Ok so I figured out what "dark energy" is while smoking. It's what happens when you attempt to measure something in a non-intertial frame of reference, from an intertial frame of reference. It's the Coriolis force, or the centrifugal force, applied to a rotating universe.

Sadly, google seems to tell me I'm not the first person to have this idea. Doesn't look like I'll get to reject that Nobel prize anytime soon.