Saturday, June 21, 2008

Black Holes at the LHC - The CERN Safety report

Earlier this year there has been a bit of confusion about potential dangers of switching on the Large Hadron Collider (LHC) at CERN. A lawsuit in Hawaii brought old fears back on the front pages of newspapers again, that the Earth may possibly be destroyed by strangelets, magnetic monopoles, instabilities of the vacuum, or black holes created in the high-energy proton-proton collisions planned at the LHC. We had discussed the actually non-existing danger posed by micro black holes in our posts Black Holes at the LHC - What can happen? and Black Holes at the LHC - again.

Yesterday, CERN has finally published the official report by the LHC Safety Assessment Group (LSAG). A CERN press release announces that the CERN Council looks forward to LHC start-up, and that the new report, updating a 2003 paper, incorporates recent experimental and observational data and confirms and strengthens the conclusion of the 2003 report that there is no cause for concern. Today's New York Times quotes from the abstract of the technical paper by Michelangelo Mangano, CERN, and Steven B. Giddings, UCSB, which is one of the pillar of the LSAG report that [...] indeed, conservative arguments based on detailed calculations and the best-available scientific knowledge, including solid astronomical data, conclude, from multiple perspectives, that there is no risk of any significance whatsoever from such black holes.

But just have a look at the report by yourself:

  • A summary of the LSAG report is available (as PDF file) in English, French, German, and Italian: The safety of the LHC / Le LHC peut être exploité en toute sécurité / Sicherheit am LHC / La sicurezza dell’LHC.

  • The actual report is the 15 pages Review of the Safety of LHC Collisions (PDF file) by John Ellis, Gian Giudice, Michelangelo Mangano, Igor Tkachev and Urs Wiedemann of the LHC Safety Assessment Group.

  • Technical details about strangelets and black holes can be found in the 11 pages Addendum on strangelets (PDF file) to the Review of the Safety of LHC Collisions, again by Ellis, Giudice, Mangano, Tkachev and Wiedemann, and in the 97 pages paper Astrophysical implications of hypothetical stable TeV-scale black holes by Steven B. Giddings and Michelangelo L. Mangano (available as preprint CERN-PH-TH/2008-025 (PDF file) and arXiv:0806.3381 [hep-ph]).

  • A review of the report and the two technical papers was prepared by the CERN Scientific Policy Committee (SPC) to provide [...] an independent opinion on the conclusions stated in those documents. SPC panel members Peter Braun-Munzinger, Matteo Cavalli-Sforza, Gerard ‘t Hooft, Bryan Webber and Fabio Zwirner came to the conclusion that they fully endorse the conclusions of the LSAG report: there is no basis for any concerns about the consequences of new particles or forms of matter that could possibly be produced at the LHC.
    This review is also available as a PDF file.


The main focus of the Giddings-Mangano paper lies on a detailed analysis of the possible creation of microscopic black holes by cosmic rays and at the LHC, and on a meticulous discussion of the potential growth mechanisms of these black holes. This analysis then allows to conclude, from the observed existence of very old and dense astronomical objects such as neutron stars, that the Earth is safe - at least from potential dangers posed by the LHC.




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35 comments:

Paul said...

I'm almost offended that they felt this required such a report.

My usual response to people when they tell me their fears in this regard is, "Do you really think that you've thought about black holes more than the theoretical physicists working on this project?"

CapitalistImperialistPig said...

Paul,

If you knew a bit more history, you might be more circumspect in your critique. Bad things do happen sometimes when new things are tried, and a careful analysis of the situation is almost never uncalled for.

Nor are those under the spell of a new idea likely to be the best judges of something that their dreams and careers may depend on.

Phil Warnell said...

Hi Bee,


“Speculations about microscopic black holes at the LHC refer to particles produced in the collisions of pairs of protons, each of which has an energy comparable to that of a mosquito in flight.”


