But energy and momentum are related by the expressions \( \Delta E \Delta t, \Delta p \Delta q \), where the \( \Delta \) conventionally means an interval or range (usually small enough that "locality" makes sense). what is this relation and why do we use it? Or perhaps you can suggest something more realistic? If you can, what kind of test would it be for the Standard Model, or say, just \( SU(2) \times U(1) \) (I guess you have to start somewhere). P.S. In case you didn't know, I'm being sarcastic. In a very droll, correct sort of way.