I have been wondering about speed. If we are sitting here on earth rotating around our axis at approx 1000mph and orbiting the sun. And the sun is orbiting the Milky Way and the Milky Way is spiraling out from the center of the universe. How fast does that mean we are moving? And of course being the inquisitive person that I am I wonder when we are talking about light speed are we meaning relative to a fixed object and if so which one? The center of the universe? I guess the reason I am asking is because I am interested in theoretical time travel. I believe it is possible to if you can some how move past the speed of light and and then be able to instantly get back to the object you left from. I don't believe it is possible to comeback however. Unless there is some fundamental flaw in our understanding of time and light. Anyway I am not a physicist I am just very interested in this kind of subject matter along with history. So if my questions are too basic forgive me.