- as taken from the synopsis of the report you cited


Well to put it into perspective it appears perhaps the only additional safety precaution required may be some insect repellant:-) Levity aside I hope this puts all reasonable concerns to rest such that they can get on with the work which many in your community and those interested others are anxiously and excitedly awaiting. So let the collisions begin.


Best,


Phil

Plato said...

The whole verification process on strangelets was necessary.

Phil Warnell said...

Hi Stefan and Bee,



“That black hole that was going to eat theEarth? Forget about it, and keep making the mortgage payments — those of you who still have them.”


-The “ New York Times” article cited


I’d be curious to know why in the above article I quoted (which you pointed to); the author DENNIS OVERBYE of the New York Times considered it necessary to hot link Earth? Was it he thought his readers might be uncertain what Earth is, was he trying not to have it confused with meaning soil or does he suppose his column is read by creatures who exist beyond out planet? :-)


Best,


Phil

Bee said...

Hi Paul, CIP,

I think it is good they wrote this report and from a legal point of view I can understand that some people found the issue was not appropriately addressed. CERN should have taken these concerns more seriously earlier then it wouldn't have come so far. In this particular situation I find the argument about the black hole scenario ridiculous, but that's because it's a topic I happen to have worked on and know something about. If I consider experiments in other fields where I couldn't tell exactly what the story is, I certainly would appreciate a similar report. The new CERN report I find extremely clearly written and I hope this will suffice and be the end of this catastrophe scenario. Best,

B.

Bee said...

Hi Phil,

I was actually very pleased to see the mosquito sentence. For reasons that I can't quite figure out one year ago or so there appeared in some newspaper article a completely wrong estimate saying that the energy per pp collision is that of two trucks colliding head on or so, which is many orders of magnitude off. People tend to forget that though 14 TeV is a lot for a particle collision, macroscopically it doesn't amount to much. Either way, this estimate unfortunately got picked up and I encountered it repeatedly in various pop-sci reports (English and German). I haven't checked the mosquito comparison (what's the weight of a mosquito btw?), but it sounds plausible. Best,

B.

Phil Warnell said...

Hi Bee,

“I haven't checked the mosquito comparison (what's the weight of a mosquito btw?), but it sounds plausible.”

Careful now for you omitted the momentum component for they referred to a “mosquito in flight”. So the question not only relates to its mass yet also how fast its going:-)

Also I hope you don’t feel that I take all this too lightly for I certainly don’t and yes for the reasons you stated the report was indeed required. However, it was done primarily for the benefit of those outside the community that felt that billions of dollars would have been spent on a machine that those responsible for had never considered its potential in terms of danger. In as I’m not of your community I can’t take this personally and yet if I were I certainly would. I believe more of those mentioned should be focused on the assorted paranoid fear mongers, media and governments who truly deserve this level of scrutiny.

Best,

Phil

Bee said...

Hi Phil,

Yes, I noticed they were talking about a mosquito in flight, but having seen mosquitoes flying I could estimate their speed. As to the weight however, I have no clue. Best,

B.

Phil Warnell said...

Hi Bee,

“Length varies but is rarely greater than 16 mm (0.6 inch)[3], and weight up to 2.5 mg (0.04 grain). A mosquito can fly for 1 to 4 hours continuously at up to 1–2 km/h[“

-As taken from Wikipedia

Now my only hope it that they weren’t actually referring to one of these Mosquitoes (actually that where made in Canada in WW!!) for that could have the whole thing heat up again:-)


Best,

Phil

Uncle Al said...

This issue is not properly addressed by degreed personnel tapping on electronic keyboards in air-conditioned vaults. The proper response is mobs with torches and pitchforks storming a cathedral then burning alive its priests in a public square.

Perform a calibration run at Re-ese Adbarat Kidiste Kidusan Dingel Maryam Ts’iyon in Axum, Ethiopia. 14°07′49″N 38°43′10″E. Test of faith!

QUASAR9 said...

Well Bee, I'm certainly sleep easier now.
I was still trying to figure out the information paradox.

