How soon can you start doing research at RPI? Will you be able to skip intro Physics classes due to AP/IB credits and start taking upper level classes sooner? A big part of getting into a Physics PhD program(apart from the obvious high GPA) will be research and the Letters of Recommendations you can get from professors. Many schools will expect you to be at a certain level classwise before you can get into research so the sooner you get there the better and the more time to cultivate those relationships for your LORs.