# Large Hadron Collider Safety Question

**URL:** <https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836>\
**Category:** Factual Questions\
**Created:** [September 9, 2008, 8:13pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836 "2008-09-09T20:13:18Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![George\_Kaplin](https://avatars.discourse-cdn.com/v4/letter/g/3e96dc/32.png) [@George\_Kaplin](https://boards.straightdope.com/u/George_Kaplin)\
**Post date:** [September 9, 2008, 8:13pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/1 "2008-09-09T20:13:18Z")

</div>

Yeah. I know. There are about a billion other threads on this. Bear with me, though, because there is ignorance to be fought here.

As I understand it, the LHC will fire particles towards eachother at nearly the speed of light.

Safety concerns have been dismissed with the ubiquitous rebuttal _"Cosmic rays slam into particles all the time, and, because they’re faster, give off way more energy than anything that can be made at LHC. Since cosmic rays don’t cause black holes/strangelets/vacuum bubbles/James Blunt/whatever, we can be reasonably sure LHC won’t either. Now CHILL THE FUCK OUT BEFORE WE KILL YOUR DOG_[sup]1[/sup]"

Anyway, I got to thinking about this and I realised something. Cosmic rays smash into objects which are, if not stationary, then at least moving far, far slower than they are, right? In the LHC, the particles are going to be smashing into each other at equivalent speeds. Wouldn’t this fact invalidate the comparison between particle collisions at LHC and particle collisions taking place in nature? Going back to High School Physics, I seem to remember that if two bodies smack into eachother, the resulting energy released is equal to the combined energy of each body squared. If two particles smack into eachother and _both_ are travelling at near light speed, would the resulting release of energy be dangerous? Or would it still pale in comparison with the energy released from Cosmic Rays?

Also, even assuming the answer to the last question was ‘Yes’, I worry about the unforseen risks of containing such an explosive force inside a laboratory. Is there any danger that a release of energy even comparable with that of a cosmic ray could have cataclysmic consequences because it’s on earth?

A fiver to the first guy to reply with a laconic ‘No’ and a rolleyes

[sup]1[/sup] [sub]Hawking, Rees et.al. ‘Hypothetical Vacuum Metastability Events And Shutting The Fuck Up’[/sub]

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**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\
**Post date:** [September 9, 2008, 8:32pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/2 "2008-09-09T20:32:06Z")

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No worries. Although the energies involved are large when measured at the atomic scale they are not much in real life terms. And cosmic rays still beat out the LHC handily.

> [@](#):
>
> On the night of October 15, 1991, the Fly’s Eye detected a proton with an energy of 3.2±0.9×1020 electron volts.[1,2] By comparison, the recently-canceled Superconducting Super Collider (SSC) would have accelerated protons to an energy of 20 TeV, or 2×1013 electron volts—ten million times less. The energy of the Oh My God particle seen by the Fly’s Eye is equivalent to 51 joules—enough to light a 40 watt light bulb for more than a second—equivalent, in the words of Utah physicist Pierre Sokolsky, to “a brick falling on your toe.” The particle’s energy is equivalent to an American baseball travelling fifty-five miles an hour.
> 
> SOURCE: [The Oh-My-God Particle](http://www.fourmilab.ch/documents/ohmygodpart.html/)

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**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\
**Post date:** [September 9, 2008, 8:48pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/3 "2008-09-09T20:48:59Z")

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Hmm. Let me tilt my monitor upwards… nope. Nada.

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**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\
**Post date:** [September 9, 2008, 9:17pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/4 "2008-09-09T21:17:47Z")

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> [@George\_Kaplin](#):
>
> Also, even assuming the answer to the last question was ‘Yes’, I worry about the unforseen risks of containing such an explosive force inside a laboratory. Is there any danger that a release of energy even comparable with that of a cosmic ray could have cataclysmic consequences because it’s on earth?
> 
> A fiver to the first guy to reply with a laconic ‘No’ and a rolleyes

How about, no, no 3.2±0.9×10[sup]20[/sup] times no? 😛

Honestly, this has been thoroughly covered in those billion other threads. The only reason two beams are smashed together is to get all the energy out of the system as possible. The amount of energy has been calculated and recalculated. It’s not like it’s going to be a surprise that there are two beams. We know that the energy is equivalent to a moth fart. What are you asking that hasn’t been answered a billion times?

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**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\
**Post date:** [September 9, 2008, 9:23pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/5 "2008-09-09T21:23:53Z")

</div>

> [@George\_Kaplin](#):
>
> Anyway, I got to thinking about this and I realised something. Cosmic rays smash into objects which are, if not stationary, then at least moving far, far slower than they are, right? In the LHC, the particles are going to be smashing into each other at equivalent speeds. Wouldn’t this fact invalidate the comparison between particle collisions at LHC and particle collisions taking place in nature?

