Miscalculation Invalidates LHC Safety Assurances 684
KentuckyFC writes "In a truly frightening study, physicists at the University of Oxford have identified a massive miscalculation that makes the LHC safety assurances more or less invalid (abstract). The focus of their work is not the safety of particle accelerators per se but the chances of any particular scientific argument being wrong. 'If the probability estimate given by an argument is dwarfed by the chance that the argument itself is flawed, then the estimate is suspect,' say the team. That has serious implications for the LHC, which some people worry could generate black holes that will swallow the planet. Nobody at CERN has put a figure on the chances of the LHC destroying the planet. One study simply said: 'there is no risk of any significance whatsoever from such black holes.' The danger is that this thinking could be entirely flawed, but what are the chances of this? The Oxford team say that roughly one in a thousand scientific papers have to be withdrawn because of errors but generously suppose that in particle physics, the rate is one in 10,000."
Something here is flawed (Score:5, Informative)
and I don't think it's the assurance that the LHC won't produce black holes that swallow the earth. There reason the whole LHC black hole rubbish is dismissed out of hand is simply because we have already obvesrved particles colliding with much higher energies than the LHC can produce and they didn't form black holes. Where did we observe these collions - in earth atmosphere. We built the LHC so that we could study the collisions in a controlled manner not because they are of particularl high energy.
I call BS - RTFA - it's about probability, not LHC (Score:5, Informative)
~kulakovich
If it does happen (Score:2, Informative)
Re:Voodoo Science (Score:2, Informative)
They do, actually. That's how particle accelerators work. According to general relativity, energy is equivalent to matter, and matter can be created from the kinetic energy of rapidly moving particles.
Therefore, the demonstrated inaccuracy of your previous statement gives us all reason to adjust our faith in this proffered probability accordingly.
False claim (Score:4, Informative)
The LHC paper has been 'published'. It has been peer reviewed up the butt. It has not been withdrawn. It obviously then falls into the 'other' 999/1000. Like slashdot is fond of saying: there is nothing to see here, move along.
Why I'm not worried (Score:5, Informative)
The Pierre Auger Observatory (http://www.auger.org/observatory/ [auger.org]) records one 10^19 eV hit per km^2 a year, just on earth. If that hasn't turned up any major anomalies in our solar system or even in the major mass centers in our close vicinity over the billions of years it's been happening then I would like an explantion why.
Every day.... (Score:5, Informative)
Every single day the earth is bombarded with particles of far higher energy than those the LHC could ever come close to producing. We've observed cosmic rays with energies that are several orders of magnitude higher than the LHC can ever come close to producing. The Pierre-Auger project will probably reveal that we're hit by far more of them, and might even tell us where they're coming from. So if the LHC were capable of producing a world ending event, we already wouldn't be here. Sure, "scientists meddle with forces they don't understand" sells papers, (and let's face it, if we DID understand them, we wouldn't need to meddle) but we all do that. How many of you know exactly how the computer sitting on your desk works, down to the excitation states of silicon? Yet you still use them and don't worry about them causing the world to end, because you know that it just isn't possible. The same analysis works for the LHC.
Re:hubris (Score:5, Informative)
If I had seen what they were doing beforehand I would have said 5:1 in favor. That place was a hell-hole.
Among other things the reactors had no containment vessels, was designed so badly that it required core cooling even after a shutdown. The control rods were so poorly designed that the core reaction rate actually increased while they were being inserted. The operators were performing a power failure test (on a live reactor!) where the steam turbines were to be used to generate electricity for the coolant pumps as they spun down. A previous similar test conducted under better conditions failed miserably. This previous failure was swept under the rug because it would have delayed commissioning the plant, meaning the plant's constructors would not get bonuses.
This new test was also planned in secret, without approval of the Soviet nuclear regulatory board.
During the run-up to this insane test a problem with the Kiev grid forced a delay in the test plan; rather than scrub and reschedule the plan was conducted with an unprepared night shift. The engineer in charge of operation of the control rods that night was a new employee with only 3 months of experience in that role. One of the documents associated with this disaster reads:
"One operator rings another and asks: What shall I do? In the programme there are instructions of what to do, and then a lot of things are crossed out. His interlocutor thought for a while and then replied: Follow the crossed out instructions."
