13-year-old wins science fair for attempting to demonstrate Archimedes' fabled "Death Ray"

[Endymio]

Why do you hold onto the ideal conditions nonsense that a ship in the water is going to be perfectly still during a perfectly clear & sunny day while the crew waits around for you to slowly burn their ship?

I think you've seen Pirates of the Caribbean a few too many times. Ancient sailing ships didn't come and go as they please: they were "at the mercy of wind and tide". Ships nearing a harbor nearly always had to wait for proper tide conditions to enter, and history records cases of ships sometimes having to wait several weeks -- weeks -- just outside a harbor, due to unfavorable wind conditions. Unlike what you see in a Hollywood film, you can't just spin the steering wheel and go.

Furthermore -- and this is the ironic part -- you fail to realize that during the Siege of Syracuse (in which this event purportedly occurred) those ships laid siege to the port for many months, waiting just offshore "motionless, on clear and sunny days".

You mean those videos where they have to put targets a few inches away from the parabolic mirror?

The thing about concentrating more light in a parabolic dish and in other types of curves with steeper angles is that they focus the light at a closer and closer point...

I was wondering when you'd get to this, as this was the primary error Mythbusters made. The term you're searching for is "effective aperture". If you wish a high gain focus on a target 200 meters away, you need a parabola on the order of 200 meters across. Since this isn't practical, you use the same principle that radio telescope arrays use -- a number of much smaller reflectors, arranged to combine their effect. But a modern radio array can electronically combine its signals regardless of the spatial arrangement of its elements. Doing something similar in ancient times would require the elements themselves to be arranged along a lengthy parabolic arc.

Archimedes, it seems, was indeed a little more intelligent than the guys at Mythbusters.

 

[Bluescreendeath]

I think you've seen Pirates of the Caribbean a few too many times. Ancient sailing ships didn't come and go as they please: they were "at the mercy of wind and tide". Ships nearing a harbor nearly always had to wait for proper tide conditions to enter, and history records cases of ships sometimes having to wait several weeks -- weeks -- just outside a harbor, due to unfavorable wind conditions. Unlike what you see in a Hollywood film, you can't just spin the steering wheel and go.

Furthermore -- and this is the ironic part -- you fail to realize that during the Siege of Syracuse (in which this event purportedly occurred) those ships laid siege to the port for many months, waiting just offshore "motionless, on clear and sunny days".

Have you seen how ships behave on the water (especially while you are on the ship)? Ships will gently sway with even light wind and waves. People today can still get motion sickness/sea sickness even when on modern giant cruise ships that are dozens of times bigger & heavier than and are far more stable (far less swaying) than Roman warships.

Light winds and waves during a clear and mostly calm day is not going to prevent a ship from being able to enter a port. You're confusing the difference between bad weather (eg. heavy winds and heavy waves) that toss around a ship VS good but not completely perfect weather (clear day with some light winds/waves) that makes a ship lightly sway.

What you're missing about the siege of Syracuse was that those ships were NOT waiting in the same spot while motionless/not moving for months. The siege was a land siege and a naval siege + blockade - the ships were ferrying supplies to the soldiers and moving back and forth. Just because a siege lasted for months doesn't mean the ships just waited there doing nothing.

And waiting offshore means they were well out of range from the city's defenses (and bows & arrows, ballista, catapults, etc would all outrange the hypothetical death ray). Those ships were not sailing right up to the city (within the short range of the mirror beams) and staying absolutely motionless while doing nothing.

I was wondering when you'd get to this, as this was the primary error Mythbusters made. The term you're searching for is "effective aperture". If you wish a high gain focus on a target 200 meters away, you need a parabola on the order of 200 meters across. Since this isn't practical, you use the same principle that radio telescope arrays use -- a number of much smaller reflectors, arranged to combine their effect. But a modern radio array can electronically combine its signals regardless of the spatial arrangement of its elements.

You've already forgotten we've discussed this problem before. We already discussed the pros and cons of a single giant device vs multiple devices above.

