ok, i was just thinking of something... einstein's relativity says that one may not travel faster than the speed of light, which is c. Now consider the speed of light in some other medium, say water. In water, the speed is c/n (n = refractive index of water, n > 1) Now, suppose i am in water and am trying to measure the speed of light. will i measure c or c/n.. and suppose i'm running in water. Then can i go faster than the speed of light in water. i.e. can i move faster than c/n and yet less than c??? if i can, than how will that ray of light look to me?