text: It could be possible, although I doubt if you could actually replace relativity with some other theory that could allow that. So for now it's not possible maybe in future. \nI believe that because think about it before relativity we all thought that time was constant. \n\nPlus even if we can't reach speed of light, we might be able to get close to it which can let us travel farther cause of time dilation. I don't think you could go back in time though.