Have you heard about the guy who travel back to past from future?

I think that it isn't possible... It isn't because if he is telling the truth, we are living in the past... It means that in an other universe there are us at 1 year old, in another universe there are us at 2 years old,... etc... It means that our past can't die... So, I think that John Titor has find a good idea to become famous!