Astronomers have known for some time that the universe is expanding, but until very recently, it was always assumed that after the Big Bang, the material in the universe: stars, nebulae and galaxies, we basically just sort of thrown out there, coasting from the force of the Big Bang.

It was never clear from the observations of galaxies and their redshifts, what would happen in the long term future of the universe. Would the expansion of all the galaxies slow and eventually stop? Would the gravity from everything in the universe cause a Big Crunch where everything started falling back in on itself? Or would everything just keep going?

Regardless of which of these scenarios actually played out, Big Crunch, keep going, stopping, one thing was pretty much assumed to be true in all cases: the expansion would be slowing.

Astronomers were so sure the expansion of the universe was slowing due to the gravitational pull of all matter in the universe, that one of the great ironies occurred when one of the projects that actually discovered that not only was the expansion of the universe NOT slowing down, but was accelerating, was actually called

"THE HIGH-Z SUPERNOVA SEARCH : MEASURING COSMIC DECELERATION AND GLOBAL CURVATURE OF THE UNIVERSE USING TYPE Ia SUPERNOVAE".

Available here:
http://arxiv.org/abs/astro-ph/9805200

Imagine their surprise. Here's their first paper: http://arxiv.org/abs/astro-ph/9805201

No one really knows what's causing the acceleration, but there are a lot of people, myself included, trying real hard to find out.

Spacetime is getting bigger all the time, more of it is produced every second, but there is no more new matter being created - only new space. More and more spacetime, same amount of matter - and all of it being pushed farther and farther apart. What could be causing this?

One theory holds that there is a force, an energy responsible for creating more spacetime and pushing everything in the universe farther and farther apart. It's still possible that if there is not enough of this energy that there could be a Big Crunch, or possibly even a slowing and eventual standstill (but that's a relatively unstable outcome).

What I believe will probably happen in the long term future of the universe is that the spacetime between all galaxies will continue to grow and the distance between them will become so great that each galaxy will become isolated. The stars within them eventually burning all of the available hydrogen and helium, the fuel of the universe, until there is none left. The galaxies, lone islands with no others in sight, slowly dimming s their stars become unable to sustaing themselves, no new fuel from which to create new stars.

Each galaxy, a gigantic molecule in the evaporating liquid of an ever expanding spacetime, never to reconnect with any of it's former bretheren.

The universe will eventually evaporate into nothingness.

That's it for now Space Fans, I'll leave you with that happy thought. Have a great Halloween!

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MUSIC:

"Herringbone Sky", Green Man. Available here:

http://www.garageband.com/song?|pe1|S8LTM0LdsaSkZFK_YGg