Originally Posted by Warren Platts

The point we doomsayers have been making is that they are not the same experiements. mBH's in the LHC will result from two perfectly head on collisions; such LHC induced mBH's will have low velocities relative to the Earth, allowing them to be captured by Earth's gravity, unlike cosmic ray induced mBH's that would pass harmlessly through Earth. Moreover, that such black holes would not grow rapidly is not excluded by the first principles of physics, as we know them so far.

So they attempt to constrain their physics equations through the use of astrophysical data. That is, they assume that white dwarfs are dense enough to trap cosmic ray induced mBH's. However, that assumption depends in turn on the plausibility of the "semiclassical approximation"; but mBH's exist deep within the "quantum gravitational regime" that we know little about. Quantum gravitational effects may cause mBH's to violate the semiclassical equations, allowing cosmic ray induced mBH's to pass harmlessly through white dwarfs, just as the semiclassical equations allow cosmic ray induced mBH's to pass harmlessly through ordinary stars.

Therefore, there is a built-in uncertainty in whether the long-term presence of white dwarfs can actually serve as a constraint on the laws of particle physics with regard to the growth rates of mBH's.

And if there is a reasonable uncertainty--no matter how small--the knowledge we might gain--no matter how profound--is not worth the risk of destroying the Earth. Especially when there are alternatives available--like constructing colliders with only a single beam instead of two beams aimed at each other.