dark energy

When Einstein was putting together his theory of general relativity (gravity) he ran into the problem of why hadn’t the whole universe collapsed long ago. You had all this matter in the universe, all of it attracting each other so why didn’t it all result in a big ball of mass? He didn’t have a good answer for this so he came up with the cosmological constant which was that along with the attraction mass had for other mass there was also a repulsive force, the cosmological constant, which kept the universe from collapsing into itself. It was basically a fudge factor, he didn’t have any proof for it except that the universe hadn’t collapsed into itself and there must be some reason for that. He was never very happy with it, but it was all he had.

A little later Hubble discovered that almost all galaxies were receding from our galaxy, and receding from each other as well, so the fact must be that the universe was expanding and working backwards from that they came up with the big bang which explained nicely why the universe wasn’t collapsing on itself and Einstein was embarrassed that he had ever invented the cosmological constant. He called it the greatest mistake of his career.

It took awhile for the big bang to be accepted. There was still opposition to it in the science world when we were in high school. The opponents came up with theories of some other reason why the universe wasn’t collapsing on itself and was not expanding either, but none of them were very good, and they all gradually faded away.

There was some debate about the fate of the universe. Some scientists thought that eventually the power of gravity would overcome the power of expansion and the universe would indeed collapse on itself into an infinitesimal point just like at the beginning of the big bang, which would probably result in another big bang, and this cycle would repeat itself throughout eternity. Others thought that the powers of expansion and gravity would be equal and the universe would settle into a steady state and this would go on forever. And some thought that the power of expansion would be greater than gravity and the universe would become less and less dense and eventually we would not be able to see any other galaxies.

Why would the galaxy hang together? I’m a little weak on this, but I think that the expansion takes place in the empty space between the galaxies where there is not much mass, and a mass-heavy area like our galaxy is immune to the expansion.

But scientists have been probing with their telescopes and computers and discovered that the universe is expanding far faster than they thought it was and the power of expansion is accelerating. They don’t know why, but it is, and they have named the force that is accelerating the expansion dark energy. It’s just a name as far as I know, it is not energy in the sense that electrochemical and the nuclear forces and gravity are.

The theory currently is that this force will eventually attack our own galaxy, stars and planets will be hurled from the galaxy and then they in turn will break up into smaller masses and finally even the subatomic particles will be blown up and eventually we will just have this thin energy field pervading the universe, growing thinner and thinner all the time for, well I guess eternity.

This is what I have been able to take away from what I have read. I think it is substantially correct, but I could have some parts of it wrong. If you did your wiki research I would be interested in what you took away from that.