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One theoretical speculation about why gravity is so much weaker than the other known forces postulates the existence of additional dimensions beyond the familiar three. If this idea is true, then the LHC might be able to create microscopic black holes. If observed, they would have a major impact on our understanding of the laws of physics.

According to the laws of physics as we currently understand them, it is impossible to make microscopic black holes at the LHC. There is simply no way to pack enough energy into a small enough space to trigger the mechanisms that make a subatomic singularity.

However, many speculative ideas are being tested at the LHC, some of which predict microscopic black holes. If a microscopic black hole were to be produced in collisions at the LHC, it would evaporate immediately, producing a distinctive spray of sub-atomic particles of normal matter.

One idea about microscopic black holes was outlined in earlier articles ( here and here ). Those articles described a potential answer to the question of why gravity is so much weaker than the other forces. The proposed solution invokes the idea that perhaps there are undiscovered additional dimensions. In this scenario, gravity is just as strong as the other forces, but gravity can enter these extra dimensions while the other forces can’t. Because gravity has more places to spread out, it appears weaker when viewed in our familiar world of three spatial dimensions. When studies are done at the small scales possible at the LHC, perhaps gravity will appear to become suddenly stronger.

If gravity turns out to be strong, then perhaps it actually is possible to make microscopic black holes. With this theoretical premise in mind, CMS physicists searched for microscopic black holes. If they exist, physicists believe they will decay via Hawking radiation, first postulated by noted physicist Stephen Hawking. No evidence was observed that was consistent with the creation of black holes. The only way microscopic black holes can be made at the LHC is if gravity somehow becomes much stronger, kind of like an atom suddenly becoming nearly as big as the visible universe. If microscopic black holes ever are observed, it will totally rewrite our understanding of the universe. This was the first such search at the LHC, but surely not the last.

Read more about this CMS result.

— Don Lincoln

Physicists at Brown University have had a long interest in searching for microscopic black holes, which naturally led to this early CMS paper.

These physicists form part of the LPC Users Support Group and provide invaluable help necessary to make the Fermilab CMS effort run smoothly. From desktop support to CMS Analysis techniques and tools, without these mechanics, nothing would get done.