I wonder if death is like falling into a microstate-blackhole, and what comes out the other side - hopefully there is some information loss, there are some memories/nightmares I'd be happy to lose forver - and there are others I like to linger on & playback in my mind.

CapitalistImperialistPig said...

Bee says,

In this particular situation I find the argument about the black hole scenario ridiculous, but that's because it's a topic I happen to have worked on and know something about.

Well of course you know something of the theory of black holes, though you don't really know much about the dynamics because nobody has ever observed a small black hole. Hawking's arguments seem persuasive, but there is zero experimental evidence. There isn't even any evidence for any component of the theory of TEV black holes. That said, I like the arguments of the report, and don't expect that the LHC will produce BH that swallow us next year.

CapitalistImperialistPig said...

Bee says,

In this particular situation I find the argument about the black hole scenario ridiculous, but that's because it's a topic I happen to have worked on and know something about.

Well of course you know something of the theory of black holes, though you don't really know much about the dynamics because nobody has ever observed a small black hole. Hawking's arguments seem persuasive, but there is zero experimental evidence. There isn't even any evidence for any component of the theory of TEV black holes. That said, I like the arguments of the report, and don't expect that the LHC will produce BH that swallow us next year.

Klaus said...

Hi,

Do you guys know the total mass (at rest) of those protons in one beam?

Bee said...

Klaus: The rest mass of the protons used for the LHC is the same as the rest mass of every other proton, roughly a GeV. If that wasn't your question then I didn't understand it. Best,

B.

Bee said...

Hi CIP,

That is correct and I never claimed I know things that nobody knows. Best,

B.

Bee said...

Hi Quasar,

Interesting question. Well, I don't know what death is like, but if you'd fall into a black hole this would be fatal in itself. Best,

B.

Stefan and Bee said...

Hi Klaus,

I guess you find the answers to your questions in the CERN faq: LHC- the guide (PDF file).

On page 30, you'll find a table with the important parameters for the LHC:

There are about 3000 proton bunches per beam, with a distance of about 10 metres in between, and with about 10¹¹ protons per bunch.

Hope that answers your question.

Cheers, Stefan

Bee said...

Ha, sorry for the misunderstanding ;-)

michaeldcassidy said...

Hyperlinking 'earth' was probably done automatically - by software.

changcho said...

My question is, what's with the lawsuit in Hawaii? Such a lawsuit has no jurisdiction over the starting up of the LHC, which is in Europe, no?

I am glad they've written up the CERN safety report, btw.

Bee said...

Hi Changcho,

Good question. I guess it's because this guy Wagner lives there? It indicates to me they did it mostly for the show-effect and not because they actually thought it would be necessary or good for something. Best,

B.

coraifeartaigh said...

Hi Bee, thanks for highlighting this, I didn't know the report was out.

It may seem daft to most physicists, but this type of public concern is not at all a trivial matter. I think the root of the matter is that certain people trust the word of scientists up to a given point (the existence of black holes), but no further (evaporation).

Sadly,the reaction of such people to a CERN safety report will not be that of you or I - far from respecting the eminence of the authors, the reaction will be 'of course CERN will find this'...

Best,
Cormac

Mike said...

Bee said:

" Good question. I guess it's because this guy Wagner lives there? "

I think they're suing Fermilab because they supplied some magnets... but I've heard it's only because they couldn't find a lawyer in Europe to take on their case :P

Anonymous said...

As much as I am sure everyone involved with the LHC at CERN deserves the utmost in respect for their scientific achievement, I ask if they have taken into account the fact that nothing, absolutely nothing is 100 percent certain in this world.

I also know that technology can be ahead of our ability to fully understand the long term consequences of our actions.

As I understand it, a recreation of the moment of creation is the ultimate goal. I suppose saying the elements are so tiny, that it is safe, may make sense to you, but how big were the elements in the original bang? Same size? My simple mind wonders that it won't start the process over... and where does that leave what is already here?

