Leaving the universe

One day the universe will grow very cold and very dark. Stars will cease to shine and the Big Freeze will become immanent. When the universe itself dies, all life will cease to exist. The question now becomes how we escape the cosmic doom. 

According to Einstein's equations, there are three possibilities for how the universe may end:

1) Big Crunch - when the expansion of the universe slows down, stops and reverses itself. The galaxies will stop and begin to contract. As the distant stars become closer and closer, temperatures will become very intense in the universe. Stars will eventually all coalesce into a superheated mass, perhaps allowing a Big Bounce where the Big Bang occurs once again. 

2) Big Freeze - The growth of the universe continues unabated. The matter and heat in the universe become more diffuse over time with the second law of thermodynamics, the principle that entropy always increases in a physical system with time. The universe would eventually grow cold. Stars will cease to shine and the night sky will be black. Temperatures would approach absolute zero. 

3) Big Rip - Distant galaxies move away from us eventually so fast that they exceed the speed of light. These galaxies disappear from view. This does not violate special relativity since it is space itself that is expanding faster than light. This exponential expansion eventually becomes so great that it is not only the galaxies that are ripped apart, but the very atoms that make up the stars and planets in their respective systems. Matter does not exist in the final stages of the Big Rip. 

Opening a wormhole with a particle accelerator the size of asteroid belt

A sufficiently advanced civilization could build a particle accelerator the size of an asteroid belt. Gigantic magnets would be guiding these proton beams in a circular direction. The way this would work is that each time the beam of protons passes a large magnetic check point on the belt, it would gain energy. When the accelerator has reached the Planck energy, it should provide enough energy to open a wormhole. A wormhole should open when this energy is focused on a single point.