OK scenario. You are transported back in time, lets say to 1902 perhaps a little earlier. So your there you have fitted in with the era and now you have the opportunity to invent something that you had in the 20th century, a food, a device, because you are armed with the knowledge of everything that has happened. You could find and take credit for a finding you know they haven't discovered yet. So would you and of so, what would it be??
I would probably invent the Internet, but still give credit to those original innovators that brought it to reality in our timeline. Main reason because since I can live without it now, I won't be able to live without it back then (assuming I'm stuck in that time period).
I would use my knowledge in the medical field, get a jump on disease that are yet to come, but the downside is, you find a cure for them when they arrive, makes way for more stronger ones, but it is worth the effort i would think
That's actually a great idea @Mozzie. But then, some diseases like HIV or AIDS didn't surface until the late twenty-first century, so you can prevent them from ever existing altogether.
In comparison to your proposal, mine seems a bit selfish kek.
But then you would have to invent the Wii U or similar device, NFC support, and video games compatible with those toys. Not to mention, the only reason that the amiibos were popular stemmed from the fact that each character had a large fanbase, which wouldn't exist in 1902.
I would invent the assembly line and the idea of mass production and make it rain with all the cars I'd be producing. And then invent the concept of propaganda and public relations to make even more people buy the cars.