While all of your work is based upon theory, we happen to live in a world that often defies all theories.

A quote from Cern's own bulletin (http://cdsweb.cern.ch/journal/article?name=CERNBulletin&issue=24/2008&number=1&category=News%20Articles&ln=en) explains how they have had to disarm safety measures to proceed to this point already. "Paul Collier, Head of the Operations Group, was satisfied with how the day went, and explains the delays: "Everything went to plan in the sense that we are more or less on time for our programme. We had some significant difficulties. For example, some of the elements that are there for safety were in a position where they were locked and they had to be released before we could withdraw them in order to send the beam.""

I have been searching for further information since becoming aware of the LHC in April, and no update, schedule or information was released anywhere on the web for months, suddenly all is well?

I think there is too much money invested to turn back now, because in the real world, money pretty much motivates everything.

I have a feeling, if I could be standing at CERN to see the big moment, there would be lots of fingers crossed behind backs wishing for it to be ok (including mine) on the "Red Button Day." When is that, by the way?

Bee said...

Hi Anonymous,

As much as I am sure everyone involved with the LHC at CERN deserves the utmost in respect for their scientific achievement, I ask if they have taken into account the fact that nothing, absolutely nothing is 100 percent certain in this world.

Everybody knows that and the people working at CERN are no exception to this. If you cross the street it is also not certain you will ever reach the other side alive. If it was merely the statement nothing is ever 100% certain in this world that we would use as a guide we could never do anything.

As I understand it, a recreation of the moment of creation is the ultimate goal.

This is a very popular advertisement and also a very misleading one. The LHC pp collisions will not recreate anything similar to the 'moment of creation'. In these collisions one does not produce some kind of intermediate matter state with high density in any meaningful way. It is predominantly scattering processes. In the collisions of heavy ions one comes much closer to that, but also here the state only exists for a very short time and expands very rapidly.

For all I can say, the idea to 'recreate the early universe' isn't something that people working on that stuff take too literally. What is the question instead is, as you probably know, will we find the Higgs? Will we confirm the Standard Model or find something new? Can we learn something about the QGP? And so on. Pretty solid particle physics questions that are asked here. Besides this, if there was such a 'moment of creation' the energies would have been much higher, so the only statement that can be made is that one gets closer than we've ever been.

I think there is too much money invested to turn back now, because in the real world, money pretty much motivates everything.

Most of the people who work in academia are not motivated by money. You don't get rich if you chose this option, and if you want to make money there are usually plenty of better choices (e.g. banks/consulting) where physicists can get much better paid jobs. I have no idea where this decay of values comes from that makes people believe money is everything that matters. Just look around and you will notice that it is just not true.

I have a feeling, if I could be standing at CERN to see the big moment, there would be lots of fingers crossed behind backs wishing for it to be ok (including mine) on the "Red Button Day." When is that, by the way?

Don't know, I think some time late October. I too would guess many people at CERN will be nervous, but not because they are afraid a black hole will be created and swallow the earth. It is a hugely complex project, all pieces will have to work together perfectly. As with every project, accidents are possible, mistakes can happen and we all hope it will go well without any problems - but nothing is every 100% certain. Best,

B.

Quantum_Ranger said...

Is it "fact", tachyon :
http://en.wikipedia.org/wiki/Tachyon dispersion should start appearing locally "before" the LHC smashes particles together in real time?

PS could this be evidence:http://www.thesun.co.uk/sol/homepage/news/ufos/article1347649.ece

Anonymous said...

Wagner's lawsuit is completely bogus, and should be dealt a peremptory dismissal as a purely theatrical exercise in self-advertisement. However, let us not forget two things: (1) when the Trinity test was about to take place, respected scientists such as Fermi and Oppenheimer were taking bets on whether the bomb would ignite the atmosphere and destroy the world and (2) Castle Bravo had a planned yiled of about 5MT but the weapons designers overlooked a particularly energetic Li nuclear reaction and the resultant detonation went off at 15 MT. Well, I suppose we've learned since then.

