The Expanding Universe

Where to from now? further out, I suppose. But then where??

I am pretty sure I remember reading. Ah, now, if Dark Matter is real, its going to stop the Universe from expanding [at some point], then the energy from the Dark Matter will collapse the Universe on itself. But correct me on this. I only remember so much!

Nobody knows.
The most widely accepted model is that there is a force called dark energy that gets stronger as things become farther apart. So expansion will speed up faster and faster until 'The Big Rip.' This is the point where atoms are torn apart and the universe becomes infinitely diffuse and absolutely cold.

There is also the possibility that the universe will recreate itself at least according string theory. Check out cyclic model of the universe its a newer and a bit controversial theory.

But yea dark matter and dark energy have basically been put into cosmological models because they couldn't explain why galaxies can hold each other together (so they made up a type of matter) and couldn't explain why the universe's expansion seems to have started really fast and then slowed down (so they made up dark energy which is kind of an improvement on the idea Einstein had called the cosmological constant).

Personally this kind of filling in the blanks with things that you have no direct evidence for I find uncomfortable. I think all cosmologists do too. There is hope for new data though. A satellite is being built that may detect gravitational waves which is they exist and are detected points towards one theory or the other (infinite expansion or recycling). Also the LHC should give more clues if they ever get the damn thing running.

I think these ideas are uncomfortable because they are purely phenomenological, not because they are purely theoretical. We can measure and map dark matter and dark energy fairly accurately but nobody has proven a structural/mechanistic theory to explain their existence and their action on atomic matter.
There are hypotheses out there and I'm way excited about the LHC.

I'm betting on a big win for the quantum field theory. Reality is a bunch of interacting fields. The fields have different properties so they propagate different types of waves. All matter and energy is built of different combination of interacting waves. Every particle is just a ripple through a different kind of field. So matter is made up of tons of interlocked waveforms propagating through their own fields.

If quantum field theory is true then dark fields are maybe not so exotic. Maybe dark matter is a condensation on the (hypothetical) mass field without some of the other waves that usually make matter extended and shiny. This is gonna be tested at LHC, quantum field theory makes some weird predictions about the mass particle.

Dark energy is totally boggling though! It is a force that causes repulsion between masses only at extreme distances! That's effed up! Really hard of bring it into the lab because it is only detectable between masses that are hundreds of millions of light years apart like galaxy clusters. It is pretty clear that there is a force and that it's strength increases as the distance between two masses increases but nobody really knows how that can work.

I love this stuff. Wish I understood it better.