Princeton University scientists have calculated the gravitational interactions between colliding particles modeled as black holes and found that a black hole formed if two particles collide with a total energy of about one-third of the Planck energy.

While the Planck energy is a quintillion times higher than the LHC’s maximum, if space actually has more dimensions (predicted by certain theories) that are curled into little loops too small to be detected except in a high-energy particle collision, those extra dimensions might effectively lower the Planck energy by a huge factor.