# Black Hole Formed From LHC?

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1. Mar 15, 2013

### PhysicsWanabe

Hey I heard from a couple differnt places on the internet that there's a possibilty that a black hole hypothetically could be formed by the LHC. I thought that black holes were formed by the implosion of a huge star that keeps going in on itself due to gravity. Is it true that this could happen at the LHC?

2. Mar 15, 2013

### fzero

It is indeed true that the typical example of black hole formation is in the collapse of a sufficiently massive star. However, we believe that a small black hole can be formed whenever mass is compressed beyond a certain size. For example, if you had a Planck mass ($\sim 10^{-8}~\mathrm{kg}$) compressed to within a Planck length ($\sim 10^{-35}~\mathrm{m}$), you would create a black hole. In particular, in the very early universe, when all of the mass in the universe was much closer together, the formation of so-called primordial black holes would have been possible.

In certain hypothetical extensions of the Standard Model (mainly models with "large" extra dimensions of spacetime), the true Planck length could be longer than the $\sim 10^{-35}~\mathrm{m}$ distance we derive from measuring gravity at long scales. In these models, at some high energy, the strength of gravity becomes sharply stronger than what we measure at the normal energy scales of the solar system or table-top experiments. In principle, above this characteristic energy, the formation of black holes would become feasible. Such small black holes wouldn't be expected to be very dangerous, because they would decay quickly due to Hawking radiation.

It is unlikely that black holes would be produced at the LHC. The mechanism relies on highly speculative ideas and no other signatures of this type of new physics has been seen so far. Wikipedia has extensive discussions at http://en.wikipedia.org/wiki/Micro_black_hole and http://en.wikipedia.org/wiki/Safety_of_high_energy_particle_collision_experiments

3. Mar 15, 2013

### ZapperZ

Staff Emeritus
You are a bit late to the party.