judge the probabilities of something going wrong when you are not entirely sure of what may you might create in the first place. The general gist seems to be that it is potentially riskier than you think.

The guy who runs the Physics arXiv blog is probably really getting up the nose of CERN now, as the effect of both of these recent papers is to make him start worrying about safety issues. Fox News's version of the story probably annoys them even more.

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