You probably don't even hear it when it happens, Right?
August 2, 2008 12:42 PM   Subscribe

You know the large hadron collider? What happens if it kills us all?

I realize it is highly unlikely, but it has been mentioned that this thing has the potential to end all life on earth once they turn it on. What I'm wondering is, if that actually did happen, how would it play out? Would it be like the end of The Sopranos on a global scale, where all of the sudden someone flicks a switch and our collective Journey song stops playing in the middle and everything suddenly goes black? Or would it be a more gradual, drawn out process of decay, destruction, and general mayhem?
posted by spilon to Science & Nature (28 answers total) 23 users marked this as a favorite
There was a thread discussing exactly what would happen here. Apparently tiny black holes don't work all that quickly.
posted by Countess Elena at 12:48 PM on August 2, 2008

If it kills us all because we're living in a false vacuum, then death with arrive with a vacuum wave that destroys the universe as we know it at the speed of light. No warning.

On the upside, the possibility of a 'vacuum metastability event' led to what I consider the most awesome paragraph ever published in a scientific journal:
"The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in the new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it. However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some structures capable of knowing joy. This possibility has now been eliminated."

S. Coleman and F. De Luccia (1980). "Gravitational effects on and of vacuum decay". Physical Review D21: 3305.
posted by Jairus at 12:48 PM on August 2, 2008 [40 favorites]

I joked last night, upon seeing pictures, that this thing seemed like it might kill us all!

The Wikipedia page cites CERN as claiming it's completely safe, and that there's no basis for any of the concerns.

Although... If I spent billions of dollars building a 17-mile long device in my basement to blow up the world, I'd probably get some people to claim it was safe, too.

It sounds as if they're doing it in steps: when it's first fired up, they won't be colliding anything too powerful, but they'll gradually keep going, provided that the locals aren't vaporized.
posted by fogster at 12:56 PM on August 2, 2008 [1 favorite]

For an exploration on what happens if you change the mathematical (and therefore physical and chemical) basis of the universe, read the Fredrick Pohl Heechee novels (starts with Gateway, and you have to start at the beginning).
posted by nax at 1:05 PM on August 2, 2008

What happens if it kills us all?

John Keane wins $1,000 (assuming the Earth is destroyed along with all of us).
posted by mullacc at 1:11 PM on August 2, 2008

It's important to remember that the unique feature of the LHC isn't the energy of the collisions: it's the production of large numbers of high-energy collisions in a small volume. There is a finite density of particles flying through interplanetary space with much higher energies than the few TeV to be reached at the LHC. People have seen billion-TeV cosmic rays, but not very many because the earth's surface is mostly not covered with detector arrays and we have not been looking for very many decades.

There's a calculation that has been done, which is straightforward in principle but I haven't looked up the numbers. From the cosmic ray spectrum, figure out the rate of high-energy collisions with the moon. From the LHC's press releases, figure out the comparable number of collisions during its expected operational lifetime. Which is bigger? Let's just guess that the collision rates are the same (which would be a fantastic feat of engineering) and that the LHC will run for fifty years (likewise).

We have good evidence that the moon has not been converted to a stranglet or a black hole or any such thing in four billion years: people have gone there and come back, and they are not made of strange matter or black holes. We have similar evidence about several other solar system rocks, both those that have landed here and those that we have sent robots to look at. So if the collision rates are the same, then the odds of being destroyed are four billion to fifty against. You could probably get another factor of ten if you counted all the rocky/metallic bodies without atmospheres. If you don't think there is anything special about iron or other heavy nuclei, you can count the planets with atmospheres (but just their surface areas, rather than their masses or volumes).

So to answer your question: judging from the empirical evidence that LHC-type collisions occur regularly throughout the solar system, and that the solar system is made of ordinary matter, the process of decay, destruction, and general mayhem would be long and drawn out and it started a long time ago.

p.s. I am selling LHC Apocalypse Insurance, memail me for details, limited time offer, etc.
posted by fantabulous timewaster at 1:17 PM on August 2, 2008 [4 favorites]

presumably the growth is exponential and initially very slow. it's initially very slow because the black hole is tiny and it's exponenital because (i assume?) the rate of mass increase will be proportional to its mass, so the heavier it gets, the faster it gets heavier.

that means there'd be nothing noticeable for some time, then suddenly - blammo!

