Step 0: Be Ed Witten. More generally, if you can get into one Ph.D. program you can probably get into most of them. Profs, like any employer, want the two key

Step 0: Be Ed Witten. More generally, if you can get into one Ph.D. program you can probably get into most of them. Profs, like any employer, want the two key things: be smart, and get enough done to justify their investment in you. Except that students are really cheap, especially in the first year or two, and especially in math or theoretical physics where their cost is mostly in office space, ever-cheaper computer time, adviser hours and coffee.