After all the unnecessary panic regarding the end of world stuffs after the protons start colliding at LHC, I have read a brief essay by Michael Peskin (SLAC) where he talks about how this dire possibility can be ruled out both theoretically as well as experimentally. He talks about the paper Physical Review D 78, 035009 where Steven Giddings(UCSB) and Michelangelo Mangano(CERN) have argued with explicit calculations that if LHC can produce such a black hole which can swallow the earth these kind of events would have astrophysical consequences in the past Universe. But we dont see any well known astrophysical objects swallowed by such dangerous black holes.
Peskin also points out the fact that although we keep on saying that any micro blackholes if produced in CERN would evaporate almost instantaneously by Hawking Radiation, there is no experimental evidence of Hawking Radiation so far. But the theoretical arguments behind Hawking radiation is so strong that we can't rule it out. Although there is a model by Unruh where black holes do not radiate, it is also constrained by the fact that it happens only at the cost of violating Lorentz invariance which can happen only at the Planck scale. Thus LHC which operates in TeV scale( 16 orders of magnitude below the Planck scale) is safe enough from these dangerous circumstances.
Peskin says,"If we ignore these strong theoretical arguments we could pursue another path. Huge numbers of high-energy cosmic rays have hit the earth over its lifetime. Thus we an argue, nature has already carried out the LHC experiments many times. If we are still here, the LHC must be safe."
He also talks about some scenerios where these arguments are insufficient. There are some "slippery" black holes which arise in the extra dimensional models which may creat a genunie problem. But in the paper mentioned above the authors have addressed this problem as well. You can at least see the Peskin's review article which doesnt need any subscription from Physical Review. The link is
http://physics.aps.org/articles/v1/14
Saturday, November 22, 2008
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2 comments:
Hello Debasish Borah,
Your article is thoughtful and logical, but I don't know if you account for the possible bias in the arguments presented by CERN.
What do you think of Professor of Law Dr. Eric E. Johnson's 5 part essay at:
http://prawfsblawg.blogs.com/prawfsblawg/2008/10/could-bad-judgi.html
JTankers,
LHCFacts.org
Hey thanks James.
Well I went through the page you mentioned. I certainly agree with the Prof Johnson's comments on the judicial process. But I dont have much idea how it could be done or how CERN is handling these etc etc. According to me these will complicate the things and may result in a delay of the experiment. But his points are well taken.
Well you are correct in saying that the arguments presented by CERN may be biased. CERN is big enough an organization to fool us. But the serious studies done by people who has nothing to do with CERN truly indicates the safety of the experiment. Although these calculations are too technical to convince a layman but thats what it is. We have only theoretical proof that its safe.
One more thing is that many well-known scientists e.g, Nima Arkani Hamed(IAS) have moved to CERN to participate in the LHC work. I hope these people will save us from being fooled around by CERN.
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