Anonymous said...

Hi,

I was reading alot about the LHC recently and its had me pretty worried.( i know i shouldnt be ) but i suppose im that sort of person.Anyway i wanted to say thanks this seems to be the only page iv found with honest answers to these questions. I dont mean to offend anyone here but i hope you can see how someone with very little understanding of the LHC or physics could get worked up so easily with this.

Observer said...

From the 'other CERN scholars' report: "

Section 4 reviews the highly hypothetical production of neutral stable black
holes, and the possibility that these black holes could be trapped inside the Earth. While
such a possibility is dismissed by most of the experts, it is conceivable, and it could have
potentially dangerous consequences if these highly hypothetical, neutral, stable
microscopic black holes could accrete matter on Earth on time scales shorter than the
natural lifetime of the solar system. For this to occur, a number of increasingly unlikely
conditions should be satisfied: 1) the fundamental scale of gravity should be within the
LHC energy range, possible only if extra spatial dimensions with very peculiar
properties do exist;"

What's interesting about this is that I know that one of the other CERN scholars, Bryan Webber, is designing an LHC experiment to create an extra-spatial 'fifth' dimension. His 'fifth' dimension, though, would not have the 'very peculiar properties' they mention that would be necessary for a micro-black hole to grow rapidly.

I think we'll all survive the LHC beginning operation. ;-)

Anonymous said...

I dont know much and not good with numbers
black hole =inf. density (no mater the size)
or maybe i got it wrong and you dont have to read more
so 2 scenarios if i got it right
1 they are not going to produce a black hole
2 they will and density is relevant to weight/gravity so we die no mater how small black hole is

ps i think its to early for human kind to test stuff like that
they should cure cancer and A.I.D.s first (i know there is no money in cures only in problems )

ps2 maybe i dont have the right to speak in here but its my thought (simplify sometimes work better than analysis)
sorry for my bad English. bb :)

Keith said...

I would like this "black hole" issue explained a little. The first question is whether a collision btween two (or more?) protons considering their relativstic masses and velocities is capable of producing a black hole (for my layman's view this equates with asking whether there is anough pressure available to squeeze the masses into a volume small enough to have the requisite density).

Given that the answer to that is 'yes' then the next question is what would be the characteristics of such an object. What would be its speeed, direction and radius of the horizon? And given those characteriatics, what would be the likely fate if say its direction was towards the centre of the Earth would it likely collide with nuclei (or would it be too small), would it evaporate, would it act like a neutrino and interact with virtually nothing before exiting the Earth? In other words - are BHs going to be created and if they are then why will it be 'ok'.

Thanks

Bee said...

Keith,

If you had read this post, any of the above mentioned posts, or any of the extensive literature on the subject you could have easily answered your questions. Excuse me, but I find it extremely annoying to answer the same questions over and over again to people who pretend to have an interest but don't even bother to read a complete paragraph.

Please check our posts Micro black holes for general question about these objects, Black Holes at the LHC - What can happen? for the question what would happen if they'd go through the earth (which is also discussed in the report that is content of this post) and Black Holes at the LHC - again for a summary of the non-existent risk.

Pressure is a quantity that makes sense only for a large number of particles such as in a gas. It is meaningless to speak of a pressure in a collision of two particles.

These black holes could be produced only if the world had additional compactified extra dimensions, which is a very speculative and so far completely unconfirmed scenario. Within the well confirmed theory of standard General Relativity, the LHC can not, I repeat, can not produce any black holes whatsoever.

Best,

B.

Bee said...

Anonymous,

You indeed got it completely wrong. It doesn't take infinite density to produce a black hole, and producing one would not mean we would die all anyhow. So how about you breath deeply, in, out, and calm down again because the earth will not end tomorrow. Besides this, I recommend reading some of the relevant literature before coming to completely nonsensical conclusions. Best,

B.