Do physicists really believe in time travel? I'm kind of an idiot so I don't get all the formulae, but it really doesn't add up with my common sense. Allegedly if you slingshot around a blackhole you'll go forward in time. To me this doesn't make any sense, but maybe it's because I'm an idiot.

So physicists are telling me if I manage to go fast enough I'll age slower and end up in the future. Meaning if I find a way to run fast enough down the road and somehow stop instantaneously without the g-forces killing me I can end up inside an Arby's that hasn't been built yet. Can anyone explain this? Am I just misinterpreting the assertions?