One of my favorite movie quotes is from the original Willy Wonka and the Chocolate Factory. Gene Wilder, who plays Willy Wonka says "Oh you can't go back that way. You have to go forward in order to go back". To a lot of people that does not make much sense of course you can always go back the way you came. This is not so. In the case of going back in history, we cannot simply just go back.
Going forward to go back actually makes some sense here. 100's of years ago, When Issac Newton first understood gravity the technology was very primitive and due to the advancements in technology we are able to go back and say that he is right. The same advancements in technology also let us look back to Columbus and say that he was not insane for thinking the earth was round. With out these advancements and going forwards in technology we would never be able go back.