Question: We were cut off in the chat. so continuing, I believed that the universe was expanding as a result of the big bang and that it is slowing down because gravity is pulling us back in. and eventually the universe would stop expanding and start contracting and then crush it self into another big bang. But you say that dark matter is pushing the universe out so can you please enlighten me more on that and dose that mean that the universe will never stop expanding.

So you are mostly correct. The belief used to be that gravity was slowing the expansion of the Universe, and would stop it altogether and collapse it back down into something called the Big Crunch. However, the group I work with discovered the the Universe wasn’t slowing down, it was actually speeding up. Something was counteracting gravity. We call this Dark Energy. Dark Matter is something different and unrelated, it is matter that does not have light and can only be detected through its gravitational effects. We are not creative with names, so it leads to confusion.

We don’t know what Dark Energy is. I am currently work on projects trying to find out what it is. Einstein originally came up with something in this theory of relativity, called the Cosmological Constant, that acts exactly like what we are seeing. He wrote it to balance his equation, but thought an anti-gravity-like force was too crazy and left it out. He called it his biggest blunder, however he might have been right after all!

The consequence of Dark Energy is that the Universe will never stop expanding, it will grow faster and faster. One of two things will happen. It will either grow so fast for so long that everything will be isolated, first galaxies, than stars, than eventually even atoms will be by themselves with nothing around. We call this scenario the Big Freeze. The other possibility it will grow so fast it will rip the Universe in what we call the Big Rip.