Hello PF, I have some questions which I cant get an answer, and everything I think is based on intuition and not on knowledge. These are not HomeWork questions, I don't even study relativity in school. 1) Michelson and Morally experiment showed that there is no ether right?? so relative to what is the speed of light measured? or It's absolute speed? What is absolute speed?? so basically there is no medium that the light travels in it? it just travels in nothing ? 2)Time deletion: How does the height affect the time? If I understood correctly if lets say You're on the top of a mountain , and some one is waiting for You down there , the clock down there will tick more slowly than the upper one , but I was thinking, as You go up your linear speed increases (v=wR,w=const R>>>increases) so the clock is moving(higher velocity) faster -> should tick slower? what am I missing?? 3) if some 1 can just point out what is the main difference between special and general relativity i would be very thankful(just main difference). Thank You in advanced! Dweirdo. P.S Any web source for reading more would be appreciated although I have most of them i think, so just name it so I know what is recommended. thanks.