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Why the LHC Won't Destroy the World
Posted by
CmdrTaco
on Mon Jun 23, 2008 08:33 AM
from the that'll-ruin-your-day dept.
from the that'll-ruin-your-day dept.
An anonymous reader writes "Most people are aware of the recent articles contending that the Large Hadron Collider at CERN might destroy the world. While most scientists have no such concerns, a recent preprint released to arxiv systematically dismantles the notion. The gist of the argument is this: Everything that will be created at the LHC is already being created by cosmic rays. If a black hole created by the LHC is interactive enough to destroy the world within the lifetime of the sun, similar black holes are already being created by cosmic rays. Such black holes would be stopped by dense cosmic objects (neutron stars and white dwarfs). A black hole stopped in one of these objects would eventually absorb it. We see sufficiently old neutron stars in the sky, thus any black hole that could be created at the LHC, even if it is stable, would have no effect on the earth on any meaningful timescale."
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Submission: Why the LHC won't destroy the world by Anonymous Coward
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Science: LHC Flips On Tomorrow 526 comments
BTJunkie writes "The Large Hadron Collider, the worlds most expensive science experiment, is set to be turned on tomorrow. We've discussed this multiple times already. A small group of people believe our world will be sucked into extinction (some have even sent death threats). The majority of us, however, won't be losing any sleep tonight."
Reader WillRobinson notes that CERN researchers declared the final synchronization test a success and says, "The first attempt to circulate a beam in the LHC will be made this Wednesday, Sept. 10 at the injection energy of 450 GeV (0.45 TeV). The start up time will be between (9:00 to 18:00 Zurich Time) (2:00 to 10:00 CDT) with live webcasts provided at webcast.cern.ch."
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Science: Black Holes From the LHC Could Last For Minutes 672 comments
KentuckyFC writes "There is absolutely, positively, definitely no chance of the LHC destroying the planet (or this way either) when it eventually switches on some time later this year. And yet a few niggling doubts are persuading some scientists to run through their figures again. One potential method of destruction is that the LHC will create tiny black holes that could swallow everything in their path, including the planet. Various scientists have said this will not happen because the black holes would decay before they could do any damage. But physicists who have re-run the calculations now say that the mini black holes produced by the LHC could last for seconds, possibly minutes. Of course, the real question is whether they decay faster than they can grow. The new calculations suggest that the decay mechanism should win over and that the catastrophic growth of a black hole from the LHC 'does not seem possible' (abstract). But shouldn't we require better assurance than that?"
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First (Score:5, Funny)
First particle?
Famous "last particle" (Score:5, Funny)
"We have an unintended event horizon."
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Re:Famous "last particle" (Score:5, Funny)
Although the parent is rated 'funny' currently, I can only imagine a new, really big lake in Switzerland soon, Lake Hadron.
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Re:Famous "last particle" (Score:5, Interesting)
What's this Either/Or crap? Just do both.
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Fools! (Score:5, Funny)
Don't they see that there used to be MORE neutron stars?
Re:Fools! (Score:5, Informative)
black holes emit nothing.
Ha!
http://en.wikipedia.org/wiki/Hawking_radiation [wikipedia.org]
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Re:Fools! (Score:5, Funny)
Has anyone mentioned that black holes emit Hawking radiation yet? Cause I'd like to clear that up, in case no one else caught that.
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Re:Fools! (Score:5, Insightful)
I see billions of golf ball size black holes crossing the galaxy, playing Pac-Man "the milky way edition".
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Re:Group collision mergers (Score:5, Insightful)
> Even if a black hole like particle was briefly formed and then hit by another particle
> or two or twenty, then what?
Then you would have a slightly larger nano-blackhole. It would still have such a tiny collision cross-section that it could orbit inside the Earth for a billion years without growing to perceptible size.
But the event you postulate is extremely improbable in any case because of that tiny collision cross-section.
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Re:Fools! (Score:5, Informative)
Cosmic rays travel through the Universe with enough energies to boil a cup of water (in one single proton). That's up to 100 000 000 times more energy than the LHC. Those particles collide with everything, at a rate of a few per square kilometer per millenium. It might seem small, but consider the size and lifetime of the Earth, the Moon, the Sun, etc; combined. Particles whose interactions with the atmosphere would have the same energy as the LHC's collisions hit us more than 100 times per day per square kilometer. Over the lifetime of the Earth, every event that can happen in 10 years of LHC operation would already have happened hundreds of thousands of times [arxiv.org] on the Earth alone. Since we're here, there's clearly no need to worry.
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Re:Fools! (Score:5, Informative)
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Hang on a minute (Score:5, Funny)
Even if they did manage to destroy the world, we'd all die so quickly there wouldn't be time to dish out any blame.
