Some theories suggest that the formation of tiny ‘quantum’ black holes may be possible. The observation of such an event would be thrilling in terms of our understanding of the Universe… But would it be safe?

Two types of black holes

Black holes form in space when certain stars, much larger than our Sun, collapse on themselves at the end of their lives. They concentrate a very large amount of matter in a very small space. They are so dense that the gravity they exert is such that not even light can travel out of them.

Speculations about black holes at the LHC refer to particles produced in the collisions of pairs of protons. These are microscopic – or quantum – black holes. Scientists are not at all sure that quantum black holes exist.

Nature’s experiment

The physical part of the LHC experiments – colliding particles – happens in nature all the time. We know, for example, that the Earth is constantly bombarded by cosmic rays: when cosmic rays hit the atmosphere, particles are colliding with one another in much the same way as in the collisions planned at the LHC.

Just as we know that the Earth is safe under the natural bombardment from cosmic rays, so we know that recreating these collisions poses no threat to the Earth. Nature’s collisions also reach much higher energies than those at the LHC.

What if collisions at the LHC produced a black hole?

The creation of a quantum black hole at the LHC would be very surprising, but very exciting indeed. It would allow physicists to learn about nature’s most elusive force – gravity.

If microscopic black holes do appear in the collisions created by the LHC, they would disintegrate rapidly, in around 10-27 seconds following Standard Model or supersymmetric particles’ decay, thus creating events containing an exceptional number of tracks in the LHC detectors, which scientists would easily spot. Finding more on any of these subjects would open the door to yet unknown possibilities.

What would be the significance of the creation of a black hole at the LHC?

The creation of a black hole at the LHC would confirm theories that our universe is not 4 dimensional (3 space plus 1 time dimensions), but indeed hosts other dimensions. It would be quite a spectacular philosophical outcome! In the same way that the theory of relativity or of quantum mechanics revolutionized our way of thinking, discovering the existence of extra dimensions would be a major new milestone in our understanding of the Universe.

There is no obvious application for knowing this. Many people will start speculating about using these extra dimensions for space and time travel, or as a source of clean energy, and who knows what else. [CERN]