[SOLVED] Time Dilation-AHH!! So, I feel like this should be a simple problem, but according to my online homework, none of the answers are correct. Here's the problem: A spaceship is moving at 0.66 c (0.66 times the speed of light) with respect to the earth. An observer on the spaceship measures the time interval between two events on earth as 35 hrs. If the spaceship had been moving with a speed of 0.9 c with respect to the earth, what would the time interval between the events have been? So, I used the equation T= gamma*To, and To as 35 hours, but then I thought maybe I was doing it backwards and used the 35 hours as T, and still couldn't get the right answer!! Is the time interval of 35 hours the proper time interval? From what I read in the book, proper time is time as measured by an observer who sees the events occur at the same position, and is this is a time dilation problem, then the answer must be longer than 35 hours. I'm just a little frustrated, I don't know what I'm doing wrong!!