Re:So the fact that there's no published figure (Score:3, Informative)
Re:A simple reason (Score:5, Informative)
Except that even if the LHC did create a black hole, the effects on the earth or any people are basically nil. The amount of mass/energy that's going to be involved in the LHC is practically nothing compared to the black holes that astronomers are looking for out in space. If a black hole happened to be created in an LHC particle collision, it would be incredibly tiny. Smaller than an atom tiny.
A newer but reasonably well respected theory about black holes has them emitting "Hawking radiation", and one of the ways that this stuff works is that the smaller a black hole, the more quickly it radiates away its energy/mass, and a minuscule black hole like we're potentially talking about here would evaporate almost instantly. For more information about Hawking radiation, ask the internet.
Even if we assume that hawking radiation doesn't exist, and that black holes last forever, a minuscule black hole created by the LHC would not be particularly dangerous. First off, when you smash things together in an particle accelerator, the resulting particles usually end up moving very quickly. A black hole that happened to be created would likely be moving in a random direction at a speed well above escape velocity, and would quickly fly off into space and we'd never hear from it again.
But let's assume again that it just so works out that a black hole is created, doesn't evaporate, and it ends up with very little momentum, and just starts slowly drifting around inside the earth. The black hole would have very little mass, and it's gravity would be negligible, it wouldn't "suck" in matter. For it to absorb another particle, it would have to actually bump into it. It's important to understand how very tiny this black hole would be. The event horizon would be many times smaller than even the diameter of an atom. And although we generally consider matter to be reasonably solid and dense stuff, an atom is almost entirely empty space. The black hole could pass through billions and billions of atoms without actually hitting and absorbing a nucleus.
So worst case, we end up with an extremely tiny black hole hanging out around the center of the earth, and on rare occasions, happening to absorb a particle and increasing its mass a tiny bit. Perhaps many billions of years from now it will grow large enough that we might be able to detect it somehow, but it's more likely that the earth will have been destroyed by an expanding sun before then.
Re:Something here is flawed (Score:5, Informative)
Clarifications (Score:5, Informative)
As one of the authors of the paper in question, I'd like to point out that the headline and summary are very misleading. We have *not* identified any particular miscalculation and nor have we claimed to. Indeed, we are impressed by the recent safety report and agree that it is very unlikely that there will be a disaster.
The basic point of our paper is that what we really want to know is the chance of the disaster happening, but the reports give us the chance of it happening given a large number of physical assumptions. These probabilities are not the same, because there is a small but real chance that there is a flaw in these assumptions. This need not be due to any mistake on behalf of the physicists but may be like Lord Kelvin miscalculating the age of the Earth because nuclear fission and fusion were not yet known. Think of it this way: in a random sample of 1,000,000 cutting edge scientific articles that look as reliable as the LHC safety report, how many of them are likely to have flaws that invalidate their reasoning? This is especially pertinent as the safety report for the LHC's predecessor (the RHIC) failed to take into account anthropic considerations.
Of course even if the argument is flawed, we are still probably safe. We have indeed dealt with this point in the paper. The overall risk is very small, but larger than the raw calculations suggest, and non-negligible when there are 6.5 billion lives at stake. We thus urge caution and a reassessment of the safety of the LHC taking these considerations into account.
I encourage you all to read the actual article, which goes into many of these points in detail:
http://arxiv.org/pdf/0810.5515v1 [arxiv.org]
arXiv is not peer reviewed (Score:2, Informative)
Re:Voodoo Science (Score:4, Informative)
What the LHC does is slam hadrons -- large collections of quarks bound together by strong nuclear forces -- into other hadrons at high energy. The LHC uses the hadrons it does not because there is anything special about them but because it's somewhat easier to get the energies they want to study using the hadrons they choose. They also chose the energies they use for the collision for convenience more than anything special. Ideally, they want the most energetic range they can accurately control. If they could build a bigger collider, capable of higher energy collisions, they would, but these things are complicated, big, and expensive.
Cosmic rays are a mixture of fast particles, including hadrons of various sizes, traveling at very high speeds. Many cosmic rays are bare protons, the same as used in the LHC. The energy range of cosmic rays is wide, ranging to many more orders of magnitude higher than the LHC. A collision between a proton from space at 100TeV and a proton in an oxygen atom in the upper atmosphere of the earth is very similar to a proton-proton collision in the LHC, but much higher energy.
