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Sunday, March 30, 2008

No, the LHC won’t destroy the Earth

I linked to this subtly in my post about my trip to the UK next month to visit Europe’s new particle accelerator, the Large Hadron Collider (LHC), but it deserves more attention.

Two men are suing to stop the LHC from being switched on, saying it may be dangerous and might even destroy the Earth:

But Walter L. Wagner and Luis Sancho contend that scientists at the European Center for Nuclear Research, or CERN, have played down the chances that the collider could produce, among other horrors, a tiny black hole, which, they say, could eat the Earth. Or it could spit out something called a “strangelet” that would convert our planet to a shrunken dense dead lump of something called “strange matter.” Their suit also says CERN has failed to provide an environmental impact statement as required under the National Environmental Policy Act.

[…]

The lawsuit, filed March 21 in Federal District Court, in Honolulu, seeks a temporary restraining order prohibiting CERN from proceeding with the accelerator until it has produced a safety report and an environmental assessment. It names the federal Department of Energy, the Fermi National Accelerator Laboratory, the National Science Foundation and CERN as defendants.

First off the bat, this sounds nuts, but really it’s not so nuts that we shouldn’t look into it. There are two causes for some concern: one is that LHC might create a black hole which would eat the Earth, and the other is that a very odd quantum entity called a strangelet might be created, with equally devastating results.

However, I don’t think there’s anything to worry about. I want to make that clear up front.

The LHC will slam subatomic particles together at fantastic speeds. The collision in a sense shatters the particles and all sorts of weird beasties are created in the aftermath. This give physicists insight into the basic quantum nature of the Universe. The higher the energy of the collision, the more interesting stuff you get. LHC will be the most powerful collider ever built, and is expected to provide really new looks at the quantum world.

That’s what has the two litigators worried.

If two subatomic particles collide at high enough speed, it’s possible that they will collapse into a black hole. If that happens, it would fall through the Earth and, well, you can guess what bad things would happen then*.

However, studies done by CERN show that the energies generated will be too low to make black holes. Also, due to a weird effect called Hawking radiation, the tiny black holes would evaporate instantly. The two litigants, however, say that Hawking radiation is not an established fact, and therefore we should be more careful. While that’s technically true, they forgot something important: the same rules of quantum physics that make a black hole in a subatomic collision also indicate they would evaporate. So if you’re worried they won’t evaporate, then you shouldn’t be worried they’d be created in the first place.

Same goes for the creation of a quantum strangelet. This is a weird conglomeration of particles called quarks, and if a strangelet comes into contact with normal matter can convert it into more strangelets. The idea is that these can cause a chain reaction that turns all available matter into strangelets. That would be bad.

However, first, strangelets are completely theoretical, and again even if they are real it’s incredibly unlikely they would be created even by LHC. And even if they were created, the chances of them being a danger are very small. A study a few years ago by physicists at MIT, Yale, and Princeton shows this to be the case; as they point out, higher energy particles hit the Moon all the time. If strangelets could be created in this way, the Moon would have converted to a big ball o’ strangelets billions of years ago.

So I think that considering things like this happening is good — after all, we’re walking into new territory here — but in this particular case the litigants are wrong. A lawsuit seems like overkill. In fact, it’s so odd that my skeptical gland was tweaked, and I decided to look into the litigants’ backgrounds.

Walter Wagner apparently has a physics background, but was involved in a similar lawsuit over the Brookhaven collider a few years back, which turned out to be completely baseless.

As for the other, Luis Sancho, he’s, well, how do I phrase this delicately? He’s a bit outside the mainstream. Actually, way outside the mainstream. In fact, totally and way way far outside the mainstream. I don’t think you can even see the mainstream from where he is.

While dismissing the idea of any danger from LHC due to these factors would be an ad hominem and therefore unfair, I think it adds a dimension to this case that’s good to keep in mind.

Again, I’m not worried. I don’t see any basis for their fears, and certainly not for their lawsuit.

So I’m still greatly looking forward to visiting the LHC in April. It’ll be a fantastic glimpse into the next generation of physics, and will open up new vistas for us to explore.

If the court agrees to let it run, of course.

Original here

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