what i was wondering last night is whether there'd be time beforehand for people to realise it was going to happen from analysiing the lhc results. i have no idea about that, but i'd prefer not to know myself - i can't imagine the world would suddenly be a better place because of knowing.

although it would be "blammo" when viewed from an external frame, which for a black hole isn't necessarily anything like the same as what it's like if you're actually crossing the horizon. i vaguely remember examples where you could survive the horizon crossing - but i would guess that required rotation.

on preview - fantabulous timewaster seems to still be ignoring the rest frame argument. if these high energy particles did create a black hole it would zip away from us at huge speeds (conservation of momentum). what is special about the lhc is that it can produce these things almost at rest (because it effectively smashes two equally fast particles head on, and they come to a very violent halt), which means that they stay here, near earth.

apologies if i am flogging a dead horse and there's something obvious that makes this untrue - i honestly haven't seen anything that addresses it plausibly.
posted by not sure this is a good idea at 1:28 PM on August 2, 2008

By the way, I think the concept of a huge particle accelerator creating quantum black holes which eventually destroy the planet came from "Thrice upon a time". To which all I can really say is, it's just a story, you know.
posted by Class Goat at 1:49 PM on August 2, 2008

the *exact* same pre-apocalyptic nonsense was being kicked around back when the RHIC was starting up at brookhaven in 2000. BNL took it somewhat seriously and this report [pdf] was made, in which diaster scenarios are examined and evaluated, and i think is what fantabulous timewaster is referring to.

the money shot: "In conclusion, we find that any significant strangelet production in the target fragmentation region is effectively ruled out by the persistence of the Moon."

anyway, since you asked about what would happen, there's a pretty good doomsday scenario, written by one of the chief lunatics opponents of the LHC here :

"a negatively charged strangelet condenses out of the quark-gluon plasma with a half-life more than a nano-second (10-9 second). That's enough time for the strangelet to traverse the vacuum in the RHIC, penetrate the iron wall (being slowed to thermal velocity in the process) and mingle with the helium atoms in the super-conducting magnet cooling jacket.

Spontaneous fusion would take place and the strangelet would grow as it consumed helium nuclei, giving off large amounts of radiation. At some point it would grow so large that it would fall through the helium containment-wall (consuming every atom it encounters on the way), fall out of the device, and penetrate the concrete floor, tunneling down to the center of the Earth.

The result will be the eventual (a period of days or months) conversion of every atom in the Earth to become part of one massive hot strange-matter nucleus. The Moon and a set of artificial satellites will orbit a white-hot strange Earth only about 100 meters in diameter but with approximately the original mass of the Earth (some mass will be lost to radiated heat). Once the strangelet is created, no power on Earth can stop it."
posted by sergeant sandwich at 2:00 PM on August 2, 2008 [1 favorite]

Hi, n.s.t.i.a.g.i. I hadn't thought about the fact that any LHC micro black holes will be "cold" like that.

If high-energy cosmic rays strike the moon and make lightweight black holes with lots of momentum, most of those holes will have to travel through some thickness of rock to escape. Whether they get trapped or not depends on how they lose energy.

If the cross section for black holes to scatter off of matter is σ, and the straight-line trajectory through the moon has length R, we can treat the part of the moon traversed by the hole as a cylinder with volume σR. If the momentum of the black hole is 1011 GeV, that corresponds to a mass of a 10-12 kilogram. So if the cross section is big enough that a column of iron with volume σR has a mass comparable to a nanogram, then the rest frame of the whole interaction isn't that much different from the rest frame of the moon. But even for a nuclear-sized cross section, it isn't.

So, hmmm. Interesting.
posted by fantabulous timewaster at 2:12 PM on August 2, 2008

i can't find the document i read, which made a very detailed case, but their argument was that the cross section for these things was tiny and they would orbit the centre of mass of the earth for some time before starting to grow (which supports the idea that naturally produced black holes leave as long as they have escape velocity).

this wikipedia article has a pile of references (and helps clarify things a bit because people above are referring to different scenarios). they seem to imply some natually produced black holes would be cold (not yet followed the links).
posted by not sure this is a good idea at 2:32 PM on August 2, 2008

ah. so i should have read this report a lot earlier. the argument against natural events all escaping is that they are typically charged, so have a high cross-section and are slowed. it's a good report.
posted by not sure this is a good idea at 2:39 PM on August 2, 2008

and, reassuringly, the expected time scale for growth significantly exceeds my expected life span :)
posted by not sure this is a good idea at 2:40 PM on August 2, 2008

