I think the first thing I'd like to do is travel back in time and introduce antibiotics or warn of planned violent attacks on Americans.
Maybe somebody from the future beat you to it. ;-)
"I think the first thing I'd like to do is travel back in time and introduce antibiotics or warn of planned violent attacks on Americans."
Read a lot of "alternative history" stories in my time.
Go back to, say, the Civil War and introduce antibiotics to save all those who died of their wounds . . . . the sooner anti-biotic resistant bacteria evolve --- at a time when science was not sufficiently advanced elsewhere to cope.
Or a pyschopath lives and does whatever.
Or the South Wins, and the North joins Germany in WWI . . . etc.
Or you warn of 9/11 and, as a result, we don't have the national fortitude to invade Afganistan/Iraq --- OBL and Saddam get an atomic bomb and nuke NYC, instead.
Etc.
Big believer that God uses that bad in the world for ultimate good.
(Of course, He could be allowing time travel, which . . . )