I can imagine the last words in the lab just before we all disappear into a singularity:
"Oops"
Re:Hang on a minute (Score:5, Funny)
Or "I'm hungry" or "This coffee is awful".
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Re:Hang on a minute (Score:5, Funny)
Or 'Hey, watch this'
*cue redneck throwing a firecracker into the path of the particle stream*
Cheers.
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CERN Coffee (Score:5, Informative)
You obviously haven't tasted CERN coffee - they have expresso machines and its generally very good. Much more likely is "This food is offal". I remember several times going to to the coop and the three dishes of the day were things like calf's head, tripe sausage and tongue...yummmm!
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Re:Hang on a minute (Score:5, Funny)
"Oops"
No, the world will end with a scientist uttering "Oh, sweet!"
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Re:Hang on a minute (Score:5, Insightful)
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Re:Hang on a minute (Score:5, Interesting)
Actually we wouldn't. The black hole would not be any heavier than the earth (the moon would continue to orbit it as if nothing had happened, and the black hole would happily circle around the sun). Since the earth's mass is not that impressive, the black hole would have to be tiny, so the area around it where the gravity would significantly bend the universe would also be quite small, making our painful (but swift) deaths rather unspectacular.
Yeah I know. 'WOOOOSH!'
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we are completely safe, thanks to me (Score:5, Funny)
I'm sorry, but you're completely forgetting about at least one mitigating factor. There's simply no way the earth can be destroyed, one side effect of which would be my untimely demise. Why? Because I've still got a balance on my Capital One visa card, and they will do anything, including changing the very fabric of space and time, in order to not miss out on that interest money. So, we're safe for a while yet.
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Re:Hang on a minute (Score:5, Informative)
Whatever small compass we shove the matter into, it'll have exactly the same amount of gravity before and after. If we happen to shove it into a tight enough space that it becomes a black hole, it will be spectacularly tiny. It'll only start to accrete matter as it interacts with it. And, it'll have to get close enough to do it.
Gravity being what it is, it seems far more likely that a black hole formed in the lab would get drawn to the Earth's center of gravity (just like everything else on Earth is) rather than causing the Earth's center of gravity to shift. Shifting the Earth's center of gravity dramatically toward the LHC would take way more energy than what we're putting into the particles at the LHC.
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Re:Hang on a minute (Score:5, Interesting)
It doesn't matter where the black hole is created. It, like all black holes, is infinitesmal in size and infinitely dense. It'll fall right to the center of the Earth as if all the matter in between wasn't even there. Also, having started out life with the mass of a few atoms, it's going to take a looooooooooong time for it to destroy the planet. Black holes don't "suck" matter in. They can only pull matter in with the force of their own gravity--which is going to be very very tiny.
It certainly won't shift the Earth's center of gravity appreciably.
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Re:Hang on a minute (Score:5, Informative)
Doubt away...
The Black Hole would be a very tiny mass at creation, so small that the difference between where the earth's center of mass was before and is after is insignificant.
(In effect the before state is equal to finding the gravitational center of the earth, minus the gravitational center of a bunch of electrons that are about to power the LHC, then finding the separate center of those electrons poured into the LHC, and comparing that to the after state - where we have to find the gravitational center of the rest of the earth, and the gravitational center of the mini black hole) The center of the rest of the earth doesn't change significantly in the before and after pictures, and the power put into the LHC wasn't enough to cause any noticible wobble before it was used, was it? So it's not going to cause a wobble afterwards.
Now, assuming a stable black hole, it is drawn towards the center of the earth by gravity. Repulsion by solid matter isn't enough to stop it. (Repulsion is an electromagnetic effect - the cloud of electrons around normal nuclei push and so keep matter from passing through other matter. The hole doesn't have a cloud of electrons, so it falls. It 'wants' to go into a narrow elliptical orbit around the earth's core. (It's not falling straight towards the core, because the spot where it formed on the earth's surface has sideways velocity from the earth's rotation). As the hole falls it eats stuff, but that means it also emits electromagnetic radiation as stuff falls in. This works out in the end as a kind of friction, so the hole slows in its orbit and spirals inward. By the time it is up to a few milligrams weight, it is in a tight little orbit around the earth's core, and we are all alive, waiting for it to gradually gain weight. (If the boffins have told us). This takes a year or so, with us not really noticing anything until the hole weighs kilotonnes, at which point the last twelve hours or thereabouts get very impressive and the earth goes bye-bye.
So yes, you end up with the moon peacefully orbiting the black hole as the hole orbits the sun, in orbits that are so close to the existing ones it would be a real challenge to find the differences.
