So I was looking up some stuff on the supposedly haunted/ufo-infested Skinwalker Ranch (fringe stuff as far as many of you are probably concerned) and there was talk of beings from higher dimensional space as possible culprits.

That got me wondering and put many questions into my mind. Would matter from a 4-dimensional universe even be *capable* of interacting with our 3-dimensional world? My personal guess so far is that the answer is either "no" or "only with difficulty/certain methods". Obviously, I mean 4 dimesions of space (not worrying so much about the dimension of time right now).

In order for us to see something, light has to interact with an object in some way. If a piece of 4D matter passed through our 3D space, we could only see it if somehow photons could interact with it. To me, that seems unlikely. Could 4-dimensional matter absorb/reflect 3-dimensional energy from light? Wouldn't there have to be some analogue to atoms in the 4th dimension in order for that to work?

I know that some things are necessarily different in 4 dimensions. The inverse-square law that affects the rate at which radiation and fields lose their strength is a product of the fact that we live in a universe with 3 dimensions of space. In 4 dimensions, that strength would fall off at a faster rate since there would be more directions for the light rays/field lines to spread into. I think it's something like...an inverse-cube law? I can't remember what it was. However, what I DO remember is that supposedly atoms as we know them would not be stable in a universe where the field strength dies off so quickly. What consequences would that have for such matter? Would only degenerate matter exist in 4 dimensions?

What about subatomic particles? I have a feeling that the spectrum of particles itself might be different and is somehow linked to the number of dimensions of space and time but that is just speculation. If I recall correctly, the majority of the mass of the proton comes from the motions of the quarks inside. Since there is more space for the quarks to move around in 4 dimensions, might the 4-dimensional analogue of the proton (if it did exist) have a different mass than our proton?

If a four dimensional universe existed, how would we detect it? Would we be able to detect it at all?