• Choose a category
• All
• Classic-Fiction

By Root 1090 0

Mangano ruled out even that case too, since the gravitational attraction of much denser astrophysical objects—namely, neutron stars and white dwarfs—is sufficiently strong to stop black holes before they could escape. Ultra-high-energy cosmic rays hitting dense stars with strong gravitational interactions would have already produced exactly the sorts of black holes that are potentially possible at the LHC. Neutron stars and white dwarfs are much denser than the Earth—so very dense that their gravity alone would suffice to stop black holes in their interior. If the black holes had been produced and had been dangerous, they would have already destroyed these objects that we know have lasted billions of years. The number of them in the sky tells us that even if black holes exist, they certainly are not dangerous. Even if black holes were formed, they must have disappeared almost immediately—or at worst left tiny innocuous stable remnants. They wouldn’t have had sufficient time to do any damage.

On top of that, in the process of accreting matter and destroying such objects, black holes would have released large amounts of visible light, which no one has ever seen. The existence of the universe as we know it and the absence of any signal of white dwarf destruction is very convincing proof that any black holes the LHC could possibly make cannot be dangerous. Given the state of the universe, we can conclude that the Earth is in no danger from LHC black holes.

I’ll now give you a moment to breathe a sigh of relief. But I’ll nonetheless briefly continue with the black hole story—this time from my perspective as someone who works on related topics such as the extra dimensions of space necessary for low-energy black holes to be created.

Before the black hole controversy blew up in the news, I’d already become interested in the topic. I have a colleague and friend in France who used to work at CERN but now works on an experiment called Auger, which studies cosmic rays as they descend through our atmosphere toward Earth. He complained to me that the LHC takes away resources that can be used to study the same energy scales in his cosmic rays. Since his experiment is far less precise, the only type of events it might find would be those with dramatic signatures such as decaying black holes.

So along with a postdoctoral fellow at Harvard at the time, Patrick Meade, I set out to calculate the number of such events they might observe. With a more careful calculation, we found that the number was much less than physicists had originally optimistically predicted. I say “optimistic” since we are always excited about the idea of evidence for new physics. We weren’t concerned about disasters on the Earth—or in the cosmos, which I hope you now agree were not a real threat.

After recognizing that Auger wouldn’t discover tiny black holes, even if higher-dimensional explanations of particle physics phenomena were correct, our calculations made us curious about the claims other physicists had made that black holes could be produced in abundance at the LHC. We found that those rates were overestimates as well. Although the rough ballpark estimates had indicated that in these scenarios, the LHC would copiously produce black holes, our more detailed calculations demonstrated that this was not the case.

Patrick and I had not been concerned about dangerous black holes. We had wanted to know whether small, harmless, rapidly decaying higher-dimensional black holes could be produced and thereby signal the presence of higher-dimensional gravity. We calculated this could rarely happen, if at all. Of course, if possible, the production of small black holes could have been a fantastic verification of the theory Raman and I had proposed. But as a scientist, I’m obliged to pay attention to calculations. Given our results, we couldn’t entertain false expectations. Patrick and I (and most other physicists) don’t expect even small black holes to appear.

That’s how science works. People have ideas, work them out roughly, and then they or others go back and check