Not so fast, my friend... (Score 1)

Disclaimer - I found all of this by using Google. I don't know how much of this information is rock-solid, but in the context of a Slashdot post, I think it'll work fine.

It's still a point of contention whether or not Archimedes actually did the burning mirrors trick.

To wit: the earliest source I've found for this information is the Book of Histories by John Tzetzes, in the 12th century. He describes the mirror as a hexagonal mirror, with six square mirrors attached to the main with hinges and leather straps. This way, the mirrors could be focused.

Now, is this accurate? It was written much more than a millennium after the event, so it may have been legend becoming fact. He didn't have a parabola of any kind; I think Diocles was the first to come up with the parabolic mirror (one century after Archimedes), and he wrote about it in the book 'On Burning Mirrors'. I guess it's possible that, over the centuries, people got the work of Diocles and Archimedes a little mixed up (seemingly easy to do, since Diocles based his work on Archimedes). But enough speculation - I'm neither a historian nor a scholar, just a kid with too much time on his hands. So, let's hear what someone else has to say.

The best (and only, to date) refutation of the event I've seen is by D.L. Simms, in the book 'Archimedes' weapons of war and Leonardo'. I have no idea about this guy's reputation, and I've never read the book... but going off of a second-hand source (Dr. John Leinhard at the University of Houston), here's what is said :

'Simms thinks the story hangs on the edge of plausibility. Archimedes might just barely have known enough optics to make such a mirror. It's conceivable that he could have made it with an adjustable focal length. He might even have been able to keep a beam fixed on one spot long enough to ignite wood. But beyond all those terrible if's was the fact that the burning mirror didn't appear in the earliest accounts of the battle. The first versions tell us only that Archimedes's ingenuity had something to do with winning the battle and that fire was involved.'

Well, there you have it. Like I said, decide for yourself whether or not to trust these sources... but it is something to think about.