Having multiple parabolic dishes runs into the same problem of having multiple other types of reflectors - it becomes difficult to coordinate multiple devices with a focal point of a few inches on a target hundreds of feet away (it is already difficult for stationary targets, and will be near impossible for moving targets). A deviation of a few centimeters or inches at the mirror will throw off the final beam focal point by several feet...so you end up with a dozen beams pointing at different spots and dispersing their energy.

And modern day radio telescopes are arrayed and controlled by electronics & computers to point towards a location in the sky to recieve radiation from space. They then piece together the bits of data they recieve. So it is not exactly the same as the telescopes all reflecting radiation towards a single point (and they would need pinpoint precision run by electronics & computers to do that).

The Mythbusters made 1 large parabolic-shaped device in one test, and used multiple smaller no-parabolic devices in an earlier test. Using multiple smaller parabolic devices runs into the same problem as the earlier test where it was hard to coordinate multiple devices.

Doing something similar in ancient times would require the elements themselves to be arranged along a lengthy parabolic arc. Archimedes, it seems, was indeed a little more intelligent than the guys at Mythbusters.

Except no historical source, primary or otherwise, ever claimed Archimedes did this. Not even the later sources that invented the myth centuries after Archimedes death claims he created and combined multiple parabolic devices to set fire to ships. This is all based on modern speculation on how he could have achieved this if he did actually do so based on the anarchonistic myth.

And we again go back to the fact that none of the original sources or primary sources claims Archimedes ever created a death ray/sun light ray/etc to set Roman ships on fire.

So this is all just speculation about something based on an anachronistic myth that isn't even backed up by history.

 

[Endymio]

Light winds and waves during a clear and mostly calm day is not going to prevent a ship from being able to enter a port

Err, yes it will. When you have no wind -- or a wind blowing directly away from that port - what magic force do you think will propel you forward? Even when the wind isn't perfectly foul, if the tide is ebbing, that port is an inaccessible as the dark side of the moon.

You're confused about the massive size of some of these ships -- quadriremes and quinqueremes carried complements of hundreds of men across 5 and 6 decks, and at least one flagship of antiquity carried a crew of 2,800. Ships this size do not bob about on the waves like a toy boat. Myself, I've taken been on lengthy cruises on ships ranging from 20 passengers to 3,000+. Even on smaller boats, there is little to no motion on calm days -- unless you're docked, where the action of the waves is vastly accentuated by the proximity to land.

What you're missing about the siege of Syracuse was that those ships were NOT waiting in the same spot while motionless/not moving for months. ... the ships were ferrying supplies to the soldiers and moving back and forth.

Which part of "naval blockade of a port" do you fail to understand? And warships full of marines do not "ferry supplies" -- Marcellus had grain transport ships especially for this purpose.

And waiting offshore means they were well out of range from the city's defenses (and bows & arrows, ballista, catapults, etc would all outrange the hypothetical death ray).

The sun's rays travel 93 million miles to reach the earth. Assuming Archimedes had enough wall space to work with, he could have easily devised a focal range of 400 to 500m -- significantly beyond that any bow or onager from the period.

Having multiple parabolic dishes runs into the same problem of having multiple other types of reflectors - it becomes difficult to coordinate multiple devices with a focal point of a few inches

Why do you keep repeating this "parabolic dish" bit? If Archimedes used a faceted array, the individual elements themselves have been flat. Assume each of these is a 1.5 m square reflector, then your "focal spot" is more than 2 square meters in size. And -- if you point 70 of them at the same spot on a ship, you're focusing 100,000+ watts on that spot ... enough to *instantly* ignite the standing rigging of any ship built, to *instantly* blind a helmsman, and, with a second or two's exposure, ignite solid wood.

Except no historical source, primary or otherwise, ever claimed Archimedes did this.

Yes, yes - the first references to Archimedes using "burning glasses" (which to me suggests lenses more than mirrors) to ignite ships came in the 2nd century AD. But we're not arguing whether or not Archimedes actually did this. We're arguing the feasibility of the approach.

Personally -- and for the record -- I've never thought Archimedes actually set ships of fire. The alternate explanation that he used a similar device to flash-blind a helmsman or other crew is certainly more plausible.

 

[Bluescreendeath]

Err, yes it will. When you have no wind -- or a wind blowing directly away from that port - what magic force do you think will propel you forward? Even when the wind isn't perfectly foul, if the tide is ebbing, that port is an inaccessible as the dark side of the moon.

