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Large Hadron Collider feedback needed

ben m said:
Wallmott, your question seems to assume that WW is thinking about the physics. He's not, he's reading the science section of the newspaper and projecting science-fiction fears onto it. If the paper reports that someone is building a 14 TeV collider, that's what he's afraid of. If the paper had reported that someone was building a 1 GeV muon collider, that would presumably be what he's afraid of.
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Weren´t there any physicists from germany or something? Rösser or something that also had some theorys about it? Or was that also just complete BS?
 
Wallmott said:
Weren´t there any physicists from germany or something? Rösser or something that also had some theorys about it? Or was that also just complete BS?
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There are theories that predict the LHC will produce micro "black holes". The threshold energy for that process is more or less totally unconstrained so long as it is at least 5-10 TeV. That's essentially because if it was lower we would already have noticed the effects at other colliders.

Of course in those theories these objects are totally harmless, as they just immediately evaporate.
 
Wallmott said:
Weren´t there any physicists from germany or something? Rösser or something that also had some theorys about it? Or was that also just complete BS?
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Sol is right, there are lots of theories predicting black hole production; there are zero theories predicting dangerous black hole production.

In all of these theories, there would not be a sharp "black holes start appearing when E > x", because of something called the proton form factor. There will be a gradually increasing probability of black hole production---as there is for any other particle---as the proton-proton energy goes up. Thresholds get a lot sharper at e+e- colliders.
 
sol invictus said:
More or less, yes. The Tevatron is a proton-anti proton collider, and the LHC is a proton-proton collider (but at considerably higher energy).
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Exactly. In collisions at LHC energies, protons and anti-protons behave pretty much the same. This is because the valence quarks aren't that important at 7 Tev - most of the collisions will be between partons from the "sea."
 
Is there not a difference between Cosmic rays and the LCH since in the LHC there will be collisions between two moving objects and the cosmic rays are hitting our planet that is standing still?

Or why is the naysayers saying that the argument of comsmic rays is not good enough for them?
 
How about strangelets then? Is it right that if one of the "dangerous strangelets" were formed they would become normal matter after it "ate" some of our matter because it would turn the negative strangelet into positive? Or something like that.


Sorry for asking all these stupid questions, im not any good at physics. Im just trying to calm my little brother down who is afraid of the LHC from what he heard from the media.
 
Wallmott said:
How about strangelets then? Is it right that if one of the "dangerous strangelets" were formed they would become normal matter after it "ate" some of our matter because it would turn the negative strangelet into positive? Or something like that.
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0) There is no evidence that strangelets are stable
a) There is no evidence or theory that RHIC should make strangelets. The closest anyone got was something called "strangeness distillation"; this distillation was discussed before RHIC turned on and before anyone knew how nuclear fireballs behaved. As far as I know, the idea was explicitly excluded by the data after RHIC turned on (no 1st order phase transition; no oddities at chemical freezeout; hydrodynamics).
b) Even if RHIC could have made strangelets, there is not even a conspiracy-theory-level prediction that it could make the (dangerous) negatively-charged strangelets.
c) Even if the laws of physics worked out such that RHIC were a strangelet-making machine, the LHC would be a *much worse* strangelet-making machine than RHIC.

Sorry for asking all these stupid questions, im not any good at physics. Im just trying to calm my little brother down who is afraid of the LHC from what he heard from the media.
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It may reassure your brother: the same cosmic-ray arguments that discredit the black-hole scenario also discredit the strangelet scenario.
 
Wallmott said:
Is there not a difference between Cosmic rays and the LCH since in the LHC there will be collisions between two moving objects and the cosmic rays are hitting our planet that is standing still?
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I assume this is because someone told you that if the collision products are standing still they could easily lead to a black hole which would (since it is stationary with respect to the Earth) destroy the planet. First off, if one knows anything about these collisions, then they know there is no guarantee that any particular collision product would be at rest in the lab frame - the overall momentum would cancel out, but the individual pieces could keep moving at high velocity. But if you assume those (supposedly dangerous) products are stationary in the lab, then we're all going to die, right?

Hooey.

Even assuming the worst-case scenario in such a situation, and assuming the such black holes are even generated in the first place, it's pretty much nothing to worry about. Here's why not.

