I don't necessarily want to go back in time, but I would love to know how to go up and down and from side to side in time.
actually that's kind of impossible. you can't go back in time because time just is, it can't be changed or manipulated. we just precieve time by the things that happen...
Theories: 1) if someone in the past or the present time would have discovered time travel we would know. 2)if someone in the future had discovered , the time machine, he would travel in the past and we whould know... right? 3)in the attempt of macking a time machine/portal the future man had destroied earth