You know when people ask hypotheticals like "if you were transported to medieval times, had to live there, and can take one thing with you" and you realize how useless computers, phones, or light bulbs would be? I think my new answer is a bottle of exotically colored dye!
I'd bring my Casio Rangeman. Altimeter, barometer, compass, thermometer and time in a small solar powered package. I'd be able to predict weather and the setting and rise of the sun with greater accuracy than anyone else. Hopefully I could get a job in a kings court as a wizard. Worst case I sell it for a mansion.
Not related to the article, but thanks for connecting some dots for me. My first smartphone was a Casio G'zOne and people still don't believe me sometimes when I say I had a Casio phone. It was basically the only rugged smartphone on the market at the time - gorilla glass, rubberized edges, waterproof. Knowing it was part of the legacy of these rugged electronics helps fill in the gaps of why Casio was making phones and why they were basically bulletproof. I've been buying "rugged" phones ever since trying to fill that hole in my pocket.
Showing up prior to the Reconquista in Europe with a working knowledge of 0 and the Hindu–Arabic numeral system would go a long way. You could probably also figure out distillation. If you aren't too early you could probably invent telescopes, microscopes, and germ theory. And that's without bringing anything other than knowing that those things could exist.
There's probably a good book on practical engineering stuff that would really come in handy. Simple recipes for things like clear glass, gunpowder, interesting properties of coal, navigation, etc.
I think as long as you kept your mouth shut about doctrinal matters, you'd be fine. Almost all of the scientists who go in trouble with the church were busy writing commentary on religious doctrine outside of their scientific work, and that's what got them in trouble generally speaking. The Catholic Church for its faults funded a lot of astronomers and other scientists in the medieval period and into the Renaissance.
It's not the lenses which are difficult, it's clear glass.
With a piece of pure glass, the rest is some emory and a great deal of patience.
Clear glass is also more about knowhow than raw technical difficulty, it isn't the Bessemer process, it's knowing how to flux with soda + add some lead to get the melting point down, then pouring it on lead to get nice flat sheets.
You would make good money by just peddling the bottle themselves for majority of history. Glassware, fine China and other vessels that can contain your dyes are not cheap before the industrial revolution.
No, not that much, they knew how to make glass since way long ago. I guess in the Americas you could, they apparently either had not much glass or it wasn't viable (like the wheel, which was for children's toys mostly).
I've always wondered how things would have played out in the americas if someone had invented something like the Chinese wheelbarrow[1] which is meant to work something like a human powered cart.
And my usual thought is to bring bag full of ibuprofen and peddle that as a pricy hangover cure for the nobility. Truth be told, I doubt I would get anyone to even try my pills.