There’s no fundamental difference between a collision occurring between two moving particles or a stationary and a moving one – it only looks that way because of the choice of reference frame. Remember, motion is relative, so you’re free in the choice of your inertial system in which to describe the collision.  
Take, for example, a car crash: two vehicles slamming into each other at 100km/h each is the same as one going 200km/h colliding with one that’s standing still – total kinetic energy remains the same since it’s not a vector quantity, unlike momentum.

So that’s all quite nice and dandy, but what if we leave our boring old everyday experience of v \<\< c, and enter the exciting world of high speeds, dilated time and bent rulers?  
Well, in the result above, what I’ve implicitly done is using a Galileo transformation to connect two inertial systems, one in which one of the cars it as rest, and one in which the centre of mass of the system is at rest. The same can be done with objects at relativistic speeds, only you can’t use a Galileo transformation since you’re not allowed to go faster than c. Luckily, there’s a transformation handy that obeys this speed limit, the Lorentz transformation. Applied to the addition of velocities, it yields v = [v[sub]1[/sub] + v[sub]2[/sub]]/[1 + (v[sub]1[/sub]v[sub]2[/sub]/c[sup]2[/sup])]. Thus, two particles zooming at each other at a speed of 0.99c is the same as one hitting a stationary one at approx. 0.99995c, not 1.98c as you’d naively expect from everyday experience.

[QUOTE=George Kaplin]  
Also, even assuming the answer to the last question was ‘Yes’, I worry about the unforseen risks of containing such an explosive force inside a laboratory. Is there any danger that a release of energy even comparable with that of a cosmic ray could have cataclysmic consequences because it’s on earth?  
[/QUOTE]

No. See, while there’s a lot of talk about ‘high energy collisions’ and things, the involved energies are actually really, really small – 7 TeV are about 1.1 \* 10[sup]-6[/sup] Joule, which is [not very much at all](http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)#10-9). It _is_ (somewhat) unusual to have that much energy crammed into such a small space, i.e. to have such a high energy density, but it’s not gonna blow up with any kind of macroscopically appreciable effect. (On preview, I see that I’ve been beaten to this part.)

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [September 9, 2008, 9:34pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/6 "2008-09-09T21:34:32Z")

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Actually, **George** has a point. Smashing two high-energy particles head-on is a lot more than twice as energetic than smashing one high-energy particle into a stationary particle.

To be precise, the center-of-mass energy release (which is what’s relevant here) for a head-on collision is just twice the energy of each particle. But for a high-energy particle hitting an identical stationary particle, the center-of-mass energy release is sqrt(2\*gamma + 2) \*m[sub]0[/sub]\*c[sup]2[/sup] .

The Oh-my-God particle (an extremely high-energy proton cosmic ray) had a gamma of about 3_10[sup]11[/sup] (we can neglect the +2), so when it struck another proton, the center-of-mass energy release was about 7.7_10[sup]5[/sup] times the mass of a proton. The mass of a proton is about .94 GeV, so the CoM energy of the Oh-my-God event was about 730 TeV. Each of the protons in the LHC will have an energy of about 1 TeV, so the collisions in the LHC will have about 2 TeV. So we’re closer to the Oh-my-God event than it may naively seem, but we’re still hundreds of times lower.

Of course, it should also be noted that cosmic rays sometimes collide with each other. I’m not going to run the numbers on that one without getting paid for it (there’s just too many variables to manage easily), but I think it’s probably safe to say that collision energies far higher than we’re able to produce are a routine event.

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<div class="post-metadata">

**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\
**Post date:** [September 9, 2008, 9:35pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/7 "2008-09-09T21:35:32Z")

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**Created by Opposites, as  
a Harmonic Cubic Form,  
with a God like Opposite  
Analytical Brain that can  
learn both sides of a God  
and True Creation, I am  
wiser than any single brain  
thinker who suppresses the  
analytical challenge to God.  
God is Death of Opposites**  
[right][– Dr. Gene Ray, Cubic and Wisest Human](http://timecube.com/)[/right]

Stranger

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<div class="post-metadata">

**Author:** ![ivan\_astikov](https://avatars.discourse-cdn.com/v4/letter/i/58f4c7/32.png) [@ivan\_astikov](https://boards.straightdope.com/u/ivan_astikov)\
**Post date:** [September 9, 2008, 9:43pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/8 "2008-09-09T21:43:16Z")

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This is the best bit.  
**Academic free speech is a damn lie. Try  
to discuss & debate Nature’s Time Cube  
and your evil teachers will not allow you.  
Ignorance of Time Cube dooms humans,  
inflicting their own created “word hell”.  
Educators are actually “evil word gods”,  
teaching commercial plunder of Nature.  
The damn bastards suppress free speech,  
by denying Time Cube debate discussion.  
Students MUST DEMAND free speech -  
for the greatest of all human discoveries:  
Nature’s Harmonic Simultaneous 4 Day  
Rotating Creation Principle of Cubicism.  
Educated stupid, you can’t know Truth.**  
Word.