I remember reading a story when young about a lab creating a black hole type anomaly which acts like a leak, sucking in our atmosphere. The lab and a decent area around it are sucked in, and the concern is that it's going to strip the world of an atmosphere. From memory a guy saves the world by clamping two large steel hemispheres around it, sealing it off. So, you know, we could do that.
posted by tomble at 4:48 PM on August 2, 2008

This would have made an excellent FPP on MeFI.
posted by Neiltupper at 5:01 PM on August 2, 2008

yeah, I feel we could contain it for a while, in a vacuum (after it ate up all the air molecules), and then blast it into space. someone else's problem then.
posted by ouchitburns at 5:05 PM on August 2, 2008

There's a lot of mysticism about high tech, and especially about radiation. Much of that approaches paranoia.

Unfortunately, these paranoid mystics have money for lawyers.

It takes a lot of energy to reach the outer planets. For the Voyager probes, NASA allocated the money and mass to include booster rockets powerful enough to put the probes on an orbit to reach Jupiter, but the Cassini probe was a lot heavier and by that point NASA didn't have quite so much money to play with.

So though the goal was to reach Saturn, they used a series of gravitational encounters here in the inner system to gain enough energy to get there. The last of those fly-by's was of Earth itself.

Solar cells can't be used in the outer system; light from the sun isn't stong enough. Cassini carries quite a lot of plutonium 240 for a thermal generator to provide the electricity needed to keep it going. And there are people who have somehow gotten the idea that a microgram of plutonium is capable of destroying all life on the planet if released into the wild. (Never mind that the atmospheric tests in the 50's and 60's probably distributed upwards of a ton of the stuff into the atmosphere with negligible effect on the life and health of the biosphere.

So some jackass went to court and tried to get a court order to force NASA to abort the fly-by, on the grounds that it was too risky. What if Cassini struck the earth and burned up in the atmosphere, releasing all that awful plutonium? They asked the judge to force NASA to use steering fuel on Cassini to change its orbit so it wouldn't come close to the earth. Needless to say, that would have also meant that Cassini would not have reached Saturn, causing the entire mission to be a failure.

The case should have been dismissed immediately, but the judge did give this nut time to try to present some semblance of evidence for his fear. NASA had to send a lawyer to rebut.

Fortunately, the judge told the nut "no", and the fly-by happened according to plan. Cassini is now orbiting Saturn and sending back all sorts of wonderful data.

Nothing in life is completely risk-free. You can die in your sleep; thousands of people do every year. To ask for proof that a scientific experiment is completely risk-free, or that an engineering-project is completely risk-free, and to prevent them from going forward until they provide such proof, is to completely halt progress -- because it can't be done.

Which, for some people, is a feature and not a bug. There are people who think they can stop progress entirely, or at least wish they could.

There are always risks associated with every choice you make (including refusing to make a choice), but that doesn't mean that every conceivable risk is real. This one isn't. The LHC isn't going to destroy the planet.
posted by Class Goat at 5:19 PM on August 2, 2008 [3 favorites]

(Sorry, it was Plutonium 238, not Plutonium 240.)
posted by Class Goat at 5:20 PM on August 2, 2008

I wish I had the brain-power to understand advanced physics. Alas, I can't add anything of value here, other than to say that I think most people are misunderstanding the question. He's not asking whether or not annihilation of the universe is likely, he's asking if it DID happen, what would it be like? Instantaneous? Bit by bit?
posted by grumblebee at 6:23 PM on August 2, 2008

The trouble with the LHC is that if we knew what would happen when we turned it on, we wouldn't have needed to build it. So assurances of its safety can never be believed 100%.
posted by w0mbat at 6:58 PM on August 2, 2008

