I think by those standards it would depend as much on persuasiveness as anything else. It seems really hard to differentiate between “from the future” and “from

I think by those standards it would depend as much on persuasiveness as anything else. It seems really hard to differentiate between “from the future” and “from somewhere else more advanced”, especially with your constraints. Even if you loosen some of the constraints it’s hard. You could show up with a Jeep and some people would think you’re from the future and some would think you’re just from somewhere else. Even if your predict their future that may not convince someone! Predict an eclipse and they might say eclipses are predictable (of course, they’re right), predict the outcome of a battle and they’ll say you can see the future but that doesn’t mean you’ve been there.