Indeed. It’s said that Eli Whitney could hear unlicensed cotton gins running in the distance as he sat in court attempting to get compensation from other people using the invention.
Yeah, I would just sell the endless stream of songs in my head for $5-20/apiece. Putting 1820-appropriate lyrics to “Walk on the Wild Side” is the true challenge here. 
Wait till they see my contact lenses! (And without them, I’m not going either. And the liquids to clean and store them. A large supply, please).
ETA: I have often been stark naked with contact lenses on!
I still think that the best answer yet given in this thread is dental work. It’s one of the few bits of evidence you could give to the first guy you meet, right on the spot.
And I think I was the first person to mention that, back in Post 15 https://boards.straightdope.com/sdmb/showpost.php?p=22334011&postcount=15
When I close my eyes, contact lenses are inside of me. Close to the surface, yes, but definitly on the in side.
Hmm, I wonder if I could find a solar-powered calculator small enough to fit inside my mouth…
ETA: I suppose with sufficient warning I could take the strap off my digital wristwatch and hide it under my tongue. But seriously, on the subject of fighting the hypothetical…
I couldn’t prove it, not at all. Still, if there was a portal and I could drag through a back-pack and a steamer trunk with me… who would miss me? It might work nicely!
Then again… you’d be amazed at how fickle the world can be. Would I be where I am today or any any geographic location?
“Yes, I’m travelling to Kallstadt, Palatinate in Bavaria. A family is putting me up in their house while I’m there. Purpose? Hunting. The name of the sponsoring family? Drumpf…”
My money is on the person from the present time using present-day knowledge rather than the unprepared person from the future using vaguely remembered ideas about how things worked before he was born. This would be true just using an ‘advisor’ position, but is even more true of the future person is going to be at the helm since his ability to navigate connections in the modern day business world is almost certainly going to be worse than a present day’s person.
You keep asserting that there are a LOT of such inventions and that a modern person transported back without preparation would be able to consider them. And yet actually listing them seems difficult, and when they are listed even a little investigation typically shows that the ‘general idea’ part was already known decades earlier.
You need to be an expert on the technology of the 1820s to know what ‘low hanging fruit’ you can hope to actually make. Otherwise you make a fool out of yourself prophetically telling people about the basic idea of an electric light bulb which they already had, or trying to test tungsten filaments in a vacuum when you need fifty years of advancements in vacuum tech and eighty in machining tungsten for that to actually work.
Uh-huh. I notice, again, the distinct lack of any specifics of what you’re going to ‘jump right in’ and do. There’s just this assertion that your future knowledge would be really handy… but nothing about what future knowledge would actually do for you. I mean, what game are you even going to be a player at? Name the ‘low hanging fruit’ off the top of your head, and then we can look up and see if it was even low hanging fruit or not.
General knowledge of how most things work is just not of much use in actually making them, and in most cases the ‘general knowledge’ was already well known to people interested in the subject long before making the device was practical. The knowledge that something can be done with future engineering advances isn’t a leg up in making it, as the hard part is the engineering advances. Vulcanization looks like it might actually be something that could have been accomplished decades earlier, and you might well convert the fortune behind the Goodyear Blimp to the Walrus Blimp if you manage to get it working in 1820 instead of a decade later. But the vast majority of things just aren’t, AND most people don’t have any idea which are and which aren’t.
Side-thinking this, in 1820, aluminum was only a hypothetical atomic number, and in 1920, plastic wasn’t even theoretical. The field is wide open for another breakthrough, maybe in 2020. Would we recognize its potential?
People smarter than me, ehe? 
Thing is, they didn’t actually know what would work, but I do. I don’t have to be smarter than they are. At any rate, you have asserted that nitrogen wouldn’t work, but I haven’t seen you actually say why. And nitrogen isn’t exactly the only option. You have also asserted that a vacuum pump wasn’t possible, and myself I’d go with an inert gas as my first try, but I’m not convinced that an adequate vacuum isn’t possible.
And so this means…what? Because it wasn’t discovered until the late 1800’s means basically nothing, as, again, I have a bit of an advantage over those who were looking into this in the actual time as opposed to this fantasy scenario. The key is I KNOW that these things are out there and CAN be found, and they didn’t.
Well, I explained this in an early post. Assuming I survived and could do it, I know, for sure, where there are un-found, at that time, resources to be gotten. I also know what actually got people rich during things like gold rushes. Now, whether I could survive and figure out how to go after them, that’s a valid question…I’m unsure myself. But, assuming I could do what I layed out, I’d have capital to do this other, assuming I wanted too. You are handwaving away a lot, and assuming a lot about my own abilities. I get it. But I think you are overestimating the difficulty and trying to extrapolate that based on the actual timeline. If a wealthy patron with plenty of capital AND even a basic knowledge of what was possible wanted to fund such an endeavor, I have zero doubt they could produce technology decades if not centuries ahead of the trial and error and often underfunded efforts that actually transpired in our timeline. There is no real bar to producing a working light bulb in the 1820’s if you had the funds and knowledge of what was possible. The reason it didn’t happen before Edison was because no one really through the resources at it with foreknowledge of how transformative it would be. I don’t know that this would be the project I’d undertake, but I know if it was it could be done. And you have, IMHO, not really made a case against it, merely asserted repeatedly that it’s not possible.
