I’d give laser pointers to Neanderthals. Even if they did figure out some useful application for them (maybe hunting?) they’d run out of batteries eventually.
A coke bottle
Drop it from an airplane. Bet they would then say among themselves:
God Must Be Crazy!
After further consideration, I would also give them a Solar-Powered TV that plays nothing but a Video of Hatsune Miku doing Fortnite Dances
A cube of pure tungsten. So when they pick it up they cant believe how heavy it is.
Those little Roman devices nobody can figure out.
Imma come out and say it: they’re old timey versions of copper coils or orgonite pyramids. Gnosticism got kinda big for a while and people were buying curses and prayers and stuff from people to write on little bits of broken pottery like little curses you’d write on scraps of paper in middle school. Somebody out there figured out how to weld little metal sacred geometry figurines and people were buying them because they look cool and some of them probably thought they’d resonate with the vibrations of the universe to cure dysentery or whatever.
I figured it was a game
Antikythera mechanism?
That’s Greek and we have a pretty good understanding of them.
I think the person you’re replying to is referring to these odd little dodecahedrons that we keep finding in former Roman provinces, but for which we’ve found no documentation as to what they were for, if anything.
No, those little dice things nobody can figure out at all. They’re octagonal with a little ball on each corner.
It’s how the Greeks played Minecraft.
Sharpies. Think off all the confused scientist that have to explain sharpie marks under acient paintings.
To fuck with? Contraceptives, obviously!
rip
I always thought it would be funny to take aluminum foil back in time to see the reaction. I mean, imagine if a time traveler showed you a roll of platinum that they use to bake cookies. That’s basically what aluminum was for almost all of history.
A copy of Windows Vista
Nuclear bombs.
That would fuck with them so hard.
Slinky
Rubiks cube.
Meth
Go to that greek dude who invented the steam engine and give him the idea to make a train
Humanity - civilised Greeks or not - didn’t have the metallurgical knowledge to be able to build locomotives and rails out of strong enough materials yet. Ancient Greece basically coincides with the Bronze age.
You’d have to not only bring (knowledge of) steam locomotive tech, but also every single bit of iron tech required to build one. You could skip the requirement for rails by opting for a steam traction engine, not a full locomotive, but those are far closer together in technological ability.
None of this factors in the propensity for steam boilers to explode, which you may or may not consider important.
There’s a reason we were still using beasts of burden (horses, oxen, etc.) for traction until the 19th century.
Advanced maths and physics textbooks
Toothpaste. Try making that out of saltpeter and bronze!