Now, the side of the moon towards us got some interesting radiation exposures during the final few minutes, perhaps enough to melt crater walls and such. The effect of all that light from the final flash might conceivably be measurable, out in the 20th decimal place or so when someone measures the Moon's rotational velocity.
Fortunately, this is all based on the idea that a black hole barely bigger than a proton is somehow stable, which we doubt very much.
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Re:Hang on a minute (Score:5, Funny)
You know, it's funny. I was at the aquarium yesterday and for the finale of the dolphin show a dolphin did a double backwards somersault through a hoop whilst whistling the 'Star Spangled Banner.'
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Re:Hang on a minute (Score:5, Interesting)
Actually, it will take a while. The event horizon of the hole will be small; the interaction cross-section with ordinary matter in the Earth is tiny. So it will orbit the centre of the Earth, absorbing a few atoms on each pass, gradually increasing in mass.
We'll notice by the time it reaches the mass of, say, a decent-sized mountain. It will cause local tides. Volcanism. Earthquakes. We won't die of spaghettification; we'll die because something awful inside the earth is whipping up the mantle like a blancmange and shredding the whole crust.
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If he's wrong? (Score:5, Funny)
Re:If he's wrong? (Score:5, Funny)
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This article doesn't take everything into account (Score:5, Funny)
Re:This article doesn't take everything into accou (Score:5, Funny)
We will just sent sg1 in to take care of the aliens and then we just blame it on the homer simpson type people working there.
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Re:This article doesn't take everything into accou (Score:5, Funny)
Now, now, if you follow standard insertion procedure, everything will be fine. ... Although I will admit that the possibility of a resonance cascade scenario is extremely unlikely.
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Re:This article doesn't take everything into accou (Score:5, Funny)
Slashdot doesn't need to hear all this, they're highly trained professionals. We've assured the administrator that *nothing will go wrong*.
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Black holes vs. negative strangelets ? (Score:5, Interesting)
Wasn't the actual "danger" in question the creation of stable negative strangelets (which would gobble up regular matter through electrostatic attraction, not through gravity like a black hole) ?
But still, if there was such a thing, cosmic rays would have created one "naturally" by now.
Re:Black holes vs. negative strangelets ? (Score:5, Insightful)
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Re:Black holes vs. negative strangelets ? (Score:5, Funny)
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Re:Black holes vs. negative strangelets ? (Score:5, Funny)
The Tremendous Hadron Collider is more likely to create a black hole with the munchies.
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Re:Black holes vs. negative strangelets ? (Score:5, Funny)
Yes, but this can be counteracted via the usage of normalets, which are generated by anybody who doesn't read slashdot.
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But but but... (Score:5, Insightful)
"Science is the work of the devil!"
I believe the saying goes, don't let the facts get in the way of a good story. "Safe" doesn't sell National Geographic, let alone Wired.
"cosmic rays" argument is bogus (Score:4, Interesting)
Let me be quite clear that I don't think the LHC is likely to destroy the Earth.
However, the argument that what the LHC does is equivalent to collisions of cosmic rays with the atmosphere is bogus. The LHC's collisions between two particle streams with equal and opposite momentum could create things that are more or less at rest with respect to the Earth; a cosmic ray hitting the atmosphere carries momentum that will cause any resultant particles to move away from us very quickly.
Re:"cosmic rays" argument is bogus (Score:4, Interesting)
I think it's pretty unlikely that two particles are going to hit each other 100% square on and all that energy will somehow cancel out and the result will just dead stop and drop to the floor. The particles in the LHC are going to be colliding with so much energy that the results are most certainly going to be moving at a very high rate of speed, high enough that something like the Earth's gravity will hardly be noticeable to it.
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Re:"cosmic rays" argument is bogus (Score:4, Informative)
Hence the argument concerning neutron stars which would stop such a particle.
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When news makers will understand? (Score:5, Insightful)
Stopped black hole? (Score:4, Interesting)
My question (Score:5, Funny)
Review of the Safety of LHC Collisions (Score:5, Informative)
Why Is It (Score:5, Interesting)
Why is it that physicists on and in favor of this project (and those that are following this story) are even remotely surprised by the "Create a black hole, and destroy the world" rhetoric?
We've heard all the sensational "Black holes are the ultimate destructive force" commentary from Astronomers for decades seen all the cool Black hole animations, etceteras, ad nausium.
In my opinion, all the sensationalism surrounding the Black holes to start with was a ploy for funding. Now that same story line shows it's dark side, and people seemed surprised at the outcry and at overly dramatic fear of the LHC.
I'm not saying that sensationalizing science is a bad thing per se, just that people shouldn't be surprised when it bites them on the ass.
