To put it bluntly: A graduate admissions committee will (in my limited experience and pragmatic view) really be looking for a "mercenary" that will be doing research for it's faculty in return for a measly stipend (+ tuition coverage) for a limited time.. eventually completing a project and hopefully moving on to a successful career (making the degree-granting institution and it's faculty look good). So you also need to have some research experience before applying to both show off some skill in the area... and to let the committee know you know why you want to attend (they don't care about your romantic views on physics, and PLEASE don't put that in your personal statement -- be professional: you want to attend to do research in X or Y and become an advanced researcher within academia, industry, or a national lab).