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The Geneva area a few minutes after LHC startup April 14, 2008

Posted by dorigo in astronomy, humor, news, personal, physics, science.

I received this morning the poster of a workshop on Dark Matter searches at the LHC, which will be held in my University on April 22nd. This is a single afternoon of talks addressed to students of Physics, to educate them on the connection between particle physics and cosmology in view of the start of the collider this fall. Upon glancing at it, I immediately sensed the subliminal message it sends to whomever has been reached by the headlines on the recent lawsuit concerning the risk of black hole creation in the high-energy proton-proton collisions… Here is the poster:

The galaxy has of course nothing to do with an expanding black hole, but it still sends a sinister message. Let me say it here again: black holes will NOT be created at LHC. Scientists cannot even assess the chance of that happening, because the probability that 1) Large extra-dimensions exist in nature, 2) the scale of quantum gravity being both fine-tuned to allow black holes to be produced by LHC and not by past colliders, and orders of magnitude smaller than what it is most reasonable to conceive, is too small to be investigated meaningfully.

In any case, even if microscopic black holes were created at LHC, they would evaporate instantly, due to a phenomenon, Hawking radiation, which only rests on general relativity and quantum gravity, and is thus on much more solid ground than the very production of black holes. And in any case, even if black holes were created and they did not evaporate, they would escape the Earth without more than a few nuclear interactions. And in any case, even if scientists were wrong on all the previous counts, collisions like the ones LHC will produce are generated everywhere by cosmic rays, so the black holes generated inside the LHC would be nothing new under the sun.

For a more meaningful discussion of these issues, please visit this instructive post at backreaction.



1. Andrea Giammanco - April 14, 2008

Not such a wise idea, anyway, to write text in black over a dark background.

2. dorigo - April 14, 2008

True – and indeed, this is a draft. The final version is in white I think. Either way, some parts of the text won’t read well.


3. Fred - April 14, 2008

Nice to see your name closing the curtains. Someone should have let the students design the poster. It would have contained much more color and a refreshing attitude along the lines of the impressive CMS tracker, chamber and detectors which you have previously shown pictures of in related posts. Maybe a phrase to go along like: “Expose Yourself… to Darkness!” That old guy Galileo seems to be thinking the same thing in the upper left of the current poster.

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5. bookhling - April 17, 2008

The whole blackhole debate is more sensationalism than anything else, I think (of course, I’m personally hoping for a blackhole, for scientific reason).

At least this might be a good opportunity to teach basic physics to the general public. I spent the afternoon yesterday teaching middle school kids about Schwarzschild radius and Hawking radiation.They were thrilled to say the least.

6. Joe S. - April 17, 2008

No black holes created? Darn I guess I’ll pass. Great Post.

7. dorigo - April 17, 2008

Hi bookhling, of course you are right. And I am happy to hear there is somebody out there who is not deterred by the general reaction of suspiction to science divulgation…

It is indeed a good opportunity. Together with a few fellow physicists and bloggers, I am trying to put together an appeal to newspapers and magazines about being more responsible on discussing issues such as black holes production at LHC without including an expert opinion. Not a big shot opinion – the opinion of somebody with the hands on the turf.

Hi Joe, thank you – but yes, black holes are not something so easy to create in a lab. Especially since the smaller they are, the hotter, and the faster they evaporate!


8. dorigo - April 17, 2008

Fred, I agree – the design is rather lame. I was not responsible of it, and I could only steer the author towards using different colors, fonts, and putting the date in more evidence (in the first version, the date was almost unreadable!!).


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