Why does the aging process slow down near a black hole?

Because of the curvature of spacetime around a black hole, the amount of"distance" a beam of light has to cover is greater near a black hole. Light travels more distance along the curvature of space ( yellow line). read more

According to SR , time will also slow down our biological process.Even if consider you have a normal watch and you are orbiting a black hole then it will also stopped.Because as I described above , the mass of the parts of a watch will increase as you travel near the speed of light or orbiting black hole and that's why it requires more energy to keep running a watch.And you have not much energy.This same we can apply on also a spacecraft.That's why we can't approach at the speed of light. read more

Time indeed slows down around a black hole according to Stephen Hawking. Now this phenomenon happens because of the super gravitational force of the black hole. By virtue of this enormous force the black hole warps the space-time present all around it to such an extent that time around it slows down considerably. read more