Who’s afraid of the LHC?
Gail Collins’ latest column had me literally laughing out loud. It’s called “Digging Ourselves a Black Hole,” and it’s about the hyped-up fears that the Large Hadron Collider will create a singularity that will devour our planet. The LHC is a new particle accelerator built in Switzerland and intended to go into full operation later this year. Collins simultaneously debunks and embraces the black hole speculations, lending a bit of perspective to more common concerns:
I am bringing this up now because it is always important to remember that things could be worse. You may be worried about a new cold war or a major bank failure, or afraid of losing your job or your house or your credit rating. You may be depressed by your first look at the fall TV schedule. …
Perspective is all. If you’re going to fret, I say, fret about that black hole. For one thing, it makes it much easier to schedule unpleasant tasks for the second half of September. Heads, the planet survives. Tails, the root canal never happens.
I had a very similar realization right around when I took my first quantum mechanics course. One notable thing about quantum physics, as distinguished from classical physics, is that particles are described as having some small probability of being in places which are classically forbidden. Without getting too technical, let me make an analogy. Imagine you had a ball rolling back and forth in a valley, but on the other side of each hill is another valley. Classically, unless you let go of the ball at one hill’s peak, there’s no chance of it rolling all the way over into the next valley. It’s limited by the amount of total energy it has — potential plus kinetic. On the other hand, if the ball was a tiny particle governed by quantum mechanics rather than by macroscopic rules, there would be a small chance of it tunneling through one of the hills and popping out on the other side. (When I say small, I mean extremely minuscule. But nonzero.)
When I first learned about quantum tunneling, I had a horrifying thought: This means there is some chance of me spontaneously falling through my chair and the floor below me and landing on some poor unsuspecting student in the classroom below us! But then I had a more horrifying thought: Because the probability of tunneling decays exponentially with distance in the classically forbidden region, it’s many orders of magnitude more likely that I fall partway through the floor and then get stuck. Ew.
Of course, my body is made up of so many atoms, and even my flimsy chair was so thick from a quantum-mechanical perspective, that the probabilities we’re talking about here are so tiny as to be effectively zero. (I would be more likely to win the lottery while being struck by lightning for the second time and being bitten by a shark.) Nevertheless, “effectively zero” is not the same as zero. It is still technically possible… yet somehow, we manage to go on. (We laugh in the face of danger every day, we physicists. That’s why we’re heroes.)
In a way similar to this quantum tunneling issue, the black hole fears about the LHC are not entirely unfounded, but they do give a great example of making mountains out of molehills. We don’t know everything about particle physics — that’s why the LHC was built, after all — so we have a couple different theoretical questions that we’re trying to answer. The old “Standard Model” theory says that the LHC will not yield energies high enough to create black holes. It is hypothesized that the Standard Model needs to include large extra dimensions in order to account for various unresolved questions, and in very large-scale experiments like LHC the energies needed for black hole production might possibly be accessible. In fact, one of the many purposes of such large-scale experiments is to test for evidence that would support this hypothesis. Even if we did see black holes, though, they would be so tiny that they are likely to evaporate almost immediately by Hawking radiation. We don’t have any direct evidence supporting the idea of Hawking radiation yet, because its levels would be very small and difficult to detect, but it has held up to thorough theoretical checks and the safety of LHC has been accepted by the vast majority of physicists.
Recap: The mainstream theory says black holes cannot occur at LHC. One alternative hypothesis posits a possibility of micro black holes at LHC, but the mainstream understanding of these black holes is that they would evaporate almost immediately and pose no danger whatsoever.
Recap of the recap: You need to go to the alternative alternative theorists to get someone who believes there might be a danger from black holes at LHC.
Don’t get me wrong, though. The LHC makes me very afraid — just not about black holes. I’m afraid for the future of pure science research in the US. The LHC was built in Switzerland, already the home of CERN. ITER is going to be built in France. No large-scale experimental physics facilities are planned for sites in the US. Back in the early 1990s, the Superconducting Supercollider (SSC) was being built in Texas, but Congress decided to cut funding and the project had to be canceled.
It used to be the case that physics professors would come to American universities and research facilities to participate in international collaborations. If you were involved in a large-scale, groundbreaking project, chances were good you’d be spending part of the year in the US. Now that funding and facilities for new experiments are not available in the States, American professors and researchers are going to Europe and Asia for several months at a time to get their research done. I’m not saying this is objectively bad — science should be done everywhere, and people of every nationality are equally capable of doing it — but it’s definitely bad for the United States. When research is done here, researchers visit here and, for their careers, want to live here. A significant number of them start billion-dollar companies here, sometimes based on spinoff technology from their research and sometimes spontaneously spawned in the fertile intellectual environment of research-focused communities. Other already-existing companies also benefit from new discoveries. This creates jobs, contributes hugely to the economy in general, and raises the American standard of living. And Congress decided that this is not worth considering as a national priority? Now that’s terrifying.
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Good post, like your site and the dynamic I’ll try to keep up for a bit.
Cheers!
I appreciate this entry a lot, because I’m about as much of a layman in physics as you’re going to get without actually talking to an elementary school student. This was a really good explanation not just of the LHC itself, but of why people are flipping out over it.
I particularly appreciated the note about American science funding. It’s a real shame that America used to be known for science, and now we’re known (at least according to everybody I know in other countries) for fundamentalists. Ah, how the mighty have fallen. This time “the mighty” was us.
[...] Who’s afraid of the LHC? Where it is explained that while the appearance of a planet destroying black hole is possible on September 10th , it isn’t very probable. [...]