that is exactly where modern physics is at the moment. it's exactly why we have things like the large hadron collider, quantum theory, M theory, the standard model, the mystery of dark matter and dark energy
Was looking for somewhere to put this random thought I had (without starting a new thread) and this appears as good as any.
Any resident physicists please feel free to tell me how impossible this is, as I'm sure it is.
So 'regular' matter only makes up 20% of what we believe should be the mass of the observable universe. We also don't know for sure why within that 20% there appears to be far more matter than antimatter (I know there are some solid theories on this though).
My random thought was what if......the other 80% of 'Dark Matter' is actually four other types of matter, and at the beginning of the universe 5 completely different versions of matter were formed in equal quantities. Each only interacts with the others via gravity, and cannot distinguish between the other 4 types, it is just 'my type' & 'not my type'.
Within each type would exist their own versions of forces, 5 types of electromagnetism, 5 types of strong and weak nuclear forces, but only interacting within their own types. Except gravity of course.
You could also imagine that the balance of matter/anti-matter works out in the bigger picture. 'Our' matter is countered by one of the matter versions being mostly made of anti-matter.
Each galaxy could be 5 galaxies in one, with each of the 5 wondering what the other 80% is made up of. Could there be type 2 stars fusing type 2 hydrogen into type 2 helium? If a type 4 photon doesn't interact with our type, we wouldn't know if a type 4 star is shining somewhere in our neighborhood.
You could write a really good sci-fi story around that I reckon...