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by joshspankit 1623 days ago
There are some rather compelling theories positing that ancient Egyptians discovered how they could make a type of glass that they moulded in to a lens at least 5M in diameter. At that size, the focused light from the sun gets hot enough to melt granite (among other things).

I thin you’re right that they likely would not have had the clarity to make those smaller optics useful, but it feels interesting enough to add here.

1 comments

Got any links for this? I'd like to know more.