gravity is a external force. imagine you have a peace of paper if you wiggle it the gravity starts to cave. when you bend it all the way around the gravity start to break in on itself so it causes itself to make a worm whole but as soon as it makes one it closes instantly because the mass and the weight of the gravity is closing it. if you make the most strongest nuclear warhead and you detonate it in the Mariana trench the power wont come out of the water instead the pressure of the water will fight it and when the fire power gets weak it dies of.