Your question is a bit ambiguous, but I'll try to answer it as best I can. While it is true that science fiction books and movies stimulate our imaginations and provide us with marvelous entertainment, many of the concepts and ideas are unrealistic, and in all likelihood, never will happen.
Take the idea of transporting man through space or time. It involves taking us apart molecule by molecule and beaming us to another place or time and expecting us to be and look like we were before. There've been scientists who've tried to invent such a system, but as of yet, to my knowledge, it hasn't been done. And, to be truthful, I'm not sure I'd want it to be done either, at least not to me! And, I don't like the idea of people just popping in or out at random!
Now, to address the concept of going backward or forward in time: The past is gone forever, the future is yet unwritten, and there's only today. Though I've often foolishly wished I could go back and change something I did or said in the past, I realized the events of the past have made me what I am now. And, I also realize that if I altered the past, I would also alter the present and the future. If we build upon the experiences we've gained in our past, we have to realize that we're shaped by it and have shaped others' lives as well. Aren't there things in the past that we've experienced that are memorable and that we'd never want to change? If we went back into the past and changed one word, deed, or thought, the whole world would be different and I'm not sure I like that idea at all!
As for light sabers, photon torpedoes, cloaking devices, and warp speed, scientists are working on them right now and they seem a little less far-fetched.