It's in a black hole that the time dilation happens. Black hole is this kind of matter where it holds a huge amount of mass in a little space area. If Earth was turned into a black hole it would roughly be the size of an orange. But it would still have the same mass. Because of this reason and many other reasons which involve mathematical calculations, a black hole has a very strong gravitational field. A gravity so strong that when you approach it instead of pulling you in, it pulls your atoms apart. If you get in feet first it would pull at your feet faster than your head so it stretches you more and more until you snap. And it will keep on to break your molecules too. Black holes are so strong that light thrown into a black hole at the speed of light (the highest speed in the universe) will travel further tham any molecule but still won't reach the center of the black hole. The gravity will negate the velocity of the light and stop it. That's why it's called a black hole. Because even light can't penetrate it. And it is unknown what lies within it. There are many theories but that's what they are. Just theories. So, only the laws of gravity work here. Meaning even time is forced to take a halt. That's what Einstein's theory means. You get in(impossible so far)/near a black hole and stay for a few years to go back home and see decade had passed. Ene engdih mawkatn new yalkuh. Physicistochu degmo bedemb ena betam yasbubetal. For more info YouTube lay StarTalk yetebale arif channel ale. Sle black hole and dark energy and Einstein's theory and many other topics arif discussionoch alu