Big Crunch
Essentially the opposite of the Big Bang, the Big Crunch is one possible fate of the Universe. If the matter and energy of the Universe are not moving outward quickly enough, gravity could pull the Universe in on itself, collapsing it in a final Big Crunch. It is not yet known whether this will happen to our Universe.
Explore
Four Areas of Science
Inspiration
Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run twice as fast as that.