LHC Facts

[Someone] has raised the specter of unfounded fears. As a counselor she has reason to help people overcome fears. Let us put that in the moral balance with unfounded reassurances. Unfounded fears may give a few folks sleepless nights. Unfounded reassurances may kill 6.5 billion people, plus all of our hopes for the future. I suppose that one could weight probabilities to put that in balance, but it would take a very disparate weighting of probabilities.

The best solution is to found both our fears and our reassurances.

On the fear side:
I personally think that some folks overstate the probability of trouble. The theories that enable trouble seem to be a small subset of the set of all possible theories. However, there are respectable theories that enable trouble, so the space of the subset is hardly zero, or even the one in billions that collider advocates tout.

“Whitegoddess” wants to know how “it can all go wrong.” That is simple. A black hole is created at CERN, as predicted by some theories. It does not dissipate via Hawking radiation. This failure to dissipate is predicted by some physics papers. It them begins to slowly accrete particles. This accretion increases exponentially, with the increase in size of the black hole. In a few years (or a few billion, depending on the theory) it swallows Earth.

Now, some of the steps here are perhaps unlikely. I have not personally stopped planning for the future. However, a passenger airplane with these prospects would not be allowed to fly. Earth has 6.5 billion passengers. I think that a small amount of fear is not inappropriate here. Would Whitegoddess want to cure fear of tigers so that small children pet tigers in the zoo? But let us not have inappropriate fear! On some days the tigers are not hungry.

On the reassurance side:
If one is going to give reassurances, they must be grounded in safety factors. The safety factors that collider advocates claim have tended to erode. In 1999, the main safety factor was that black hole formation required energy beyond the reach of any collider. Then some string theorists began predicting creation of black holes at colliders. I concede that their theories are speculative, but since there are multiple published papers with more or less reasonable theories grounded in attractive conjecture, we have to assign at least a small probability to the possibility that they may be right. In 2003 the safety factor was Hawking radiation, which would dissipate the black holes that collider advocates now conceded might be created. (Indeed they looked forward to the opportunity to study black holes.) Then published papers pointed out problems with the fundamental theory behind Hawking radiation. This does not prove that Hawking radiation will not work, but again given published papers we must assign some reasonable probability to that possibility. Now an analogy between colliders and cosmic rays is supposed to demonstrate safety. Collider opponents have pointed out ways in which that analogy is inexact. Some folks seem to assume that collider opponents must be wrong simply because they are so wrongheaded as to oppose colliders, but Michelangelo Mangano, a member of CERN’s Large Hadron Collider Safety Analysis Group, at a recent talk at Berkeley, discussed problems with using “cosmic rays hitting the Earth” to rule out black holes and agreed with many of the points made by collider opponents.

If you want to say that colliders are safe, it seems morally imperative to have good reasons for saying so. Mangano’s group will issue a report soon. Let us hope that they have good safety factors this time. Meanwhile, folks keep claiming the old safety factors. The practice of claiming safety factors that those claiming should know are not good if they did a minimal literature review seems the moral equivalent of not checking one’s brakes when driving a truck loaded with plutonium (deadly if released in the atmosphere, a potential atom bomb if the plutonium shifts around.) Oh, but I am raising unfounded fears! The truck probably will not crash.

You ask good questions. You ask me to explain the sources for the following chain of dangerous events:

1) A black hole is created at CERN, as predicted by some theories.

The following two papers predict black holes at CERN. These were followed by dozens of other papers making the same prediction.

Savas Dimopoulos and Greg Landsberg, “Black holes at the Large Hadron Collider,” Physical Review Letters, 87(16) 161602, (2001).

Steven Giddings and Scott Thomas, “High energy colliders as black hole factories: the end of short-distance physics,” Physical Review D 65(5) (2002) 056010.

CERN itself considered the possibility of black hole production in the following paper. This paper predicts that black holes will dissipate by “thermal processes,” which in this context means Hawking radiation.

J.-P. Blaizot, J. Iliopoulos, J. Madsen, G.G. Ross, P. Sonderegger, and H.-J. Specht, “Study Of Potentially Dangerous Events During Heavy-Ion Collisions At The LHC: Report Of The LHC Safety Study Group” CERN, 2003.

