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| DailyGalaxydotcom |
I've used this artist's rendition before in a high school physics class I was teaching. It's one of my favorites.
Black Holes have fired the public imagination since its coining by John Wheeler, (probably because "Magnetospheric Eternally Collapsing Objects" is quite a mouthful!) similar to the thoughts of near-light speed time dialation and the "twin paradox." Both popular physics books and science fiction have discussed this element of General Relativity, so it is natural that part of the public would voice concerns about the LHC creating "mini black holes" and swallowing the planet earth (that would also be a real bummer for physicists).
Black Holes have fired the public imagination since its coining by John Wheeler, (probably because "Magnetospheric Eternally Collapsing Objects" is quite a mouthful!) similar to the thoughts of near-light speed time dialation and the "twin paradox." Both popular physics books and science fiction have discussed this element of General Relativity, so it is natural that part of the public would voice concerns about the LHC creating "mini black holes" and swallowing the planet earth (that would also be a real bummer for physicists).
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| University of Chicago Department of Astrophysics |
In response to some of the comments below, let me explain one of the concerns over the standard assurances given by particle physicists about the safety of the LHC.
Their argument is that the Earth has been bombarded by high energy cosmic rays for billions of years. These particles would have collided with particles in our atmosphere at much higher energies than are possible at the LHC. So if a catastrophe were possible, it would have happened by now.
That means the continued existence of the Earth, and indeed many other astronomical bodies, is powerful evidence that the LHC is safe.
The problem is this: there is an important difference between the collisions that occur in the atmosphere and those that occur at the LHC.
The problem is this: there is an important difference between the collisions that occur in the atmosphere and those that occur at the LHC.
Cosmic rays hit the atmosphere at a substantial fraction of the speed of light. That means the debris from these collisions also travels at a substantial fraction of the speed of light, giving it limited time to interact with the Earth.
The collisions at the LHC are different. These involve two beams, both travelling at almost the speed of light but colliding head on. So the collision occurs at rest with respect to the Earth.
The collisions at the LHC are different. These involve two beams, both travelling at almost the speed of light but colliding head on. So the collision occurs at rest with respect to the Earth.
That's a significant point. It means that the debris from the collision can hang around for longer and so have a greater chance of interacting with the Earth.
When this effect is taken into account, it is not at all clear that similar events have taken place regularly in our atmosphere or indeed anywhere else.
Physics arXiv: Micro black holes in the laboratory
When this effect is taken into account, it is not at all clear that similar events have taken place regularly in our atmosphere or indeed anywhere else.
Physics arXiv: Micro black holes in the laboratory
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