That might be true from my own frame of reference but not so to an observer, right? How can we say there are 3 spatial dimensions at all if what you say is true? What you’re describing suggests there are an infinite number of dimensions based on the different frame of reference for all observers. Why do we then believe there to be 3 dimensions? Is this just one of the cases where 3 dimensions is a useful model for calculation but not really true in reality?

Undoubtedly there must be something I’m missing here—I’ve taken physics courses but clearly I’m no expert. :)