Hi, I'm curious about What world it is, What happend to the initial world to become this state. I'm student undergraduate and I got admission from plasma laser lab of graduate school. But i want to learn about String-Theory. So i planed to learn relevant subject step by step. But What subject i need to learn to be qualified to learn String Theory? Shoud i learn all theory such as QED,QCD,QFT? Is there other mathemetical subject we need to learn? Please lead me into right direction! Thank you for your help, World begining explorer!