Hoo boy. Perhaps I should have cracked wise about a subject that does seem to worry some people.
In all seriousness, then:
So-called "cosmic rays
," 90% of them anyway, are highly energetic protons coming from natural sources elsewhere in the universe. Every single day, they collide with protons and other particles in our own planet's atmosphere at energies ranging up to 1020
(one followed by 20 zeroes) electron volts or more. Every possible event involving protons of energies up to at least that level has already happened on this planet many, many times.
The Large Hadron Collider accelerates protons under controlled conditions and collides them with one another at energies not exceeding, at the most, 1013
electron volts (one followed by thirteen zeroes). In other words, it produces artificial cosmic rays one ten-millionth
as powerful as many of the cosmic rays that strike our planet every single day.
So yes, we can conclude that the LHC will not bring about the end of the world.
But if this stuff happens every day, why do we need to study it in a big expensive machine in Europe?
Well, as I said, we know the large-scale consequences of two protons bumping into each other... which is to say, "not a hell of a lot." It happens constantly, all the time, and the world does not blow up, nor does it collapse into a black hole.
What we don't know is exactly what the small-scale consequences are like. And by "small" I mean very
small. As in fragments that wink into existence for a infinitesimal fraction of a second and are gone again. We have to pay very close attention indeed to catch all the details.
Yes, detectors for naturally occurring cosmic rays have been built, and they have in fact taught us quite a bit. But we can't precisely control what goes into them. Or how energetic it is when it arrives. Or what angle it comes from. Or even when the collision will take place.
It's like trying to learn orthodonture by waiting for an orthodontist to walk by, coincidentally mention that he's an orthodontist, and say something enlightening into his cell phone before wandering out of earshot again. Take notes for a few thousand years and you might have a rough idea how braces work. But going to medical school— an environment in which we can expect to reliably encounter orthodontists under controlled conditions— is a lot more effective.
Now, not having actually been to medical school ourselves, we might worry that going to medical school will result in the creation of a black hole which annihilates our planet. After all, we
have not personally tried it, so we don't know firsthand that this won't happen.
However, we do have an abundance of evidence that other people are going to medical school already, all over our planet, every day. So even though we don't know all the ins and outs of retainers yet, we can safely conclude that our planet will not be destroyed by attending medical school.
Going to medical school would teach us to be orthodontists, which sounds pretty lucrative. But what's the payoff of building the Large Hadron Supercollider? Well... just a chance to confirm what we think we know about the fundamental laws of the universe.
That may not seem immediately valuable to you. But to take one small example, lessons learned from quantum physics are key to the day to day operation of the computer you're using to read this. Coping with the consequences of electron tunneling and other "too weird to be real" quantum phenomena has long since become an engineering reality.
Just as important, seeking to better understand the world is one of the main joys of being human. No, we shouldn't take dumb risks as a species. But we should absolutely educate ourselves, find safe ways to learn more, and carry out those experiments. And the latter is what is happening at the Large Hadron Collider.
If you want to express your concerns about policies which endanger the survival of the entire species, I suggest investing your energy in campaigns to reduce the proliferation of nuclear weapons, the potential use of which poses a clear and present danger to humanity's existence. Alternatively, demand funding for a near earth asteroid detection and deflection
research program with a level of annual funding that comes anywhere close to the amount of money spent to make either "Deep Impact" or "Armageddon."
I've tried to inject some humor here, for my own sanity as well as yours, but I'm not trying to be dismissive at all. This stuff is not that difficult to understand, or it shouldn't be. I hope this is helpful.