Concern Over Creating Black Holes

Maria Williams writes to tell us about worry surrounding the impending startup of CERN's Large Hadron Collider. Some fear that the device, in creating mini black holes, could jeopardize Life As We Know It. While the tiny black holes should evaporate quickly — throwing off so-called Hawking radiation that can be detected — CERN software developer Ran Livneh reminds us that "Any physicist will tell you that there is no way to prove that generated black holes will decay." The LHC site assures us there's nothing to worry about. The flap is reminiscent of the time the Relativistic Heavy Ion Collider went live. The worry then was that "negative strangelets" could gobble up the world.

Okay...

[addaon]

Being cautious about a potentially real issue is one thing, but of course the big issue here is that collisions of similar energy happen, if not commonly, at least not entirely rarely due to cosmic rays. If the world could be destroyed by the side-effects of such a collision, we wouldn't be here to be nervous about it.

The biggest word in that sentence

[Weaselmancer]

While the tiny black holes should evaporate quickly...

The biggest word in that sentence is should.

Re:The world didn't end last time...

[dgatwood]

I don't think I buy that reasoning. That's like saying that a {particle beam, laser} won't work because the hole at the end of the tube is only big enough for one {atom, photon}.

Except it's worse than that. As soon as things shift around a little so that a single atom goes in, the event horizon is now slightly larger. Repeat ad infinitum. All it takes is an occasional atom getting through.

A microscopic black hole either dissipates or it doesn't. If it does, great. If it doesn't, we have a problem. It may take millennia to become a serious problem, but....

Re:OK, imagine the black hole not decaying...

[Anonymous Coward]

nah, the small black hole will just drop through the earth's crust, oscillating back and forth through the planet eating up matter along its way, slowly getting bigger. Hardly a "we'll all die simultaneously" scenario. Heck, it could have already occured, and we wouldn't know the difference for a *long* time.

Re:Cosmic rays have prior art

[joe_n_bloe]

Yeah - the fundamental problem with all these "supercolliders will destroy the Earth/Universe" hypotheses is that all these "extreme" conditions have existed here and there throughout the universe since the beginning of time.

Re:The world didn't end last time...

[MORB]

So what?

If it doesn't destroy the world, scientific knowledge advances.
If it does, no onw will be around anymore to worry about it.

Not this again

[xihr]

Why does this keep coming up? Natural ultra-high energy (UHE) cosmic rays have vastly higher energies and do no such thing. The highest-energy cosmic ray recorded is 300 EeV (that's exaelectron-volts -- 3 x 1020 eV. We get showered by these cosmic rays all the time; if high-energy particle collisions were going to make miniature black holes which somehow don't evaporate and kill us all, then it would have happened long before the Earth finished forming.

Re:You are correct

[sjames]

Actually, the idea behind Hawking radiation is that the intense gravity gradient of a black hole causes virtual particles to become actual near the event horizon. One goes in and the other escapes. It doesn't matter which one went in. Of course, a pair of particles just appearing out of the vacuum leaves a "hole" that must be filled (otherwise cionservation of mass/energy is violated). The energy to fill the hole tunnels out of the black hole itself. The net result is that it loses the mass of the escaped particle.

It's worth noting that the size of black hole we're talking about here would evaporate in a small fraction of a second, most likely before it would even encounter another particle. It would have to somehow absorb a few hundred metric tons of matter to even last 1 second.

Should all of this theory prove wrong, we may still feel safe since collisions with this level of energy DO occur in nature already and obviously haven't created "The Black Hole that Swallowed the Earth".

Re:Natural Particle Accelerators

[treeves]

Fortunately, my cross-section 3.2E20 eV protons is MUCH smaller than my cross-section for 55 mph baseballs.