It should be added that, while cosmic rays have always pummeled earth and yet we still exist, the argument has been made that the hypothetical non-evaporating mini-blackholes will have a small momentum when generated at the LHC (since the center of mass energy of the interacting particles can be close to zero), whereas the momenta of cosmic ray blackholes is very large (since the cosmic ray has very large momentum and interacts with effectively motionless atmospheric matter, the momentum of the collision products will be large). So, the mini-blackholes could hypothetical be trapped by Earth gravitationally and slowly grow until they're dangerous. But this argument was also shown to be wrong (by a recent paper) since e.g. neutron stars (which are extremely dense) can capture even the very high momentum mini-blackholes, and yet even the neutron stars still exist.
posted by Sneutrino at 10:37 PM on August 2, 2008

Not wanting to derail, but I have a side question - does anyone know of any information, conjecture or idle speculation on what'll happen if some more prosaic disaster than mutant-world-eating-particles-from-beyond-the-dawn-of-time occurs at CERN?

I live only an hour down the road from it over the French border, so even something as damp squib like as a megaton yield accident could be of potential interest . . .
posted by protorp at 12:24 AM on August 3, 2008

Sneutrino, see the LHC Safety Assessment Group linked above by not sure this is a good idea. My silly estimate (also above) that the moon wouldn't contain fast stable mini black holes seems to correspond to the first data point in figure 3 of this preprint released two weeks ago. The argument seems to be that a mini black hole in neutral normal matter, which has equal numbers of protons and electrons, will preferentially absorb the heavier protons and acquire a charge, making the interaction stronger.

I have to admit that, as much evidence for neutron stars as I've seen, I wouldn't stake my life on their existence. (My taxpayer dollars, yes; my career, yes; my life, no.) But Hawking evaporation is a consequence of thermodynamics and the fact that gravitationally bound systems have a negative heat capacity; the fact that, in larger systems, general relativity gets the radiation rate correct is just a bonus. From a phenomenological point of view, Hawking radiation is on much firmer footing than things like event horizons and singularities. I will totally stake my life on thermodynamics.

protorp, the difference between a reactor or bomb and an accelerator is whether the reactions taking place are self-sustaining. If you lose control in a reactor, things start heating up faster. If you lose control in an accelerator, the beam just stops. The most dramatic things that would fail at LHC are probably the steering magnets, which might crunch into things if they suddenly heated up. Or the power substation could fail, which would be like an ordinary (non-nuclear) power plant accident. What's actually being accelerated and collided is ordinary stuff: hydrogen, gold, lead. Stuff that's near the beam will get some neutron activation, but not enough to make a self-sustaining nuclear reaction.

grumblebee: the evidence is that, if the LHC will trigger some apocalypse, it will take some time long relative to the age of the universe. Doesn't disregarding that break the guidelines?
posted by fantabulous timewaster at 1:44 AM on August 3, 2008

protorp: rest easy. accelerators aren't really capable of that sort of runaway meltdown catastrophe, unlike nuclear reactors, which is what it sounds like you have in mind.

fission reactors take fuel measured in tons -- radioactive heavy elements (uranium, plutonium, etc) -- and carry out a "controlled" chain reaction. without human intervention, the reaction rate would grow exponentially, but plant operators keep the rate in check. it's a delicate, knife-edge balance: basically a nuclear bomb being detonated very slowly, so the potential disaster scenario is scary.

a collider like the LHC takes a very very small number of protons and antiprotons, accelerates them to very high energy and smashes them together. (and i mean a small amount - assuming 15 years of running non-stop at design parameters, you're looking at worst-case 0.05 mg of protons altogether). being matter and antimatter, the proton and antiproton annihilate each other, with a few possible outcomes.

one is that the combined energy of the two particles is released as a very high energy photon, called gamma radiation. the other is that exotic, highly unstable particles are produced (this here is the whole point of the thing), which rather quickly decay into more prosaic things, typically more gamma rays. this is a really gross oversimplification of the physics, but whatever, it's somewhat besides the point.

anyway, the radiation produced in the collisions is really very bad for you, but it's what's called "prompt" radiation - if you turn the LHC off, the radiation source stops. (and there is a whole department at cern devoted to ensuring that the radiation stays underground when the machine is active, that nobody's down there when the beam is on, proper controls are in place, etc.)

radioactive elements can't be turned off, so their activity is what's called "residual" radiation, and it's what makes them really awful - they get in your body and cause cancer and mutations, and stay in the environment for many years. when the prompt radiation is absorbed in the walls of the vacuum chamber, it can in fact turn non-radioactive isotopes into radioactive ones.