2) The black hole does not dissipate via Hawking radiation. This failure to dissipate is predicted by some physics papers.

The following two papers question the fundamental theory behind Hawking radiation.

Adam D. Helfer, “Do black holes radiate?” Reports on Progress in Physics. Vol. 66 No. 6 (2003) pp. 943-1008.

William G. Unruh and Ralf Schützhold, “On the Universality of the Hawking Effect,” Physics Review D 71(2005) 024028.

3) The black hole then begins to slowly accrete particles. This accretion increases exponentially, with the increase in mass and size of the black hole. In a few years (or a few billion, depending on the theory) it swallows Earth.

You don’t want me to mention Roessler, but he has the only published work that I know of on this topic. Wouldn’t you be more comfortable if something this serious had been studied in more detail? I know of another Ph.D. physicist who also calculated that a collider-created black hole could eat earth in a few years, but his work has not been published. I had a posted debate with Landsberg where he made an offhand estimate that accretion would take a very long time, but that was not published in a peer-reviewed journal. Others also say that it would take a very long time. Until there is more peer reviewed work on this topic, we really don’t know what would happen, but at least some physicists calculate rapid accretion.

You also ask: “who are those theorists and how do they know ‘precisely’ what is going on at CERN? Do they or are they involved in the project? Are they as qualified as those who do?”

All of these theorists know the published design energy specifications for CERN collisions. Their predictions are based on those specifications. Unruh is a top specialist in quantum gravity. Landsberg has a top reputation. Helfer is thought to be pretty competent. I believe that all authors of papers I have cited are Ph.D. physicists.

However, you are asking the wrong question. The issue is not who is the most competent. The issue is whether any are total crackpots who we should dismiss out of hand. Any who are not total crackpots just might be correct. In the case of the safety of Earth, we do not want to dismiss a warning just because it was issued by the number three guy. In the case of the space shuttle challenger disaster, the engineer who warned of o-ring problems was not the lead engineer.

Are you familiar with the precautionary principle? The precautionary principle reverses the burden of proof in cases of scientific risk. Normally scientific publication requires good evidence that one’s theories are true. For example, the standard for publication is statistical significance, meaning loosely that the probability that the data shows the observed effect is at least 95 percent. (Some statisticians would quibble with this wording, but I have an MS in statistics, and I will defend it.) Now imagine applying this standard for proof to a risky activity. For example, the probability that the airplane will crash is only 50 percent. We haven’t proved that it will crash, so we will approve it to fly. Would you want to fly on that airplane? The precautionary principle reverses the burden of proof in cases of risk. Instead of requiring that risks be proved, the precautionary principle requires that those who propose a risky activity prove that it is safe. The precautionary principle is accepted by many risk specialists.

I bring up the precautionary principle because the spirit of your questions is to try to prove what is most likely to happen, in this case by consulting the most qualified specialists. In this case the thing that is most likely to happen is that CERN will turn out to be safe. The precautionary principle, on the other hand, tells us to worry about things that might not happen. Remember our risky airplane. It is most likely that it will not crash. It is most likely that the tiger is not hungry today. We are talking about possible destruction of Earth here. I think most rational people want that to be very unlikely to happen. If there is a serious reason to think it might happen, that is of concern, even if the serious reason comes from someone who is not the top scientist at CERN. In fact, CERN’s Chief Scientific Officer, Jos Engelen, was recently quoted in the New Yorker as instructing CERN scientists to say that the risk is zero. Should we simply salute and accept that? As a statistician I can tell you that a zero probability doesn’t make sense.

[Someone] asked me to respond to several arguments for collider safety. I am quite familiar with two of them. Two are sort of new. They may even be definitive. I appreciate the chance to think about them.

1. If the LHC can create micro black holes, cosmic rays have been doing it for years and years.
2. If these micro black holes are stable, we are awash in them because cosmic rays are producing them.

