A few newbie questions about the LHC.

[Perpendicular]

Hello, I'm new here, and I guess I should give a brief intro.I'm in high school, and I have some interest in physics.A lot of it, in fact.I signed up because the fear mongering over the LHC led me to seek some answers, and I guess this is as good a place as any.

Well, here goes:

1) What is the probability of a micro black hole being created at the LHC ?

2)I know that cosmic rays collide in even higher energy reactions than that at the LHC.But the anti-LHC people say that the MBHs formed from these reactions are thrown away into space, while the MBHs formed in the LHC are created at rest.Is this true, and if it is, does it make a difference? How exactly is the velocity determined?

3)What are the odds of strangelet formation in the Large Hadron Collider?

4)Are there any other probable dangers of the LHC ?

5)If a micro black hole is formed at the LHC, does it pose any significant danger to Earth?

 

[cragar]

all i know is that my physics teacher told us that we should not be worried about the LHC creating a black hole and sucking in the Earth and that we should be fine. But you will need someone else to answer to give you more technical details .

 

[IttyBittyBit]

1) Very dismally tiny.

2) That's ridiculous.

3) Again, very dismally tiny.

4) Nope, and none of the other 'dangers' people talk about are probable either.

5) No, it would evaporate almost instantly due to Hawking radiation.

 

[Perpendicular]

Could you please elaborate on 2).

 

[Lsos]

My theory, is that every black hole in the universe was caused by a civilization that reached this point of technology and created a black hole on accident.

:P

 

[humanino]

Could you please elaborate on 2).

If in doubt, I suggest you read the detailed account account available from the LHC. If you have difficulties finding it, please ask for a link.

The point zeroth is that black hole formation at LHC itself is quite unlikely. The first point is that it does not really make a difference : LHC "black holes" would not be created at rest, the collisions at those energies do not take place on the protons themselves but on their constituents, so the momentum is not balanced. Second point, they must evaporate, this is well established : in order for LHC to create black hole, one has to modify the theory in the sense that evaporation is more likely. Creation and destruction go hand in hand : if they are so easy to create that LHC can do so, their evaporation must also be faster. Third, even if they were seating around not evaporating, they would be so tiny that the rate at which they would absorb matter would be safe for the lifetime of the Earth.

Again, you should really read the detailed account.

Finally, you bold faced "probable" so let me comment : yes the LHC can destroy the Earth with a non-zero probability. But so can you as well. There is a non-zero probability that you destroy the Earth by sneezing. Thermodynamics tells us that this probability is so vanishingly small that we cannot rationally worry about it.

 

[Perpendicular]

Thanks, that's what I was looking for.

I read that MBH formation was more like 1/second but oh well, if they are harmless I guess it doesn't really matter.

Is this the report I should read?

http://lsag.web.cern.ch/lsag/LSAG-Report.pdf

 

[humanino]

Yes, this report.

I'd like to comment on "The point zeroth is that black hole formation at LHC itself is quite unlikely.". If one watched for instance Lisa Randall's lecture at CERN on the topic, she is pretty clear about it : she does not believe black holes will be produced at LHC. The reason it is important to have studied this possibility, is that black hole production would have a quite distinct signature, and in the unlikely event that quantum gravity shows up at the LHC, it would be a shame not to be ready to recognize it.

 

[blechman]

welcome to the forum Perpendicular!

i would also mention two points

(1) EVERY particle accelerator has had doomsday cults associated with it for the last 20 years (Fermilab had one, and so did Brookhaven) - they just never learn!

(2) a thing about black holes: real people (that is, particle physicists! ) got really excited about black holes being formed at the Tevatron (the Fermilab machine) in the late 1990s and early 2000s because of theories of "extra dimensions" - if there is a fifth dimension, and it is large, then black holes might be formed at these experiments and this would be a great way to look for evidence of these new dimensions. however, this idea has died down considerably over the last several years for many reasons. these are not "ordinary" black holes like the one Disney made a movie about! And there is no need to worry.