They're separable by experimental verification. The laws of physics are multiple orders of magnitude more accurate than the laws of economics, and the physicists are certain that at least one of their models is wrong.
Try getting an admission like that out of an economist!
As economists we are certain all of our models are wrong! But some can be useful in a constrained environment to answer specific questions, so thats why we have so damn many of them!
Try getting an admission like that out of an economist!