I don't know much about physics but just had this idea: As I understand it the HUP prevents good accuracy of a small object's momentum and position at the same time. Assume trying to measure the momentum and position of a single atom. In theory, can't we get a very good idea of both of these values by first measuring the position and then, (almost) 1 Planck time after, measuring the momentum? If not, how about the following: In theory, measure the position of the atom, then go back in time and measure the momentum instead? (I read that backwards time travel is not rendered impossible by the current mathematical models of reality). Wouldn't we then combine the values to determine both its momentum and position? If not, how about the following: In theory, measure the momentum of the atom. Then set up another identical experiment and instead measure the position. Wouldn't this give the momentum and position? Sorry if it is a dumb question.