Even if you’re white, the way people talked back then was very stilted and formal. The more familiar style of speech we use even with strangers today would be offensive to them and get you into a lot of trouble. So someone might get pissed and shoot you, challenge you to a duel, or you just might not be allowed in polite society. Your modern morals would probably also make you persona non grata in all but the most radical social circles.
I’d bring a watch with me if I could go back with you to time how long it took before someone looked at you with outrage and said, “I beg your pardon, sir!”
I’ve lived in houses with no running water, heat other than wood/coal stoves, or indoor plumbing. I’m glad to have those things now; but I certainly wouldn’t kill myself over lack of them.
I don’t particularly want to wear the clothes my neighbors routinely wear; but I wouldn’t kill myself over that, either. Any clothing one’s not used to is uncomfortable; work pants are far more convenient than skirts for some types of work, but on the rare occasions I’m in a skirt I find them in some ways more comfortable than pants.
The rest of that is far more of a point, and may have been what RivkahChaya meant. But I’m just as glad my great-great-grandmothers thought it worth staying alive.
I’d back the one who I thought knew what they were doing. If the one with experience 200 years in the future had the sort of detailed knowledge applicable to the field that was also applicable to the current time, then yes, that would be a large point in their favor. If they only knew as much about the tech of their time and the tech of this time as I know about the tech of this time, while the person born in this time knew a lot about the tech of this time, the advantage would be to the person born in this time. I’d also want to know whether the individual was a scam artist, or a thief, or a total fool at dealing with legalities and/or other people.
I am not convinced of that. We have very little to go on besides written texts, which are, by nature, formal. I believe that argot and casual speech was very common, the stilted formal manner less so. Still, adapting to the manner of speech of the day would probably take more than a day or two.
Of course it was different for your great-great-grandmothers, as they grew up in that world. But imagine you’re a time traveler finding yourself in 1820. You see someone going through what George Floyd experienced, or worse, and can do absolutely nothing about it. Even objecting is going to get you looked at strangely at best, or ill-treated at worst.
That is all assuming you are in the United States and appear to be a white American of English descent.
That just happened to a batch of people in 2020.
Yes, I know, their getting it on camera has resulted in a whole lot of people in the streets, and might (or might not) produce some actual change, eventually. But they were unable to do anything about it while Floyd died.
And there were people in 1820 who were doing something about it. Their efforts – and those of a lot of others since – took quite a while to end slavery, and still haven’t ended prejudice and abuse. But if you did find yourself back in 1820, and especially if you managed to get rich, as many in this thread seem to be aiming for – what would you be getting rich for? Just so that you personally could eat fancy food and be waited on?
This and all other inventions wouldn’t make people think you came from the future, but they would just think that you were a really smart guy that figured out something new. They would think that you were smart while restraining you in an insane asylum for claiming that you were from the future.
Velocity hit it upthread. What would it take for you to believe that the person in front of you is from the year 2220? If he predicted that Biden would win this year’s election, that certainly wouldn’t be enough.
I suppose it would take little details. Suppose someone in June, 2019 came to you and said that starting in February to March of 2020 there would be a pandemic called Covid-19 that would shut down restaurants, bars and other non-essential businesses and kill approximately 100,000 Americans and cause a divide where Republicans wanted to reopen yet Democrats wanted to stay shut down.
All sports were cancelled, and Trump said/was accused of saying that people should ingest household cleaners to treat the virus. Then, at the beginning of June, the world would learn that a man named George Floyd was killed by a Minneapolis police officer by kneeling on his neck and there were widespread protests across the country.
If someone told me that in June, 2019 and I’m sitting here in June, 2020 and listen to a recording of what he said, I’m probably convinced. The problem for 1820 is that we have no real recollection of those events.
Sure I could say that Monroe gets re-elected almost unanimously but 1 elector votes for someone else, but most people would just think that was a damn good guess, not that I was from the future.
jtur88, aluminum was known in 1820. The pure form was incredibly expensive, but it existed, and people knew that it was quite common in compounds. The trick is knowing how to extract it from those cheap compounds economically, which involves mumble mumble LOOK OVER THERE A BUNNY and electricity.
Yes. A historian trained in as many details as are currently known for the specific time and place could probably pull it off – we have a lot of records from 1820, at least in some places in the world. But most people have only a vague idea what happened, and almost certainly some of what they do think they know is wrong.
(And you would need the right place. The person who knows that much about 1820’s Boston, say, but who pops up instead in, say, Dzungaria is unlikely to find their knowledge of much use.)