They are planning to create a new particle accelerator that can smash particles together at a much higher energy than the LHC.

If in the process we observe the decay of a micro black hole, would that be proof of additional spatial dimensions?


2 Answers 2


Extra dimensions are predicted in string theories which are not measurable in the standard versions, they are compactified :

In compactification, some of the extra dimensions are assumed to "close up" on themselves to form circles. In the limit where these curled up dimensions become very small, one obtains a theory in which spacetime has effectively a lower number of dimensions.

This is the space time we live and experiment in.

Since about 1998 there has been a promise of large extra dimensions to be seen in particle experiments. I remember this paper and in a few years there were also programs generating the appearance of micro black holes in the future LHC experiments.

CERN is still answering questions about the dangers of black holes in the accelerator eating up the earth: there are none.

The experiments search for the signature of these small black holes, and have only given limits up to now , as you can see if you go to the document server and search for "limits on large extra dimensions" .

So if in a new collider there is a signature for a mini/small black hole, then it will be a validation for models that propose large extra dimensions. The signature would be for a jet of particles showing just thermodynamic behavior and not following the strong interactions which generates the usual jets.

  • $\begingroup$ Can evaporation from a small black hole transform it into a micro black hole? $\endgroup$ Jan 17, 2019 at 23:45
  • $\begingroup$ @JoãoBosco in the end the small black holes of cosmology evaporate completely following thermodynamics, so the end last products woud be the same as for the small black holes in the string models of large dimensions. $\endgroup$
    – anna v
    Jan 18, 2019 at 4:53

If I recall rightly, Hawking pointed out the possibility of what he called primodorial black holes on his paper on black hole evaporation; these are black holes created during the very first moments of the Big Bang.

As amazing an achievement the LHC is, and any subsequent collider (Japan has cancelled plans for a new accelerator that would move on from the LHC), it hardly at approaches the kind of energies and densities that were found then.

So, no, I wouldn't hold out for any such chimerical and ill-advised hopes.


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