On hadron colliders, dark matter and black holes

[RPMiller]

That can be done a number of ways. I would give him transdimensional movement, and teleportation. Probably desolidification to allow him to pass through objects would be an option as well.

Perhaps I'll consider running a MapTool session of Hero some time.

[Steel General]

Something like Dr. Manhattan from the Watchman story?

[RPMiller]

Oh! Yes, I can see the similarity there for sure. Of course he was even more powerful than my suggestions, but yes good example.

[torstan]

Just went to an interesting talk by a Cern physicist who has spent the last year working solely on issues of safety of the LHC. Unsurprisingly the conclusion was that there is no chance that the LHC could destroy the world. However he made an interesting point that I had not appreciated. I was wrong when I said that cosmic ray data rules out any chance that the LHC processes could destroy the earth. The reason is that when a cosmic ray hits the atmosphere, the results of that collision are moving very fast. Think of it this way, a car hits another car head on, the two stop. A car hits another car at rest and after the collision the two cars move in the direction the first was travelling in. Now a cosmic ray is an example of the first situation, whereas the LHC is an example of the second. The amount of energy in both cases is the same - so the 'damage' to the entities involved is the same, but the remains of the collision are moving at different speeds in the two cases.

So why do we care how fast the remains are moving? A slow black hole is the same as a fast one right? Well, not quite. Take the worst case scenario where all we know is wrong and we can create stable neutral black holes in particle collisions then a black hole created by a cosmic ray collision would be moving so fast that it would exceed the escape velocity of the earth and go tearing off into space. It would pass through the earth and have no effect. However a black hole created at the LHC would be moving slowly and would gravitate to the centre of the earth and start to grow.

Now we need to find out whether such a thing could be possible. Now remember that all physics that we believe to govern black holes would have to be wrong for us to even begin to worry about such a scenario. However, we want an argument like the cosmic ray argument that doesn't rely on any assumptions at all.

The argument goes as follows:

High energy cosmic rays don't just hit earth, they hit all other things in the universe. So there are high energy collisions with energies greater than the LHC on all objects. Our problem with the earth is that a created black hole could theoretically pass straight through the earth and leave no trace. Therefore we need to find an object where a cosmic ray created black hole would stop rather than pass straight through. Such things exist. They are called neutron stars and are the densest objects in the universe. They are so dense that a black hole would certainly not pass straight through, but would stop instead. This would mean that neutron stars would be eaten by black holes.

Now we see a lot of neutron stars out there and we know how old they are. We can therefore out limits on the speed that any captured black hole would grow to a size at which it would be a danger. It turns out that even if all we know is wrong and collisions of these energies can create stable black holes then such black holes would have to grow so slowly that they would pose no threat to the earth until well after the sun had exploded - by many orders of magnitude.

It was very interesting to hear a long and detailed analysis of the risks from someone who has had to do the work and stand up and argue it in front of lawyers and politicians who are concerned about the risks. And the seminar was followed by pecan pie, which is always a plus.

[RPMiller]

Mmm... pie.... what? Oh, yea, that other stuff is great news!

[torstan]

So there have been a few developments recently that are worth mentioning. The full story of the CERN magnet failure has come to light. A large helium leak wrenched apart some very large and expensive pieces of machinery. The valves that were supposed to stop this just couldn't deal with the pressures involved. As I understand it, the plan is to replace the ones that were failing and improve the monitoring systems. This will take them through the summer and the LHC won't be starting up until September. They expect to get first collisions - still below the full energy of the machine - in late November, early December I think. They will then run through the winter which is more expensive as the electricity prices go up. However this will give them an opportunity to produce data people can get to work on, and start the all important work of getting the machine to full energy with a tightly focused beam.

In response to this, the tevatron - currently the highest energy collider in the world, and a US endeavour - said they hope to find the Higgs boson before the LHC can be competitive. The project manager for the LHC estimated that the tevatron had about 2 years before the data from the LHC swamps the total data the tevatron will have taken. That gives a pretty good estimate of the amount of time before the LHC produces interesting results. We may get hints and rumours before then though.

The other developments recently have been that the ATIC experiment that claimed in November to have seen dark matter might well be disproved by a new NASA satellite that's been taking data for the last 9 months. This is good news for me as it would mean my theories were not disproved. All good news on that front

Just thought I'd drop in a short update for those that have been keeping up with this thread. I'll mention other things as and when they pop up.

[Ascension]

I, for one, always like to hear the news on what you guys are doing. Fascinating stuff.

[Steel General]

I agree...even I don't understand the majority of it.

[torstan]

Well, as always, feel free to ask questions about the bits that I don't explain properly and I'll try to be clearer.

Oh, here's the picture from the BBC of the damage at one of the magnet junctions:



Note that this should all be in a straight line for the particles to travel around the ring. That helium leak really made a mess.

[Karro]

I'm curious, and maybe this was posted upthread and I missed it, what was your theory that may or may not be disproven based on whether or not ATIC had seen dark matter (and who is ATIC?)

Also, your previous post on the issue of why the earth won't be swallowed in a black hole made in the CERN labs is somewhat disappointing. Now we have to figure out how to spawn a post-apocalpytic setting all-over-again.