If I am interpreting a graph on Wikipedia correctly, cosmic rays with an energy of over 1000 TeV impact the Earth at a rate of about 1 per square meter per year. Given the size of the Earth, that's 14 million/second. So 14 million collisions hundreds of times more energetic than the LHC can do happen in the Earth's atmosphere every second. And there appears to be a power scaling going on. 10TeV cosmic rays are thousands of times more frequent than 1000TeV cosmic rays.
The difference, and why the LHC was built, is location. Looking at cosmic ray collisions tells us what the end result is going to be, but it doesn't tell us what happens partway through. If you look at a car crash on the side of the road, you know that the car got squished and the driver was injured. If you look at a car crash in a lab with cameras and crash dummies, you can tell that the driver hits the windshield before the crumplezones absorb all the energy.
The same sort of thing with the LHC. If the LHC will create Higgs Bosons, they are being created all the time in the upper atmosphere. But Higgs Bosons are expected to last an incredibly short amount of time, and all we see is what's left after they decay into other particles. We can't see cosmic ray collisions clearly enough to see if the decay particles come from Higgs or from other processes we understand well.
Re:In the words of Dr Brian Cox (Score:3, Informative)
Re:Voodoo posting (Score:4, Informative)
It could be as low as
Probability is not the same as maximum likelihood. Nor are either of them the same as knowing whether the event will actually happen or not. Probability is an estimate. Maximum likelihood is a worst-case estimate (in this case, where we define bad to be high probability). Knowing whether or not the thing actually happens is voodoo.
Re:Don't fear the hadron (Score:3, Informative)
To make a black hole out of a mass the size of the Earth, you need to pack it into a radius of about 9mm [wikipedia.org]. That's incredibly dense, even compared to all known metals. And for less massive blackholes, the required density increases; at the masses we're talking, the radius is miniscule. Black holes also tend to evaporate, with smaller black holes evaporating faster. So whether we are looking at the upper atmosphere or at the LHC, any blackholes created cannot swallow matter fast enough to survive, let alone grow.
Re:Are they good for anything? (Score:3, Informative)
From our perspective, the matter goes in. From the frame of the matter falling in, space-time is so warped that time starts to dilate really-really strongly as you approach a black hole.
Re:Uncertainty and certainty (Score:2, Informative)
This paper doesn't "prove" anything other than they can't present any real arguments against the demonstrations that the LHC is safe. So instead they're intent on poisoning the well with this bogus analysis of retractions.
Here's a question for all of you that take this article seriously: how many times, since the advent of modern science, has a scientific result which nearly every practicing scientist in the field has said is valid, turned out not to be? I'm pretty darned certain that the answer to that question is precisely zero.
The thing that people should be paying attention to is not the fact that these few arguments may be mistaken, but instead the fact that nobody who has training in high energy physics takes these claims anywhere remotely seriously. The fact remains that there are copious theoretical and observational reasons why there is just no conceivable way in which the LHC can be dangerous.
Just to present a rough illustration as to just how unfounded and ridiculous these fears are, they require that some very select hypothetical and extremely unlikely ideas in high energy physics be accurate, while at the same time requiring that well-supported and extremely likely arguments about black holes be false (Hawking Radiation), even though the hypothetical ideas that lead to black holes at the LHC require there to be Hawking radiation!
Then, of course, there are the oft-mentioned high-energy cosmic rays which strike the Earth's upper atmosphere at around a million times the energies the LHC will be testing. And if you're worried about the collisions at the LHC being stationary with respect to the Earth, don't be: the way these collisions work, it'd be extraordinarily rare for a product of those collisions to not have escape velocity. Furthermore the products of ultra high-energy cosmic ray collisions are usually going to be charged, and therefore experience copious amounts of friction and stop within the Earth (if they're stable).
And so when faced with these arguments, and even stronger ones regarding the stability of other objects we observe, the best the fear mongers can do is say, "But wait! Sometimes you guys turn out to be wrong!"
I'm sorry, but this kind of nonsense is just invalid, and should be ignored. Poisoning the well is a fallacy, after all.