How do you keep it 'real' in physics? Seems like some of the directions of modern physics are going into higher and higher dimensions like string theory for example. There's so many crazy sounding theories out there. How do you know identify a down to earth, well grounded theory from something that's 'crackpot' or 'cranky'? I'm thinking about studying theoretical physics, so this is an important issue to me. I guess i'm asking about what are the axioms of a well grounded theory. From my very limmited understanding, a few such axioms might be: - a theory shouldn't lead to contradictions with itself - a theory should begin by stating the assumptions it makes Thats about all i know so far about keeping it real. I'm tempted to add that, a theory shouldn't be drastically at odds with current scientific 'consensus' i.e, it shouldn't say that GR is wrong, or that other well proven theories are wrong. BUT i'm hesitant to write that because, that would rule out all revolutions in physics as being cranky until they're proven.