Seeing as a lot of people still have no clue what the reference is:
http://en.wikipedia.org/wiki/Archimedes#The_Archimedes_Heat_Ray_.E2.80.93_myth_or_reality.3F
Archimedes lived from 287 BC to 212 BC, and was considered one of the leading scientists and inventors of antiquity, and an easy target of alien conspiracy theorists because of the revolutionary inventions he created.
During the Siege of Syracuse in 214-212 BC by the Roman Republic, it is said that Archimedes built several amazing devices to help the defenders of the city, including a "Heat Ray" or "Burning Glass" that could set enemy ships on fire from a long distance.
Historians have debated for a long time whether there's any credibility to this claim, and while Mythbusters considered this one 'busted' and impractical, this is an attempt to show that there is something 'off' with the whole thing. Lasers have only been around for a few decades, and have yet to even be put to use in actual military action, but somehow one was built over two millennia ago.