Or why is the naysayers saying that the argument of comsmic rays is not good enough for them?
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Because they know nothing about physics and are desperate for attention, perhaps? :)
 
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Wallmott said:
Sorry for asking all these stupid questions, im not any good at physics. Im just trying to calm my little brother down who is afraid of the LHC from what he heard from the media.
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Tell him these kinds of experiments have already been conducted at the 1+ TeV level in the Fermilab's Tevatron for 20+ years now, and we're all still alive.
 
How close are the LHC energies to the energies seen with cosmic rays colliding with our atmosphere btw?
 
Humanzee said:
How close are the LHC energies to the energies seen with cosmic rays colliding with our atmosphere btw?
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The LHC is supposed to top out around 14 TeV on the collisions (two counter-rotating 7 TeV beams), while cosmic rays have been measured up to as much as 1020 eV in energy.

To put that in perspective, that puts naturally-occurring cosmic rays at energies as much as 107 - or 10,000,000 - times more energetic than the artificial events in the LHC.

By comparison, the LHC is a wuss.
 
MattusMaximus said:
Tell him these kinds of experiments have already been conducted at the 1+ TeV level in the Fermilab's Tevatron for 20+ years now, and we're all still alive.
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Why have we not heard any fear mongers talk about the Tevatron? I have just heard them talk about RHIC which is less powerfull, right? and now the last year the LHC.
 
Wallmott said:
Why have we not heard any fear mongers talk about the Tevatron? I have just heard them talk about RHIC which is less powerfull, right? and now the last year the LHC.
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Because they are obsessed with no particular reason, the same energies and higher occur in atomic explosions, hydrogen bombs, super nova and the like all the time. Cosmic rays suddenly they start their special pleading about why the higher energies of the cosmic rays do not count.

They want to be afraid, so they pick this one thing.
 
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Wallmott said:
Why have we not heard any fear mongers talk about the Tevatron? I have just heard them talk about RHIC which is less powerfull, right? and now the last year the LHC.
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I'm not sure. I don't spend much time attempting to figure out the thinking of crazies like that.
 
Its pretty wierd how everyone have been making such a big deal out of it, the media have made it seem that everyone is afraid of this and saying lets do it and see what happends but in reallity there is just one or two persons who are against it that are not even physicists and have no idea what they are talking about and everyone that knows what they are talking about knows that it is safe.

If im not wrong Wagner claims that he did find allot of stuff that the LHC crew did not think about in the saftey raport, but the reason that they were not in there was really because the scenarios were not possible so they were not even considered in the first place, and now they have gone to extreme legnth in the LHC saftey report just to show in every possible way that the fearmongers are wrong, am i right?

And that is what all the fuzz really has been about?
 
Wallmott said:
And that is what all the fuzz really has been about?
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Yes.

I will make one comment - not in defense of those cranks, but in general. Science is inherently risky, both because of immediate short-term dangers the experiment itself could pose, and because of unforseen long-term consequences.

When physicists were discovering quantum mechanics, they had no idea it would lead to atomic weapons 25 years later. When the first of those atomic bombs was about to be tested, there was a worry that it could ignite the atmosphere, starting a chain reaction that might end with all atmospheric oxygen consumed and the incineration or suffocation of all animal life. A relatively simple calculation showed this wouldn't happen. But could it have been wrong? Of course, that's always a possibility.

But the point one must always bear in mind is that inaction is often just as or more dangerous than action. The human race faces known and proven dangers - existential threats to our existence as a species. We cannot stop doing science, because if we do, we may well destroy ourselves (with climate change, with pollution, by running out of fossil fuels and clean water, etc.). Those are known, clear, and evident threats, many of which can only be solved in non-catastrophic ways by technological and scientific advances. To argue that some specific experiment should not be performed, it must be demonstrated that the risk of carrying it out exceeds such risks of not carrying it out, and more, by a margin and with a risk large enough to justify stopping it.

In my informed opinion, the LHC is a much less risky experiment than biological experiments with infectious diseases (to pick one of many examples). It's hard to estimate the risk of not performing these experiments, but it is clear that stopping the LHC - the largest experiment in human history - on the basis of these vague and uninformed fears would have a massive chilling effect on science across the board, potentially with drastic consequences.
 
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Holy heavens, thats a huge difference! Thanks Mattus. Are we still doing experiments with cosmic ray collisions? I assume the benefit to the LHC et.al. is that its a predictable and controlled invironment?
 
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