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<div class="post-metadata">

**Author:** ![garygnu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garygnu/32/2924_2.png) [@garygnu](https://boards.straightdope.com/u/garygnu)\
**Post date:** [September 9, 2008, 10:02pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/9 "2008-09-09T22:02:41Z")

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[Has the Large Hadron Collider destroyed the world yet?](http://hasthelargehadroncolliderdestroyedtheworldyet.com/)

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<div class="post-metadata">

**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\
**Post date:** [September 9, 2008, 11:04pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/10 "2008-09-09T23:04:38Z")

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> [@Half\_Man\_Half\_Wit](#):
>
> Take, for example, a car crash: two vehicles slamming into each other at 100km/h each is the same as one going 200km/h colliding with one that’s standing still – total kinetic energy remains the same since it’s not a vector quantity, unlike momentum.

You’re wrong. In the first case total energy is 2\*(1/2_m_100^2) = 10000m. In the second case it is 1/2_m_200^2 = 20000m

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<div class="post-metadata">

**Author:** ![gonzomax](https://avatars.discourse-cdn.com/v4/letter/g/e8c25b/32.png) [@gonzomax](https://boards.straightdope.com/u/gonzomax)\
**Post date:** [September 9, 2008, 11:36pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/11 "2008-09-09T23:36:02Z")

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> [@garygnu](#):
>
> [Has the Large Hadron Collider destroyed the world yet?](http://hasthelargehadroncolliderdestroyedtheworldyet.com/)

Tomorrow morning, sleep well.

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<div class="post-metadata">

**Author:** ![groman](https://avatars.discourse-cdn.com/v4/letter/g/73ab20/32.png) [@groman](https://boards.straightdope.com/u/groman)\
**Post date:** [September 10, 2008, 12:13am UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/12 "2008-09-10T00:13:47Z")

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> [@Dog80](#):
>
> You’re wrong. In the first case total energy is 2\*(1/2_m_100^2) = 10000m. In the second case it is 1/2_m_200^2 = 20000m

For kinetic energy in relation to the stationery third-party observer, you are correct.

For kinetic energy in relation to one of the colliding bodies, the energy will be the same for both cases 1/2_m_200^2

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<div class="post-metadata">

**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\
**Post date:** [September 10, 2008, 12:22am UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/13 "2008-09-10T00:22:11Z")

</div>

> [@Dog80](#):
>
> You’re wrong. In the first case total energy is 2\*(1/2_m_100^2) = 10000m. In the second case it is 1/2_m_200^2 = 20000m

That’s right, of course, I brainfarted and misspoke; what I should have said is that the kinetic energy relative to the centre of mass is the same in all frames of reference, and that’s what matters – leaving aside real world messiness, if you collide two masses with identical speed, there won’t be any movement in your current frame of reference (CoM) after the collision, but in the rest frame of one of the masses, the collision product will be moving at the speed of the centre of mass pre-collision – bottom line being, your car won’t get any more trashed if you run it into a stationary car at 200km/h than it will be at 100km/h in a head-on collision with another car doing 100km/h.

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**Author:** ![Omegaman](https://avatars.discourse-cdn.com/v4/letter/o/e480ec/32.png) [@Omegaman](https://boards.straightdope.com/u/Omegaman)\
**Post date:** [September 10, 2008, 12:25am UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/14 "2008-09-10T00:25:50Z")

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I don’t see a problem. Soon, the whole world will find out what will happen. It _will_ happen. No use worrying about it.

Can anybody stop it? Ummm, No.

I wise older gentleman taught me this useful phrase.

“Fuck It! , I ain’t gonna worry bout’ it!”

He was from the south, God rest his soul.

**Stranger** explained it in detail once, but I don’t have the learning to comprehend it. Again, It _will_ happen.

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<div class="post-metadata">

**Author:** ![Suburban\_Plankton](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/suburban_plankton/32/219_2.png) [@Suburban\_Plankton](https://boards.straightdope.com/u/Suburban_Plankton)\
**Post date:** [September 10, 2008, 12:45am UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/15 "2008-09-10T00:45:35Z")

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> [@garygnu](#):
>
> [Has the Large Hadron Collider destroyed the world yet?](http://hasthelargehadroncolliderdestroyedtheworldyet.com/)

Great! Now I have to alternate between refreshing \*that \*site, and [this one](http://www.abevigoda.com/ffb.php)…  
F5…F5…F5…

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<div class="post-metadata">

**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\
**Post date:** [September 10, 2008, 4:29am UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/16 "2008-09-10T04:29:15Z")

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> [@Omegaman](#):
>
> **Stranger** explained it in detail once, but I don’t have the learning to comprehend it. Again, It _will_ happen.

