I have already pointed this out last weekend, but it is worth repeating, as I am getting quite a few extra visitors who are Googling for information about the LHC and black holes.
The activity at the LHC tomorrow is only to try to get a single beam right around the ring for the first time. There will be no collisions with other particles (well, unless the beam goes off course and smashes into something by accident. That would be big news, due to the delays it would cause in repairs.)
As LHC physicist Peter Steinberg explains above, even when the LHC gets two counter-rotating beams colliding (within a month or two) the first collisions will be at the lower energies that older particle colliders have already dealt with.
According to Peter, it will be a few months before it is cranked up to the higher levels of energy that are novel and could possibly create micro black holes or other particles. As he says, the death threats can be put on ice for a few months at least.
So: the world is definitely not ending tomorrow. You still have to pay your taxes.
As to my earlier post about the Rainer Plaga paper, I still have not received an email response from Dr Plaga. Given the heightened level of interest at the moment, it would give many people relief if he did acknowledge an error. If he doesn't accept that he made an error, then having some more independent physicists weigh in would help.
And here's something new to read about what the LHC might find: maybe not micro black holes, but "string balls", which may evaporate in a similar way to black holes anyway. The paper is about how to tell the difference.
I am curious as to whether there is any potential safety issue for them, if they don't behave quite as predicted. (Yes, I know, the same argument about stars and planets surviving cosmic rays would apply, but the same counter argument about the LHC creating slow moving objects would need to be considered.)
I also see there is a paper from August called "On the stability of black holes at LHC". It's a little hard to follow, but it would seem that they are arguing that it certain possibilities as to higher dimensions are true, the "behaviour" of the black holes created there may be "stable". I assume they mean that they won't disappear in a flash of Hawking Radiation, which has always been the main assumption of those doing the safety assessments on the LHC.
It's good that the LHC is not getting up to high energies just yet: it may allow sufficient time to get answers to these last minute concerns.
UPDATE: I have got a physicist to put into plain english the point that Mangano/Giddings were making in their rebuttal of Plaga:
Plaga is considering a warped extra dimensional scenario. In such models, there is a regime in which one is allowed to use the four dimensional quantities and laws, and a regime in which the phenomenology is described by the five dimensional laws (I describe this a little, in a simpler model, here). In their rebuttal, Giddings and Mangano point out that Plaga is applying four-dimensional formulae where they don’t apply, obtaining an incorrectly high result. This is perhaps the main clear problem.Mind you, Mark Trodden likes to call all people who raise safety issues "crackpots", which gets up my nose for reasons I have explained before, but he has performed a useful service here.
Now, if we can also deal with the LHC and naked singularities, string balls, and time loops, I would be feeling better.
3 comments:
Plaga and Rössler have both had their pathetic LHC-catastrophe papers annihilated by physicists that know what they are talking about.
You might be interested in some more info on those only two scientists to join the doomsday group. I just posted Large Hadron Collider: What's the Risk? on my blog. Plaga has had to retract results numerous times in the past.
I hope those naked singularities cover themselves up when children are around. There's a time and a place to be naked and singular, and that's called a 'Nudist Beach'.
Plaga has written a rejoinder to Giddings and Mangano's rebuttal. It was added as an appendix to a revised version of Plaga's first paper. He still stands by his original conclusion. The 4-D thing was a red herring, according to Plaga, because he didn't use the equation G&M accused of using.
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