Originally posted by Sihana
My theory about the universe collapsing in on itself comes from the fact that the Andromeda galaxy is falling towards the Milky Way and our local group of galaxies is falling towards the Virgo cluster which is falling towards the Virgo supercluster which is falling towards The Great Attractor.
As well, gravity is still not very well understood even with Einstein's equations. Scientists cannot even explain how stars rotate around in galaxies. Stars on the outer edge of the galaxy will rotate around the galaxy at the same speed as stars towards the center of the galaxy. This is in direct contradiction with how planets rotate around the sun. The outermost planets always rotate around the sun slower than the innermost planets. However, when it comes to stars rotating around the galaxy, they all rotate at the same speed like spokes on a bike wheel. To make this fit into our current equations, we have to make up non-existent stuff we call dark matter. For years people have been searching for this non-existent dark matter because they are so sure that their equations are correct therefore it must exist.
I have my own theories on gravity which is why I think the universe will eventually collapse in on itself. Also the universe is not homogeneous meaning that there is an even distribution of stars throughout the universe. In fact there are vast sections of empty space and clusters of matter. When light travels through space it gives an illusion that the universe is expanding when it actually is not.