Your using real world physics here, but you forget about how much perception affects things. Additionally the Cosmere functions with rules different to our own last I checked we didn't have a cognitive realm. Theoretically this could function with just spiritual attributes but that seems unlikely that Brandon would only have four when Cosemere is big on 16.
Of course it's simplistic and will probably have to be torn apart as we learn more, it's the first of it's kind(that I'm aware of). If we suddenly found another Universe bordered our own we would have no way to tell how exactly anything worked there, we could theorize but until we made a major breakthrough into instruments of technology that right now we would think of as mystical, we would be left with that speculation. I can't synthesis years of research or make actual tests but this is what I have.
Mainly trying to unify all magic because let's be honest if Brandon has more likely than not figured that out. Also thinking along the lines of MIstborn, Stormlight, and Dragonsteel, forming the Cosmere backbone; and we found out about Spiritual attributes in Mistborn, and Surges in Stormlight(technically I think that's where we got the three realms from so maybe that's what we we're suppose to take away) and I believe Dragonsteel will introduce the final two pieces.