Time travel

I was thinking if I will choose to go back in time if I have a choice because of med school application. Some schools express concern of my low undergraduate GPA. I understand their concerns but feel frustrated that they focused on something that I have no control over anymore. Thus come the topic of time travel. Will I go back to the beginning of my college year and do it all over again with all the knowledge I have right now? I am not sure, the things I scare the most is losing all the friends I have right now. Before I head into college, I have two good friends, Christine and Olivia. Since College (and work and graduate school), I met so many other great friends that I am not sure if it is worth it to lose them. Plus, who says I won't make other mistakes. It's kind of interesting to think how you will live your life if you have a glimpse of the future already. What do you think? :)