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What was Archimedes' death ray?


Burning Mirrors: Could Archimedes' Death Ray Work?
The MIT researchers set the replica ship aflame using their own version of Archimedes' death ray.
The MIT researchers set the replica ship aflame using their own version of Archimedes' death ray.

Electromagnetic waves of light carry with them heat energy. This energy is reflected by shiny surfaces, such as smooth, polished metal or glass. The smoother and flatter a mirrored surface, the less the light wave is dispersed and the truer the reflected beam is to the original. With all of this in mind, and with the brief accounts of Archimedes' death ray available in the annals of history, some researchers have set out to determine if the death ray is fact or fiction.

Discovery Channel's "Mythbusters" gave it a shot twice in seasons one and three. Both times the experiments failed, and Archimedes' death ray received a "busted" decree. While the Mythbusters weren't able to replicate Archimedes' storied success, other researchers have. A group at the Massachusetts Institute of Technology (MIT) undertook a death ray experiment in 2005, and constructed a 10-foot (3 m) long, one-inch (2.5 cm) thick red oak version of a Roman ship. Using 127 one-foot (0.3 m) square flat mirrors arranged in a parabola (a concave arc), the researchers managed to set the model ship on fire.

After 10 minutes of reflected sunlight (without any cloud coverage interrupting the direct stream of light), the MIT team managed to cause flash ignition in the patch of the ship where the beams of sunlight were concentrated into a single area. This meant that the temperature of the area had reached 1100 degrees Fahrenheit (593 degrees Celsius). The ship caught flame and burned before the MIT researchers put it out. They had proven that Archimedes' death ray was possible. Or had they?

There are still some problems with the MIT experiment. First and foremost, the Roman ship under attack by MIT's version of the death ray was motionless -- the successful experiment took place on a rooftop. This means that the beam of reflected sunlight had time to do its work without interruption from the motion created by waves. This wouldn't have been the case for Archimedes, who would have the Mediterranean to contend with. Even a calm sea would produce slight motion in the boat, making it difficult to ignite a single area since the concentrated beam wouldn't rest in one area for very long.

This contention was dealt with in 1973, when a Greek engineer undertook his own experiment to get to the bottom of Archimedes' death ray. He assembled 70 soldiers, each holding a 5-feet by 3-feet (1.5-m by 0.9-m) mirror. The concentrated beam reflected by the mirrors set a row boat 160 feet (49 m) offshore aflame. It is possible, then, that Archimedes' death ray could have worked.

A great many people remain skeptical, however. Why hadn't any historians writing shortly after the siege of Syracuse mentioned the ingenious device when recounting the event? Perhaps the best argument against the historical reality of Archimedes' use of mirrors at the siege is that they weren't used again in later battles. Archimedes biographer Sherman K. Stein writes, "had the mirrors done their work, they would have become a standard weapon; yet there is no sign that they were added to the armaments of the time" [source: Stein].

Still, the legend persists. Thanks to continued interest among researchers who carry out their own experiments, Archimedes' death ray has been kept alive over the millennia. And even if the death ray's plausibility is definitively disproven in the future, it will have little dampening effect on the enduring genius left by Archimedes.


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