How do cosmologists supposedly simulate Dark Matter and DArk Energy when they have no idea what causes either of those phenomena?

[Wade12345]

I just glanced over an article on MSN about a new simulation for the first billlion years of the Universe, and couldn't help but laugh. They can't prove what Dark Matter is, it may be another particle or it may be something other than a particle or wave. They can't prove and have no idea what Dark Energy is, so how do they supposedly simulate a billion years worth of the Universe with NO FUCKING CLUE what those two variables represent nor what formula those forces use?

There's a motto for any computer simulation:

"Garbage in equals Garbage out."

[slatyb]

They postulate the ways they would interact with ordinary matter, run a simulation, and look at the results.

[Wade12345]

There's supposed to be around 4 times more Dark Matter than ordinary matter in the Universe, yet scientists have not detected a single particle of the substance in nearly 80 years of looking for it.

I don't think Dark Matter is a particle I think it's an entirely different force law, but I could be wrong.

[slatyb]

I haven't done the work that would allow me to have an informed opinion.