You never see time travelers use salt in get-rich schemes, but for a few bucks at the supermarket you can have salt of quality and quantity rarely seen in the ancient world. Show up to feasts and just hand the salt around. Make it rain salt. You'd be able to get plenty of shiny rocks for that.
But no, time travelers always bring gold. Never salt. Despite the fact that "salary" literally comes from the Roman word for salt.
Basically, go back in time, bring salt, exchange salt for worthless trinkets, return to future, make a killing on the antiquities market.
For that matter, show up with some stainless steel. Or what about aluminum? The ancient world would go apeshit over aluminum.
And that's saying nothing of going back in time and being a wizard because you remember a little calculus from high school. Hell, the concept of zero and Arabic numerals would blow their minds when used at the right time.
What about going back in time and bringing refined sugar? You could print your own money.
But no, they always do the boring thing.
@intransitivelie the "being a wizard" thing was covered over 130 years ago by Mark Twain (A Connecticut Yankee In King Arthur's Court). Very entertaining, would recommend.
You'd need a huge quantity of salt to match the value of a handful of gold. Lindybeige did a video on that.
... you're right about aluminium, but you spelt it wrong :P
@intransitivelie The sugar one was probably your best bet tbh. Other spices (cinnamon? ginger?) might also work. And you wouldn't want to flood the local market for any single commodity.
You'd want to make sure to warn your customers that your spices are stronger than they're used to — most lost a lot of their flavour/pungency during transport so their recipes call for quite big quantities which with fresh spice would over-flavour the dish.
As others have said, pepper might be the best choice
It's cheap now and expensive then. But excellent point about the potency.
a Schelling point for those who seek one