but as long as you don't build your accelerator out of depleted uranium, this won't lead to any nuclear explosions. the typical result is that the parts of the accelerator that absorb the gamma rays become slightly radioactive themselves and have to be disposed of with other radioactive waste.

dust, water, paint and so on can also be activated, but the dangerosity is pretty material-dependent, and for low-mass elements the half lives are typically pretty short, so they can just be allowed to cool off somewhere usually. i cannot say what it's like at cern, but at accelerators in the US, any potential contamination of clothes and so on are very closely monitored.

anyway, that is mostly of concern only to the people who will be in direct contact with the beamline. the key points here are that there's no potential runaway mechanism, most of the radiation goes away when the machine turns off (and keeping the fucking thing running is a hassle all its own), no significant quantity of heavy nuclei, and typically very tight controls on any potentially contaminated material.

so i would say the risk for someone living an hour away is no more or less than that for someone living directly above it, and both being equivalent to someone living halfway around the world. of course, it's the realm of new physics and we can never know what will happen until it does, and all that blah blah blah, but given the cosmic ray arguments presented above, i wouldn't worry too much about it.
posted by sergeant sandwich at 1:51 AM on August 3, 2008 [1 favorite]

(and there is a whole department at cern devoted to ensuring that the radiation stays underground when the machine is active, that nobody's down there when the beam is on, proper controls are in place, etc.)

. . .

it's the realm of new physics and we can never know what will happen until it does, and all that blah blah blah,

And if, say, a fly gets through their nets . . . ?

But seriously, thank you sergeant sandwich / fantabulous timewaster for as comprehensively as possible putting my mind at rest!
posted by protorp at 2:42 AM on August 3, 2008

protorp, a story (possibly embellished):

When Lawrence was building the first cyclotrons at Berkeley in the 1930s, a junior researcher raised the question that the radiation might be dangerous. So an experiment was designed where they put a mouse in a cyclotron, ran it for a while, and then they would see how the mouse did afterwards.

When the cyclotron was opened, the mouse was dead. This was very sobering.

Some time later, the junior researcher came to Lawrence and said, "You know, the cyclotron runs in a vacuum. The mouse wasn't irradiated to death --- it asphyxiated."

Lawrence thought for a minute and said, "Don't tell anybody. I like them being careful."
posted by fantabulous timewaster at 3:36 AM on August 3, 2008

Best answer: to answer the original question (i was thinking about this in bed last night...):

if there were a tiny black hole at the earth's centre, and it could accumulate mass at a fast enough rate to be dangerous (which i think we generally agree is unlikely) then you wouldn't actually notice much on the surface of the earth at first.

that's because, inside the earth, the total mass wouldn't be changing. all that the black hole is doing is changing the distribution of the existing mass (making it more central). that doesn't change how things feel outside - so you wouldn't start to feel heavier, for example.

in fact, the best way to think about it (as far as i can tell) is to ask yourself what would happen if someone started vacuuming away the inside of the earth (with some magical cosmic vacuum cleaner) while keeping gravity the same.

i don't know enough geophysics to answer that well.

what i would like to happpen is that the inner iron core would be sucked up, but the outer mantle/crust would remain as a hollow ball. if that happened, you'd have a hollow ball of rock with a black hole in the middle and (almost) nothing would seem any different on the outside of the panet!

(this seems counter-intuitive given the "movie version" of huge black holes, but ours is a much smaller one - its gravitation effects are, as i said, identical to the earth it has eaten, as long as you aren't too close to it).

unfortunately i doubt that would happen (if it did, one of the few consequences would be the loss of the earth's magnetic field, i believe, which is related to the molten core; another is that volcanoes would stop errupting).

instead, i suppose the earth would crumple up. so you would have huge earthquakes, and the land would fall "down". the earth would look like a broken ping pong ball. and then continue to collapse inwards.

assuming you survived that, and were "travelling inwards" on some piece of land, only then would gravity start to feel stronger (because at that point you are getting closer to the black hole, which still contains all the mass of what used to be more uniformly distrobuted under the earth).

and then it would get very hot and very noisy and you would be swallowed up... :o)
posted by not sure this is a good idea at 6:52 AM on August 3, 2008

a different take on how the world might be saved.
posted by not sure this is a good idea at 5:46 AM on August 6, 2008

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