A cosmic ray hitting an earth particle and creating a black hole is an example of an inelastic collision. Another example is two billiard balls that hit and stick together. If one billiard ball is moving rapidly (the cosmic ray) and the other is stationary (the earth particle) the resulting black hole would retain the momentum of the cosmic ray. A cosmic ray that can create a black hole has a lot of momentum. The resulting black hole would be relativistic, that is, it would be moving at a substantial fraction of the speed of light. There are reasons to think micro black holes would interact with matter at rates not greatly exceeding the rates of neutrinos. Neutrinos can zip right through earth, and right through a star. Very few hit anything. Hitting something will stop a neutrino, but not a black hole. A black hole will only accrete the particle it hits, slow minutely, and keep right on going. A relativistic black hole would have to accrete thousands of particles to slow below escape velocity from earth. The binomial probability of this many accretions ever happening (given that a single accretion is improbable), even in trillions of cases during the billions of years of the existence of the earth, is vanishingly small.

On the other hand, black holes produced by colliders are produced by two particles moving in opposite directions. Their momenta cancel, so they can be moving at zero velocity. Actually the collision of consequence is the collision of the quarks, which have large and randomly directed energy. Quark energy would rarely cancel precisely, so most collider-created black holes would also be moving at faster than escape velocity from earth. However, a few would not be moving that fast. They would travel in orbits that repeatedly intersect earth. If they were slow enough, they would travel in orbits within the earth. Instead of zipping through earth in a few seconds, they would have forever to accrete.

Most of the matter in the galaxy is moving at astronomical, but not relativistic, velocity with respect to earth. Unless a cosmic ray collides with the minute fraction of matter that is moving at relativistic velocity, in exactly the opposite direction, resulting black holes would still be relativistic. Therefore only a minuscule fraction of natural cosmic-ray-created black holes in the entire galaxy would be moving at less than relativistic velocity with respect to earth. Slow black holes created in other galaxies would not have time to reach earth. Even if a slow micro black hole did approach the solar system, in most cases it would zip around the sun like a comet and return to deep space. Even if its orbit intersected earth, it would only spend a few minutes within earth, not enough to slow it down.

We call this the collider/cosmic ray analogy. It appears to be a false analogy.

Mangano from CERN’s Large Hadron Collider Safety Analysis Group discussed these problems with the analogy in his recent talk at Berkeley, and agreed with most of them.

3. Neutron stars are much more heavy and dense, and so would collect them faster, and inside of them the miniblack holes would accrete matter much faster.
4. Neutron stars are long lived, so these stable black holes are doing it no harm. (from this, we can actually set upper bounds on how fast black holes can possibly accrete matter in a worst case scenario). 5. This worst case scenario shows the LHC to be absolutely safe in a worst case scenario.

The neutron star argument is relatively new. I have not had time to review it completely, and I am neither a physicist nor an astronomer. We will have to work on this one. It may be the definitive safety factor that collider advocates (and all of us really) would love to see.

However, the argument has obvious problems. Neutrinos easily transit stars. Neutron stars are generally formed in supernovas. The core of the star becomes a neutron star, and the outer layers of the star are blown away. Therefore neutron stars have less mass than their parent stars. Therefore a line through a neutron star is less likely to intersect mass than a line through a star. Therefore a neutron star is less likely to stop a black hole than its parent star. Astronomers, am I right about this? And, as I say above, almost all natural black holes are traveling at relativistic speeds. Therefore they do not spend much time inside neutron stars.

The question above claims a bunch of facts. Do we know them for sure? Since my group needs to work on this issue, I would appreciate citations. It is not only a matter of appreciate. Proper scientific discussion requires citation or demonstration. If you don’t have citations you lose the argument. But for me right now, the citations are more important than the argument, and I would appreciate them.

Let us go through your claims.

Neutron stars are long lived. If I am right above, this is as expected. However, how do we know this fact? Suppose an occasional neutron star does capture a black hole and explode. (I am assuming that the core is accreted, and the resulting energy blows off the outer layers.) We see many cosmic ray bursts. How do we know some are not exploding neutron stars? There may be a reason, but again my model is not ruled out if all neutron stars are long lived.

We can set upper limits on how fast black holes can accrete mater. What are those limits? Does their calculation assume slow black holes? I would appreciate citations.

