Scientists Not So Sure 'Doomsday Machine' Won't Destroy World

[m42]

Three physicists have reexamined the math surrounding the creation of microscopic black holes in the Switzerland-based LHC, the world's largest particle collider, and determined that they won't simply evaporate in a millisecond as had previously been predicted.

http://www.foxnews.com/story/0,2933,483477,00.html

Is does seem a bit nonsensical to enable this device without validating (within reason) the mathematics behind it.

Perhaps not as nonsensical as the fact that our tax dollars helped fund this snafu. *grin*

[eternaltraveler]

it is completely irrelevant to the fate of the earth whether or not these mini black holes evaporate or not

There are a few other convenient laws of physics that make this so.

Firstly is the conservation of mass and energy. Meaning no more than the collision energy and the mass of the particles that create the black hole could contribute to it’s initial mass. With collision energies in the 14 TeV range, or 2.2 μJ (from Wikipedia). This amounts to around 10^-21 kilograms. The diameter of a black hole of this mass is somewhere in the plank range, I’m not going to bother calculating it, and instead will use an example of a black hole with a mass 36 orders of magnitude larger for the remainder of this post.

That is to say a black hole with the mass of somewhere around 10^15 kg. This gives a black hole with the radius of about one nanometer (convenient eh?). Now lets assume our LHC violates the conservation of mass and energy and produces a black hole 36 orders of magnitude larger than it can, and lets assume it does not evaporate, and matter is sucked into it at the speed of light through it’s entire surface area of about 12.5 nm^2. 1.25x10^-17 m^2 * 3x10^8 m/s = 3.8x10^-9 m^3/s. or about 4 cubic millimeters per second.

As it gained mass it would certainly accelerate. After it doubled in mass it’s surface area would increase by a factor of 4 increasing the amount of material it could swallow at the speed of light to 16 cubic millimeters per second. How long would this take? Well being lazy lets just assume it swallows the whole 16 cubic millimeters per second with a density of 25 grams per cubic centimeter the whole time(this will give us a lower bound).

1.6*10^-8 m^3/s * 2.5*10^4 kg/m^3, 4*10^-4 kg/s.

That’s something like 2.5*10^18 seconds in order to double in mass as a lower limit. Billions of years.

Yes, this was for a black hole with the initial mass somewhere around 36 orders of magnitude larger than the initial mass could be in the LHC. All the protons will decay in the universe before an LHC generated black hole could even be noticeable.

How the LHC crowd ever let there be a debate over hawking radiation somehow relating to the fate of the earth is beyond me. The first time a reporter asked one of these physicists “won’t it grow and suck in the earth!?” the answer shouldn’t have been “probably not, we think there might be his hawking radiation stuff that will make it not grow”. The answer should have been “No, under no circumstances could such a black hole swallow the earth”

thanks to Jay Fox at imminst for the reasoning