Archimedes' heat ray
A disputed ancient solar weapon attributed to Archimedes.
Wikipedia / Wikimedia Commons
Archimedes is said to have built a large solar furnace, often called a heat ray, to set fire to Roman ships attacking Syracuse around 213–212 BC. No mention of this device exists in Archimedes' own writings, and no contemporary records describe it, so most modern scholars consider it unlikely. By about 500 AD, the story was well known; the writer Anthemius of Tralles described a reconstruction. The 2nd-century author Lucian wrote that Archimedes destroyed enemy ships with fire, and Anthemius later specified that burning-glasses focused sunlight onto approaching vessels.
Debate over the heat ray's credibility has continued since the Renaissance. René Descartes dismissed it as false. Around 1747, the Comte de Buffon tested the idea and published a paper on burning mirrors. John Scott documented another experiment in 1867. In 1973, Greek scientist Ioannis Sakkas used 70 copper-coated mirrors, each about 1.5 by 1 meter, held by sailors at a naval base near Athens. Focused on a plywood mock-up of a Roman ship coated with tar paint at a distance of 50 meters, the ship burst into flames within seconds. Sakkas was convinced Archimedes could have used bronze mirrors to scuttle the Romans.
In 2004, the TV show *MythBusters* judged the mirrors implausible. The following year, MIT students tested 127 square mirror tiles, each 30 centimeters across, aimed at a wooden ship model 30 meters away. Under a cloudless sky, the ship sat still for about ten minutes before a patch caught fire. They concluded the device was feasible under those conditions. *MythBusters* repeated the test with a wooden fishing boat in San Francisco, producing some charring and a small flame, but the show ruled the claim "busted" due to the long time and perfect weather required. They noted that Syracuse faces east, so a Roman attack would need to happen in the morning for optimal sunlight, and that conventional weapons like flaming arrows or catapult bolts would have been far easier. In 2010, *MythBusters* conducted further tests, including one with 500 schoolchildren aiming mirrors at a mock-up Roman ship 120 meters away. The sail never reached the 210 °C needed to ignite, and the verdict remained "busted." The show suggested the mirrors' most likely effect would have been blinding or distracting the crew.
- purported inventor
- Archimedes
- period
- c. 213–212 BC
- location
- Syracuse
- field
- Weaponry / Optics
- known for
- Solar furnace / heat ray used against Roman ships
- status
- Disputed; no contemporary evidence
Lore & Background
The heat ray is not mentioned in the surviving works of Archimedes, and no contemporary evidence supports its use. It became an established story by around 500 AD, when Anthemius of Tralles described a reconstruction. The 2nd century AD author Lucian wrote that Archimedes destroyed enemy ships with fire, and Anthemius mentioned burning-glasses as Archimedes' weapon, focusing sunlight onto approaching ships to cause them to catch fire.
Modern attempts to recreate the heat ray have produced mixed results. In 1973, Greek scientist Ioannis Sakkas used 70 copper-coated mirrors at the Skaramagas naval base to set a plywood mock-up ship on fire within seconds. In 2005, MIT students used 127 mirror tiles to ignite a wooden ship after ten minutes under ideal conditions. However, the TV show MythBusters repeatedly tested the concept and concluded it was implausible, noting that conventional weapons like flaming arrows would have been far easier.
Reader's Guide
The Archimedes heat ray remains a subject of speculation and debate. Its significance lies in its enduring presence in historical lore and its role as a test case for the plausibility of ancient technology. Modern experiments have shown that concentrated sunlight can ignite a stationary target under ideal conditions, but the practical challenges—such as the need for cloudless skies, precise focusing, and a stationary target—make it unlikely as a reliable weapon. The story has inspired scientific inquiry and popular culture, including episodes of MythBusters and Richard Hammond's Engineering Connections. Ultimately, the heat ray's legacy is as a legendary example of Archimedes' ingenuity, even if its historical reality is doubted by scholars.
Did You Know?
- The heat ray does not appear in the surviving works of Archimedes and has no contemporary evidence.
- A 1973 test by Ioannis Sakkas used 70 mirrors to set a plywood mock-up ship on fire within seconds.
- MythBusters tested the heat ray multiple times and concluded it was implausible, suggesting blinding the crew was a more likely effect.
- The 2nd century AD author Lucian wrote that Archimedes destroyed enemy ships with fire.
Frequently Asked Questions
What is Archimedes' heat ray?
It is a legendary solar weapon supposedly built by the Greek mathematician to set Roman warships ablaze during the siege of Syracuse. The device is also called a solar furnace and is generally regarded as a disputed artifact of ancient warfare.
How did Archimedes' heat ray supposedly work?
Later writers describe large mirrors or burning-glasses concentrating sunlight onto the wooden hulls of approaching Roman vessels until they caught fire. No technical blueprint or description appears anywhere in Archimedes' own surviving works.
Is Archimedes' heat ray historically verified?
No. Neither Archimedes' writings nor any contemporary record from the siege period mentions such a device, so most modern historians and physicists treat the account as apocryphal or heavily embellished.
When and where did the heat ray incident supposedly take place?
The event is set around 213–212 BC at Syracuse, Sicily, during the Roman naval assault on the city. Archimedes is credited with deploying the weapon to protect the harbor from the attacking fleet.
How did the story of Archimedes' heat ray spread through history?
The earliest literary allusion comes from the 2nd-century author Lucian, who wrote of Archimedes burning enemy ships. By roughly 500 AD, Anthemius of Tralles had fleshed out a concrete reconstruction using burning-glasses, and the image stuck in popular imagination ever since.
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