Related to this thread, but starting a separate one so as not to derail it:
Say someone shows up in our world and claims he’s from the year 2200 and got here via time machine. You can hardly understand a word he’s saying; it sounds like English but also like utter gibberish. His attire is completely different than ours.
What would he have to say/do to convince you that he really is a time traveler and not some extremely eccentric individual born in our time? This individual is only an average person from his future era, not some scientist or engineer, so he can’t truly explain how the technology of his day works any more than the average American could explain how a television, computer or nuclear reactor works.
He tells you the outcome of a few elections or big events in his era, but he can’t recall who won the U.S. presidential elections from 2020-2040 any more than the average American today can recall who won the presidency from 1820-1840.
If his speech sounds like utter gibberish but also like English he would have to have a good explanation for why his speech is so different. If one of us was sent back to 1840, or even 1740, the people of the time might think we spoke a little funny, but they would easily understand us. English hasn’t changed anywhere close to that much in the last 180 years, and if anything the pace of change continues to slow down. For his speech to be that radically different would mean some kind of apocalypse where mass communication had been disrupted. I’d want details on how that went down.
Here’s a thought. A genetic analysis would show that our “time traveller” is distantly related to a lot of people from 2020 - but not closely related to anyone at all. We can’t find anyone who could be his mother, father, brother or first cousin - but lots of people who could be third cousins - and most of those aren’t related to each other. In fact, John Smith appears as closely related to our time traveller as a third cousin, but Smith’s full sisters and brothers all are less closely related to the time traveller. This is consistent with Smith being an ancestor of the time traveller, and is not consistent with any other kind of relationship
He could sing a few dozen songs that haven’t been written yet. This would not be conclusive, but it would be strong evidence that he is either a time traveller or a musical genius.
Give me next week’s winning lottery numbers. Or just give me a few million bucks. Do something for me and I’ll believe him. Otherwise I’d have nothing to gain in believing it’s not some elaborate hoax.
Ask him what “enabling breakthrough” allowed time travel to even be possible. He may not know the specific technical details, but he should at least be aware of some general finding that allowed such travel.
Ask him why he is here.
Anyone who would choose to travel back in time would understand the risks of disrupting the timeline, and therefore the potential to change how the future turns out.
Anyone who was sent by accident or against their will, would understand that our safest course for being able to achieve time travel in the future would be to kill him. And he would be accepting of that.
If he chose to travel back in time, ask him 1) if he intended to return to the future, and if so 2) how.
Ask him if he chose to only travel say 10 years in the past, what would happen if he were to meet his younger self.
If they first stopped a period of time after (in my time stream) than when we met, bought a newspaper or other somewhat complex artifact that hadn’t been produced yet, left it with me, then came back the day after it was produced so I could compare what he dropped off vs what I got myself. I have a vague memory of this being part of “Quantum Leap” but I never got into the show, so any theft is unintentional. Or they could provide a list of notable events for the next few days (e.g. the president says X on Y date, there’s a fire in a particular location at this time, this person dies on this day, etc.) .
For my part, I’d be sceptical but open-minded at first. he’d probbaly need time to convince me.
First I’d look at his clothes (you mentioned attire). I’d expect these to be wildly different from anything we have at present, so that would provide prima facie evidence. Experts in fabric might be able to show that the material cannot be made with current technology. Of rouce, the person could also simply wear cotton or wool without any futuristic processing.
Then Id like to grill the person, probably not about technology, but simply abiout daily life and culture. EVen average persons have a vast implicit knowledge of their culture, and by reconstructing this you could get a fair idea about what the future would look like, even if you can’t reproduce or predict anything clearly. If the person is a fraud you would expect to quicklyl encounter limits in knowledge.
There’s nothing he could do to convince me short of demonstrating his time machine to me. (Take we to 1965!) The very fact that he can’t explain how time travel works would be enough for me to write him off as a crank. Time travel is as unlikely to me as magic. What would it take for someone who dresses and talks funny to convince you that they are a wizard?
I am told that time travel, faster-than-light travel, and anti-gravity all violate the same section of Einstein’s theory. Does he have a flying car, or a jet pack?
An interesting puzzle. A cigarette lighter was unknown in 1800, but it’s just a combination of a flintlock and an oil lamp, so it would not impress anyone. A smartphone does lots of impressive tricks, but most of them require a connection to data from an outside source.
Taking and showing pictures with a smart phone requires no outside data and would utterly amaze someone from 1800.
Similarly it’s possible that some one from the future has a simple everyday object in his pocket that could do unbelievable things that we can’t even currently describe.