Monday, March 31, 2008

Particle smasher 'not a threat to the Earth'

I'm loving the near-apocalyptic sci-fi-esque headlines that are cropping up as the LHC nears it's summer 2008 completion date.

Botanist sues to stop CERN hurling Earth into parallel universe.

Particle Smasher 'not a threat to the Earth'

My grasp of black holes, strangelets and strings is tenuous at best. So while I'm willing to trust the experts on this one, I still frequently wish that I understood the physics better. This comment from QuantumLeap at BoingBoing seems informed and helpful (if somewhat foreboding in it's final line):

First, let me disclaim that I worked for CERN for a few years and now work for a US National Lab, doing research work for an experiment within the LHC (the ATLAS experiment, )

This mini-black-holes we expect to generate at LHC don't look at all like what most people associate to them. Have a look:

In fact what we see is the Hawking Radiation ( emitted by the evaporating black hole, which should disappear in about 10e-25s. Meaning, if it were traveling at the speed of light it would cover a distance of less that the radius of an hydrogen atom. This is a 8TeV black hole.

And . . . particle collisions way more energetic that that happen every day in our atmosphere, and we're still around...

The danger of strangelet conversion ( is even more exotic since it's not only merely a vague theoretical possibility as it needs matter densities way higher that what you have on earth to be of any concern. A strangelet, if it exists, is even more unstable that a mini-black-hole and so at the speed of light will barely cover more than the distance of a proton radius before disintegrating. Only in a very packed and dense environment (like a neutron star) it would be able to propagate.

Anyway, soon all this debate will be over...

From the virtual LHC center:

LHC is the Large Hadron Collider, an accelerator being built at CERN near Geneva, Switzerland. When it is complete in the summer of 2008 it will be the largest and highest energy accelerator in the world. Here are the stats:

* Type of collision: proton-proton
* Center of Mass Energy at Collision: 14 TeV (7 times energy of the Fermilab Tevatron)
* Diameter of Ring: approx 27 km
* Average depth of ring below ground: approx 100 m
* Main particle Detector Systems: ATLAS, CMS, LHCb, ALICE
* Hoping to Discover: Higgs boson, Graviton, Supersymmetric Particle, Extra Dimensions...


Chris said...

I too am way out of my depth, but for what it's worth, it doesn't sound too dangerous to me. Macroscopic black holes would indeed be VERY stable, but such tiny ones could lose enough mass just from the radiation they give off to be completely nullified quickly.

An even better argument for not worrying; I think it's quite likely that collisions of the type being caused really do happen all the time naturally (we just don't know where to point the fancy recording equipment). When you consider the small size of these particles, how many are hurling into the atmosphere, and the all the space in our atmosphere, it almost seems inevitable. I wouldn't be surprised if it turned out that tiny black holes were produced often right under our noses, and never got noticed. On the other hand, never underestimate the rate at which our science can outpace our good sense.

One more note - I don't really know what a Higgs Boson is, but I think anything with the name of Higgs attached is some pretty weird stuff; if I remember right, the Higgs field (somewhat like an electrical or gravitational field) permeates the entire universe and IS THE CAUSE OF INERTIA! That is, the value of the Higgs field sets the level at which mass resists accelleration. Without it, objects, no matter how massive, could be pushed around with practically no force. All this supposedly because (?) Higgs particles are stuck at some elevated energy level, and can't sink back down to zero due to being in some kind of theoretical "bowl" and needing a boost to get over the lip.

If any of that made any sense!

Chris said...

By the way, any thoughts on the testing for extra dimensions? I know that's a favorite issue. If "science" gives you conclusions you feel in your heart to be wrong, will you believe them?

I was thinking about doing a post on how the strength of gravity at tiny distances allows one to test for extra dimensions.

Rachael said...

To be honest, this stuff is so far over my head that I don't feel capable of having any thoughts on the testing for extra dimensions. I'm intrigued of course, but I don't understand the science. I doubt I'll be in any position to critically evaluate findings from the LHC so the best I can do is suspend belief -- for pratical purposes I'll defer to what the most credible experts are saying.

I know this much though -- I don't care what my heart tells me about scientific matters, hearts have a rather poor track record for this sort of thing -- especially mine! ;)

I've never heard anything about how one might detect extra dimensions, so I'd love to read that post! Yes -- the science is over my head (at least for now) -- but obviously I appreciate learning whatever I can about it!

Daniel said...

"If 'science' gives you conclusions you feel in your heart to be wrong, will you believe them?"

I've been wrestling with the craziness of quantum mechanics, and I've had to just force myself to give in and believe it. So yes, if it's conclusive enough to convince an entire scientific community, I suppose I'll believe, albeit with a tiny grain of salt until my common sense gives in too.

Chris said...

Me too with the quantum physics... I started out reading Einstein, who was (of course) brilliant, and also totally against the standard interpretations of quantum physics. In loyalty to him, I still hope to think up some consistent explanation for the experimental results I know that jives with his ideas.

But in general, I do trust some percentage of the science community to be critical thinkers, so I guess I agree that if the community is unanimous (or nearly), then I'm persuaded.