I came across this article about a new theory regarding the nature of dark matter. I recommend giving it a read, in part because I think it is good for all of us non-physics types to appreciate how much of the ‘basic’ cosmology we were taught as fact is still under debate. Even things that many of us comfortably treat as real (like black holes) might be artifacts of a mathematical model and the phenomena they explain might be better explained by another model; we just haven’t got all the data in to settle the issues.
Once you break down Spinoza’s binary parallelism of modality, you end up with an asymmetrical and indeterminate modality. It is asymmetrical in the sense that what takes place within one mode isn’t simply replicated within another mode. A small change in the mode of extension may have a dramatic or insignificant impact on the mode of thought. It is indeterminate in the sense that we can’t specify exactly how many modes of substance there are.