I think it would be pretty difficult to guess if the gov't had time travel capabilities. If they had, would they go back in time and prevent 9/11? Or would they not use the technology because it would cause a tear in the time space continuum and eliminate things like Homeland Security or the War on Terrorism. Would they be able to weild that kind of authority over nature responsibly? And if so, would we know if they had, or would we just see it as something happened and always was, even though they know it had changed? Heavy topic.