This worst case scenario shows the LHC to be absolutely safe in a worst case scenario. I really do hope that this is true. But it needs to be demonstrated.

One similar argument that was cited by Mangano in his recent presentation at Berkeley is contained in [Dar, De Rujula, Heinz,http://arxiv.org/abs/hep-ph/9910471] They discuss strangelets being swept up in star formation. This would take millions of years. Therefore their scenario is applicable only if strangelets are stable for long periods. But strangelets are thought to be unstable. They even say that strangelets are unstable in their own paper. This alone seems to completely refute their argument. They also talk of a star being entirely converted into a strange remnant, and assert that this would produce a signature that is more energetic than a typical supernova. In a typical supernova, an energetic process in the core blows off the outer layers. They do not explain why the outer layers would not be blown off in the case of a strangelet-conversion supernova. If this does happen, the signature would not be more energetic. It appears that they are wrong twice.

I have seen collider advocates … assume that anyone who questions colliders must be a nut. When they find a collider opponent who asks tough questions, some take their ball and go home.

[These] questions seem quite legitimate to me…

[The] most serious challenge is to Walter Wagner. I rise to defend him. I know the details. I donated the first money he ever got. I think he started his LHC Defense because of my donation.

Walter is the founding father of this field of thought. In 1999 he had a letter to the editor published in Scientific American, a letter that rather gently questioned whether the Relativistic Heavy Ion Collider, which was then being built at Brookhaven, might be dangerous. This started an earlier version of the present media flap. Brookhaven managed to turn off the flap by issuing a report by a group of physicists that considered black holes, strangelets, and transition to a lower vacuum state, and gave what appeared to be strong reasons not to worry. This successfully convinced most people and turned off the media flap. (Unfortunately, the reasons they gave not to worry did not age well. They said that black hole creation required energy beyond the reach of any collider. Now black hole production is predicted by some theories. They also said that a collection of strangelets would be electrically positive on its surface and therefore not attract normal matter. A recent physics paper says they can be electrically negative on their surface.)

Walter also tried a lawsuit at that time, but did not pursue it.

I learned about this issue in 2000. I read a popular article in Scientific American that predicted black hole production at colliders. This article said that Hawking radiation would immediately dissipate black holes. I knew a bit about Hawking radiation. One thing I knew about it is that it has never been seen–scientists have never gotten close enough to a black hole to be able to see it. As a statistician I had been working with low probability risk, so I was quite aware of the logic behind the precautionary principle. This seemed an important place to apply that logic.

I tried writing a letter to the editor. It was not published. I tried writing other things that were also not published. Editors had learned from the Brookhaven flap that there was no problem. Eventually I helped to set up two websites, http://www.risk-evaluation-forum.org and http://www.global-risk-sig.org. As I studied the history of the issue I learned about Walter’s letter. I tried to call him once, but he was out. A year or so later, I was impressed when he contacted me via email. He, I and a few others became part of a small group of collider opponents who exchanged email for a couple of years. As an indication of the level of the group, I was the only one who did not have some kind of doctorate–I only had three master’s degrees. One was a Ph.D. physicist, another a global risk expert. We tried a lot of things to try to put the collider issue back on the public agenda. We tried to publish papers, letters to the editor, open letters. We applied for grant funds. We wrote to top scientists. Nothing seemed to work. (Actually, I am not sure but have reason to believe that one of the top scientists we contacted helped convince CERN to set up their current Large Hadron Collider Safety Analysis Group.) Finally one day Walter spoke of filing another lawsuit. He said he would prefer to hire a lawyer, but could file the suit himself. However, even that would cost several thousand dollars in expenses. I immediately gave him $1,000, and another member of the group did likewise.

I have great respect for Walter. He has worked on the collider issue for years, and can write well about it. He is basically a nice guy. He can also be a bit flaky at times. I knew that he had some legal problems. If I could find, and pay for, a better lawyer, I would hire that lawyer. Walter also would prefer to hire another lawyer. It is not easy to find a lawyer to take this case. I have written to dozens of lawyers in Europe, and have yet to find one interested in taking the case there. Of course it would help if we had more money. Walter has been operating on a shoestring.