Light wind will not stop a ship. These ancient ships had a huge crew of rowers because they were oar powered. Many if not most of the crew in these ancient Mediterranean ships were for rowing the oars - far more than for manning the few sails they had.

You're confused about the massive size of some of these ships -- quadriremes and quinqueremes carried complements of hundreds of men across 5 and 6 decks, and at least one flagship of antiquity carried a crew of 2,800. Ships this size do not bob about on the waves like a toy boat. Myself, I've taken been on lengthy cruises on ships ranging from 20 passengers to 3,000+. Even on smaller boats, there is little to no motion on calm days -- unless you're docked, where the action of the waves is vastly accentuated by the proximity to land.

There is a big difference between extremely large luxury floating barges VS the much smaller more typical ships that were actually seaworthy and used in combat.

The largest ancient ships with 1000+ crew were usually floating barges used on calm lakes that were incapable of being used at sea.

The average Roman ship used in combat at sea only had a few hundred crew. See the Battle of Cape Economus for example. The Romans had about 300-350 ships and 140,000 sailors & crew. That comes out to an average of 400-470 people per ship. A ship like the Greco-Roman quinquereme usually carried about 400 people, displaced 100 tons, and was typically around 150 feet in length. A typical modern cruise ship holds 3,000+ people, displaces 70,000 tons, and is around 1,000+ feet in length.

So a modern cruise ship is far larger than a typical ancient warship. And even a cruise ship that is much more stable at sea still sways enough to cause sea sickness for some passengers. And a ship doesn't need to bob up and down like a toy boat. When the focal point of the mirror beams is only a few inches across, the ship even going up and down by a few inches will throw off the target area of the beams.

Which part of "naval blockade of a port" do you fail to understand? And warships full of marines do not "ferry supplies" -- Marcellus had grain transport ships especially for this purpose.

What part of ships don't wait around perfectly still doing nothing while being attacked do you not understand? Why would naval ships in a blockade that is doing nothing and laying motionless go right up against the walls within the defender's weapons range and let themselves be torched?

If they are waiting around, they're not going to be within striking distance. If they are within striking distance, then they are moving.

The sun's rays travel 93 million miles to reach the earth. Assuming Archimedes had enough wall space to work with, he could have easily devised a focal range of 400 to 500m -- significantly beyond that any bow or onager from the period.

The Mythbusters array was 300x pieces of 1 foot wide mirror tiles arranged into a device that was 110 feet long and had a range of ~150 feet (or 45 meters) and that still took several minutes to slowly light a motionless ship on fire.

By enough wall space to get a range of 400-500 meters (which is ~1600 feet), you mean if he somehow acquired thousands of reflectors that collectively are thousands upon thousands of feet across. So obtaining enough reflecting devices that would cost enough to bankrupt a small country or be able to raise an entire army.

And to coordinate and aim these reflectors, they're moved around by something that can all move thousands of these reflectors at the same time and aim with pinpoint precision. Since it is already difficult to get regular humans to even coordinate aiming dozens of mirrors at a target a mere 100-200 feet away, you'll need those thousands of reflectors controlled by either machinery with computers or thousands of superhumans trained from birth to excel in specific mental tasks (like the ones in Dune) to coordinate and aim at something over a thousand feet away.

If we want to start getting into far fetched hypotheticals, then we might as well say Archimedes had lasers given to him by alien extraterrestrials and was shooting at the Romans with extraterrestrial lasers that caused their ships to burn.

Why do you keep repeating this "parabolic dish" bit? If Archimedes used a faceted array, the individual elements themselves have been flat. Assume each of these is a 1.5 m square reflector, then your "focal spot" is more than 2 square meters in size. And -- if you point 70 of them at the same spot on a ship, you're focusing 100,000+ watts on that spot ... enough to *instantly* ignite the standing rigging of any ship built, to *instantly* blind a helmsman, and, with a second or two's exposure, ignite solid wood.