I’m guessing you are talking about [post=9771943]this thread[/post] (to which a lot of people contributed valuable insight into). We can speak with 12 sigma confidence that turning on the the LHC is not going to result in the end of the world. It might result in some interesting results that will give us greater insight into the fundamental mechanics of the world, and any amount of money it might be taking away from feeding the Third World poor or curing cancer is lost in the tidal wave of money and effort thrown away in professional sports, mass marketing, McMansion housing developments, and other affronts to the modern intellect. The biggest tangible hazard is all of the bad science fiction it will probably spawn.

Stranger

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<div class="post-metadata">

**Author:** ![Small\_Clanger](https://avatars.discourse-cdn.com/v4/letter/s/9fc348/32.png) [@Small\_Clanger](https://boards.straightdope.com/u/Small_Clanger)\
**Post date:** [September 10, 2008, 9:31am UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/17 "2008-09-10T09:31:05Z")

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> [@Stranger\_On\_A\_Train](#):
>
> The biggest tangible hazard is all of the bad science fiction it will probably spawn.

Too late [Torchwood](http://www.bbc.co.uk/radio4/bigbang/torchwood.shtml)

OK, it’s not on until this afternoon, but their track record is. . . inconsistent.

I’ll see if I can stay up for [The Genuine Particle](http://www.bbc.co.uk/programmes/b00db0x7) later on.

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<div class="post-metadata">

**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\
**Post date:** [September 10, 2008, 12:33pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/18 "2008-09-10T12:33:16Z")

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> [@Half\_Man\_Half\_Wit](#):
>
> Applied to the addition of velocities, it yields v = [v[sub]1[/sub] + v[sub]2[/sub]]/[1 + (v[sub]1[/sub]v[sub]2[/sub]/c[sup]2[/sup])]. Thus, two particles zooming at each other at a speed of 0.99c is the same as one hitting a stationary one at approx. 0.99995c, not 1.98c as you’d naively expect from everyday experience.

I’m not trying to question how this applies to the LHC, but isn’t that slightly hand-wavy? I mean, it takes exponentially more energy to accelerate a particle close to the speed of light, right, because its mass increases? So a particle going at 0.99995c has lots more energy than one travelling at 0.99c - in fact, if 0.99995c is the “equivalent” of a head-on collision between two 0.99c particles, is it the case that the kinetic energy is still quadrupled, just as you’d expect when doubling the velocity at everyday speeds, even though the velocity isn’t doubled?

Or am I grossly oversimplifying?

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<div class="post-metadata">

**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\
**Post date:** [September 10, 2008, 1:21pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/19 "2008-09-10T13:21:16Z")

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> [@garygnu](#):
>
> [Has the Large Hadron Collider destroyed the world yet?](http://hasthelargehadroncolliderdestroyedtheworldyet.com/)

No, it [never had the chance.](http://qntm.org/?board)

> [@](#):
>
> It is our duty to inform you that as of 7:35:05am UTC on September 10, 2008, the Earth has been destroyed.
> 
> \< snip \>
> 
> Evidence is still being collated, but preliminary results suggest that the Earth was destroyed pre-emptively by scientists at the Large Hadron Collider at CERN, Geneva, Switzerland, before the commencement of their experiments to locate the Higgs Boson, as a precautionary measure to ensure that the experiment itself could not result in the destruction of the Earth.

See ? They DO care about how safe the Collider is !

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<div class="post-metadata">

**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\
**Post date:** [September 10, 2008, 4:28pm UTC](https://boards.straightdope.com/t/large-hadron-collider-safety-question/462836/20 "2008-09-10T16:28:53Z")

</div>

> [@Stranger\_On\_A\_Train](#):
>
> I’m guessing you are talking about [post=9771943]this thread[/post] (to which a lot of people contributed valuable insight into). We can speak with 12 sigma confidence that turning on the the LHC is not going to result in the end of the world. It might result in some interesting results that will give us greater insight into the fundamental mechanics of the world, and any amount of money it might be taking away from feeding the Third World poor or curing cancer is lost in the tidal wave of money and effort thrown away in professional sports, mass marketing, McMansion housing developments, and other affronts to the modern intellect. The biggest tangible hazard is all of the bad science fiction it will probably spawn.
> 
> Stranger

Isn’t that a double negative type argument, though?

“It’s ok to waste money on this, because we waste more money on other things.”

My logic fault light trips when I hear that kind of line.

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