Whitegoddess disparages donating to the LHCdefense fund. Yes, at the moment I believe it goes directly into Walter’s pocket. He is operating on a shoestring. However I saw a letter he wrote to a potential donor in which he offered to set up a not-for-profit organization, if he could get help in setting up that organization.
I also would like to set up a not-for-profit organization. I have looked into the procedures and the costs. There are legal, accounting, and insurance costs. It can be done on a shoestring, but that takes work, and has problems. Bylaws and a board of directors are required. I would be a bit uncomfortable volunteering to work on that board if there were no officers and directors liability insurance. Doing it right costs thousands of dollars. If someone would like to donate those thousands (or donate the legal and accounting work) we can set up a not-for-profit organization to collect donations for this cause. I volunteer to work for that organization, if it is done right. By now setting up this organization may take too much time since LHC startup is due soon, although such an organization could work on similar issues in the future. Another possibility is to get an existing not-for-profit, tax exempt organization to administer the money. (This is done fairly frequently in the world of grant funding.) Does anyone know of an organization that would be willing to do this for this issue? It is quite possible that someone here happens to belong to such an organization. Otherwise, there is something to be said for trusting Walter. If one doesn’t trust Walter, I can suggest ways to spend money directly out of your own pocket, for specific things that would help.

I would like to have a better organization. To quote former defense secretary Rumsfeld, “You go to war with the army you’ve got, not the army you would like to have.” Actually, our “army” (an important principle is that we are all independent intellectuals) is getting better all the time. For example, I am impressed with this website. But we do not have time to wait for our group to become perfect, or to even to address many of the legitimate problems that critics might point out.

Professional Ethicists at Oxford discuss the issue:

April 15, 2008
Three arguments against turning the Large Hadron Collider on
In response to Anders Sandberg’s post on the Large Hadron Collider.

The physicists responses to worries about the risks posed by the LHC make it unclear whether they understand the moral issue. They may have the power, but they do not have the liberty to hazard the destruction of all present and future goodness. Nobody does.

Professor Frank Close of the University of Oxford has been quoted as saying that “The idea that it could cause the end of the world is ridiculous.” (here). Is it ridiculous because it is impossible, or because it is very unlikely? I don’t think he knows it is impossible, and being very unlikely is not sufficient to dismiss the risk. Yes, it’s very unlikely, but being very unlikely is not remotely unlikely enough and may be beside the point, as, I think, these three arguments demonstrate.

1st Argument.
1. A necessary condition on doing anything which might destroy all present and future goodness is that the expected value of doing it is positive

2. Setting g to be the total goodness (all present and future goodness) in the absence of running the LHC, x the factor by which running the LHC for a week increases goodness if it doesn’t bring total destruction, and p the chance of total destruction per week of running, then (gx–g) is the benefit that might be gained from a week’s running and the expected value is (1-p)(gx–g)-pg .

3. For the expected value of one week’s running of LHC to be positive we require (1-p)(gx–g)-pg >0 i.e. x > 1/(1-p).

4. Suppose p is one billionth, then x > 1.000000001….

5. So one week’s running of the LHC must increase total goodness by more than one billionth for the expected value to be positive.

6. But one week’s running of the LHC won’t increase total goodness by anything like one billionth.

7. Therefore the LHC should not be turned on.

2nd Argument
8. Suppose that a sufficient condition for it to be permissible to do something which might bring on the destruction of all present and future goodness is that the expected value of doing it is positive

9. Let g be the total goodness without doing that thing, x the factor by which doing it increases goodness if it doesn’t bring total destruction, and p the chance of total destruction. Then for the expected value to be positive requires x > 1/(1-p)

10. In that case it would be permissible to risk total goodness by doing something that risked total destruction with a chance of 50% provided it offered to increase total goodness by more than twice.

11. But not even doubling goodness justifies the risk of destroying all goodness.

12. Therefore positive expected value is not sufficient to risk the destruction of all present and future goodness.

3rd Argument
13. Avoidable risks of destruction of all present and future goodness should not be taken.

14. Turning on LHC is an avoidable risk of destruction of all present and future goodness.

15. Therefore it should not be turned on.