Re:Huh? (Score:5, Funny)
"In theory", posting to Slashdot is safe.
"In theory" you can't accidentally summon the elder gods by not limiting your .signature to 120 characters.
"In theory" posting more than twice within a ten minute limit won't create an imbalance of left-handed and right-handed electrons within the local ethernet causing anything up to and including total protonic reversal. (I bet you'd be kicking yourself for not buying cables with signal directional markings [slashdot.org] which could have prevented this problem.)
So, yes, "in theory" the world is safe from being destroyed by you. Today.
And "in theory" that makes me feel better.
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Re:Huh? (Score:5, Insightful)
Yes, in theory. Just as the sun will rise tomorrow "in theory." And if I repeatedly shoot someone in the head, they will die, "in theory." And reality exists, "in theory."
Provability only exists in mathematics. For everything else, from decisions about what to buy at the supermarket, to designs of scientific experiments, we humans must use mental models that rely upon fundamental assumptions about how the universe operates (e.g. that past experiences allow us to make meaningful predictions). In other words, every action we take must be informed by some sort of "theory." The question then becomes "how robust is this model/theory?", "how much can I trust the predictions?", "what is the range of the possible outcomes?", "what are the consequences of errors in the assumptions/model/theory?", and so on.
If you have a specific problem with one of the assumptions, logic, modeling, mathematics, data acquisition, or analysis, then point it out in detail. But saying, "that's just a theory" is not useful. Everything we do is based on theories.
After all, the opposite is also a theory: Not turning on the LHC won't cause the destruction of the Earth... in theory.
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Re:Huh? (Score:5, Insightful)
There are two opposing viewpoints on the matter.
On the one hand, we have particle physicists whose "theories" on the interaction of subatomic-scale matter is drawn from decades of research and experimentation.
On the other hand, we have people who know essentially no physics and seemingly assume that the people building the LHC must be as lost when it comes to science as they. They make the argument, "Well, we don't *really* know what's going to happen."
It's amazing that the latter are able to function, as crippled as they should be of the fear of uncertainty.
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How small are we talking about? (Score:5, Interesting)
Well, exactly how small black holes _are_ we talking about? Because it seems to me that the whole scare is due to a few people's not really understanding physics.
Gravity is actually the weakest force at a particle level. But ok, let's imagine a really really small gravity well.
Arguably the interesting thing about one would be, basically, "up to what distance can it gobble things up." In other words, the the Schwarzschild radius [wikipedia.org].
I'll use simplified version, which is: 3km for something weighing as much as our Sun, and it varies linearly with mass from there. Literally. For Something the size of Earth it would be 9mm, btw, but they won't collide particles weighing the same as _Earth_ there. If they did, I'd worry about _recoil_ before I worry about black holes.
So how big a black hole will they create there? Say, about the weight of two neutrons? _Three_ neutrons? Heck, let's be generous and smash a whole five neutrons together. Each neutron weighs 1.67492729x10^27 kg. So 5 of them is very approximately 8x10^-27 kg. The Sun weighs 1.9891×10^30 kg, let's say 2x10^30 kg.
So we get roughly 3km times 4x10^-57 km, or 4x10^-54 metres. That's the ridiculously infinitesimal size, up to which it could gobble matter. By comparison a helium atom has a radius of 31 picometres, or approx 3x10^-11 metres. Our black hole is about 10 to the 43'th power smaller than that. Write a zero, a dot, 42 more zeroes and a 1. That's how much smaller that black hole is than a helium atom.
To be absorbed by it, another particle would have to come that close to it, overcoming all other forces. Which become pretty damn strong when you try to get that close.
In effect, the _only_ way for that "black hole" to gobble any other particle, is for that other particle to be shot directly at it with an even bigger particle accelerator. With some incredible (and thanks to that guy Heisenberg, also pretty much impossible) accuracy. Otherwise, it will be bounced around by the other atoms, without ever getting close enough to one to actually absorb one and get bigger and meaner.
If that's the big threat to Earth, well, I've seen scarier kittens than that ;)
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Re:Do I have this Right? (Score:5, Informative)
Right? I'm not a physicist.
In short, you are correct. If you were to magically replace our Sun with a black hole of 1 solar mass, the gravitational pull would not change. There would be a whole lot of other stuff going on, but black holes don't magically increase the gravitational pull of a mass.
If I made a blackhole out of the amount of mass that the LHC is accelerating, and put it suspended in a sealed jar on my desk, I would only feel the gravitational pull of the mass that actually is the black hole. So, unless people are having difficulty with the gravitational pull of things on their desk, I wouldn't be too worried about it.
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Re:Broken link (Score:5, Funny)
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