You're the one who brought up a parabolic arcs and youtube examples of parabolic dishes in the first place and used parabolic dishes as an example of something small being able to intensely focus sunlight. I pointed out parabolic dishes can more intensely concentrate the sun's light but have far less range. If you go in the other direction, you get more range but less power.

And why do you keep ignoring the flaws we've already talked about and the fact that we've gone through this same conversation over and over again? We already stated multiple times above that it is extremely hard to coordinate multiple reflectors to all aim at the same spot.

How are you going to aim 70 extremely large and extremely unwieldy reflectors that are 1.5m/5 foot across (each as big as a person) when even smaller devices are already unwieldy and difficult to aim at a completely motionless target?

Yes, yes - the first references to Archimedes using "burning glasses" (which to me suggests lenses more than mirrors) to ignite ships came in the 2nd century AD. But we're not arguing whether or not Archimedes actually did this. We're arguing the feasibility of the approach.

We're arguing whether the myth makes sense, whether it is even remotely practical, and whether it happened. If you want to discuss general feasibility, that includes taking into account the money, manpower, resources, etc spent building a device vs alternative options.

That is unless you are talking about hypothetical feasiblity as in if it is "technologically or technically possible" if some crazy person with vast resources could do this with their technology at the time.

It is hypothetically technologically/technically feasible, but it is not generally/practically feasible to torch a ship with sunlight. Someone has to decide to waste their nation's resources building expensive reflecting devices that then needs to be set up & controlled by hundreds or more humans so they can slowly burn motionless enemy ships one at a time at close range in an event that can only happen on a clear, sunny sky.

It is also hypothetically technologically/technically feasible to win a battle with nothing but snakes and bees if a king decided to do nothing but send his army to gather all the snakes and bees across the land, put them in jars, and have his army use no other weapons except flinging snakes and bees in pots at enemies and the enemies are very allergic to bee stings and are afraid of snakes.

Personally -- and for the record -- I've never thought Archimedes actually set ships of fire. The alternate explanation that he used a similar device to flash-blind a helmsman or other crew is certainly more plausible.

Yes. Agreed.

 

[Endymio]

Despite the wall of words, you've still failed to address the biggest problem. Mythbusters-- and similar tests -- all attempted to set fire to thick solid wood timbers. Whereas the history of naval warfare, from the time of the ancient Greeks to the Napoleonic Wars, shows that the vast majority of ships damaged or destroyed by fire began with the far-more-flammable canvas sails or hempen-rope standing rigging catching fire, or sometimes a freshly pitch-covered surface. These ignite and burn in a flash, and set more of the ship on fire.

Furthermore, Mythbusters, didn't even use a parabolic reflector, nor was their dish anywhere near as reflective as the Roman's silver- or tin-plated methods would have achieved.

Finally, the fact remains that some tests have indeed been successful:

"....in 1973 ...70 mirrors were held up by Greek sailors, each with a copper coating and a size of around five by three feet (1.5 by 1 m). The mirrors were pointed at a plywood mock-up of a Roman warship at a distance of around 160 feet (50 m). When the mirrors were focused accurately, the ship burst into flames within a few seconds...."

Light wind will not stop a ship. These ancient ships had a huge crew of rowers...

No, but an ebbing tide will. While tidal currents rarely exceed 3-4 mph in the open Med, they are amplified in harbors, sometimes as high as 10-15 mph -- far faster than a trireme can row.

There is a big difference between extremely large luxury floating barges VS the much smaller more typical ships that were actually seaworthy and used in combat.

The ship I mentioned was actually used in naval combat of the era -- and all the ships used in the Siege of Syracuse were triremes or larger. Ships carrying several hundred men do not bob about on the water like rowboats. In calm weather, as seen from the shore, you can't even see ANY motion whatsoever, much less enough to disrupt someone's aim.

By enough wall space to get a range of 400-500 meters (which is ~1600 feet), you mean if he somehow acquired thousands of reflectors that collectively are thousands upon thousands of feet across.

LOL, what? Have you never seen a radiotelescope array? The EHT array has an effective aperture the size of the planet earth ... and it does so with just a few dozen telescopes. You don't cover the entire area along... the array is sparse, with most of it empty space.

 

[captaincranky]

Look how far this technology has come..! Nowadays, you can even light cigarettes with it..