The whole world would be in total chaos if it exists. Think about it, if someone could travel back in time or into the future, the history would be twisted and messed up. Your ancestors, you , your future generations wouldn't exist if someone changed history. Basically, everything you do right now, your decisions, your next action in the next second could lead your life in a different direction. So, I personally hope time travel wouldn't exist and even if it did, I hope no one will ever use it. :) And to answer your question, no , I do not believe in time travel.