To the left is a 3D model of spacetime, the more massive red object leaves a deeper bend in spacetime which attracts the white object.
Astronomy
march 2015
5
So, Black Holes
We’ve all heard of black holes, but where do they come from and why do they do what they do?
Well... Black holes are actually the remains of dead stars that had IMMENSE masses. When a star is ‘alive’, pressure builds up in the star as a result of nuclear fusion, which builds up pressure to counteract the force of gravity. Gravity pulling the star inwards and explosions made by nuclear fusion that push the star outwards act against each other to create equilibrium. When a star ‘dies’, the star’s core loses the elements necessary for nuclear fusion to take place and the force of gravity becomes stronger than the force of pressure inside the star, so the star caves in on itself. One of a few things can happen to a star when it dies, all of which depend on the size of the star: it can die ‘peacefully’ and become a cooler white dwarf, it can explode violently into a destructive supernova, or it can form (you guessed it!) a black hole.
Black holes are formed when the most massive stars (over 20 times the mass of the sun) are crushed down and create a supernova. The remaining mass of the star condenses into a point which has virtually zero volume but with near infinite density. This point is called the singularity and near it, an object would need to travel faster than the speed of light to escape the singularity’s event horizon. This is why black holes appear black, because light cannot escape past them and into our eyes. Because of this, we have no clue what they really look like! Since no object in the observable universe can move faster than light, anything and everything having the misfortune to end up near this boundary will be lost in the void forever.
Previously, I said that objects with great mass cause a deeper gap in spacetime, but black holes, having a near infinite mass, are so massive that they cause deformities in spacetime. If you were looking outward while standing past a black hole’s event horizon (theoretically of course), time, relative to your position, would move incredibly fast. If you were able to return to Earth after spending about 10 seconds past the event horizon, thousands of years would have gone by and humanity would have finally invented the mute buttons on microwaves.
So the next time you build a super ship like in Interstellar and fly over to a black hole and then back to Earth, get ready to tell a crazy story that would revolutionize astronomical studies forever!