Most people usually consider killing Hitler. But if you think about it, there are on average 80 to 30 million sperm in a typical ejaculation. So I'd find Hitler's dad on the street, bump into him and jiggle his nuts a bit. Then I'd come back to see how much history I changed.
Ship my ass far, far into the future to satisfy my biggest piece of curiosity, probably in 100 yr increments or something. Hopefully somewhere with really good line of sight over a wide area, so I can see some "civilization". If it gets really nice, I'd stay. I can try to sell the machine if funds are necessary.
If it isn't particularly nice at some point, there's a nonzero chance I might die on one of my jumps. Avoiding that, I'd jump backwards again far enough to live out my natural life in the most advanced time I can.
Amusingly, despite being a bit of a history buff, I'd have very little interest in actually going back. Even to learn.
I'd first take my time and study how it works and how time itself works, then I'd study a bunch of history, and a bunch of science, once I'm done I'd go back in time to 1,000 BCE Yukatan Peninsula and chill in the beach, meet some locals, have a good time.
And after your holiday you return and find the history books changed to Columbus discovering a nearly empty continent in 1492 and a archeological record of a big, continent wide pandemic, killing nearly all of the humans. Countless civilisations crashed by mass deaths…..
I have to counter this by saying, I don't think one got would kill an entire continent, specially cuz I am immunized myself to modern diseases, if anything I'd probably help the locals get immunized with technology.
Guess I'd hop into the future to see how stuff plays out, then to go to the past and fix stuff. Then go back again because I realized the folly of time travel and must stop future-past-me from creating some wacky existence-ending paradox, but the real treasure will be the friends I make along the way and the wisdom I unlock.
Also, I sell the movie rights and retire comfortably.
Probably just see some historical events happen, like the signing of the Declaration of Independence, Apollo 11, etc. I wouldn't really want to mess with anything to keep the "timeline" safe.
Go see Nikola Tesla with a smartphone and take pictures of his work (with his permission), granted you could travel back. Priceless.
Could also tell him how much he shaped the world we live in today with every mobile phone using technology he created (wireless). Although that might break the matrix, who knows.
Would probably (read: definitely) ensure that I have a PC that is not described as an absolute pos in 2009, when I first heard of bitcoin and gave up because it just wouldn't run.
And after your holiday you return and find the history books changed to Columbus discovering a nearly empty continent in 1492 and a archeological record of a big, continent wide pandemic, killing nearly all of the humans. Countless civilisations crashed by mass deaths…..