Black holes


Black holes are something that is depicted a lot in Science fiction. Most of the time they are depicted as massive objects somewhere in space, but not all black holes are like that. A black hole is an object which has an Schwarzschild radius that is larger than its actual radius. The Schwarzschild radius of an object with mass is the distance from that object at which light cannot escape the gravitational pull of the object. Although it’s easiest to imagine this in the case of a very massive object it is not an requirement for being a black hole, what is needed is a very high density (high amount of mass in a small volume). These kinds of black holes (very small) are the things some physicists freaked out about with the LHC. They thought the LHC might create a small black hole that would grow fast enough as to swallow the hole earth. This is however very improbable because of something called hawking radiation. Hawking radiation is caused by the creation of a particle pair where one of the particles has to be the antimatter counterpart of the other, in our example we take the electron(e) and the positron(e+), the positron can be understood as an electron but with positive charge instead of negative charge.  This creation can take place due to the energy time uncertainty principle which says that the more certain you are about the duration of an reaction the less certain you can be about the energy of that reaction. So if we want to create a particle pair ,something that would take energy, the time of that reaction could theoretically be determined with a very small error as to allow a large uncertainty in the energy needed for creation of the particle pair out of nothing.  The particle pair needs to be a matter antimatter pair since we want the amount of charge created to be zero and the amount of mass of the two particles to be the same. If we create this particle pair with a high initial velocity we need them to go in opposite directions so that the amount of momentum is zero. If this pair is created near the Schwarzschild radius of a black hole one of the particles will fall into the black hole while the other particle might escape, causing what is known as hawking radiation. Since we can’t create energy the energy of the emitted particle needs to come from somewhere, and where it came from is the black hole, so due to hawking radiation black holes lose energy which causes small black holes to evaporate rather quickly.

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