Question

What will happen if the universe stop expanding? Explain briefly.

Answer 1

If the universe stopped expanding, gravity would dominate the Universe and pull it onto a Universal centre of gravity. After some time (like, a few millenia), the Universe would be compressed into a very small size. Eventually, it will get denser and denser and hotter and hotter. Finally, it will collapse onto itself and become a black hole. This is the Big Crunch theory, the theory regarding the end of the Universe.