"The Big Crunch"
What's the ultimate fate of the universe? Man, you guys ask some pretty heavy questions. I mean, seriously, just a few weeks ago it was fun, light stuff about how shower curtains wave around. And now we're on to subjects spanning deep space and cosmic time. You don't mess around, do you?
The crazy thing about modern physics - and especially cosmology, the branch of science dealing with the study of the whole entire universe - is that we can actually begin to answer crazy, ridiculous questions like "How will the universe end?" The answer is, of course, "we're not exactly sure". But I can tell you what the answer isn't.
We live in an expanding universe, and the amount and type of stuff in the universe affects how quickly it expands. If there's too much stuff like stars and gas and bananas the expansion will eventually slow down, stop, and reverse. Instead of spreading out the galaxies will rush towards each other. Individual objects lose their identity as they crush into the same ever-increasing volume. Temperatures and pressures rise. Atoms turn to plasma. The forces of nature meld into more exotic forms. Everything you know - everything there is - compresses into an infinitely dense point.
The opposite of the Big Bang. Behold: the Big Crunch.
...is unlikely. Almost 20 years, observations of distant supernovae revealed something surprising. Not only is the universe expanding, but it's expanding at an ever-faster rate. We don't fully understand it, but that didn't stop us from giving it a cool name: Dark Energy. It started about 5 billion years ago and doesn't look like it's going to stop. Our long-term fate isn't a Crunch, but a Rip.