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Archimedes Death Ray
Werner Heuser writes "Ancient Greek and Roman historians recorded that during the siege of Syracuse in 212 BC, Archimedes (a notably smart person) constructed a burning glass to set the Roman warships, anchored within bow and arrow range, afire. The story has been much debated and oft dismissed as myth ... Intrigued by the idea and an intuitive belief that it could work, MIT's 2.009ers decided to apply the early product development 'sketch or soft modeling' process to the problem."
For the unitiated, 2.009 at MIT is a class in course 2 (mechanical engineering), called Product Engineering Processes.
... and the server is a smoking husk before the first comment is posted.
Help poke pirates in the eyepatch, arr.
The server seems really slow right now, try this.
And Mythbusters is LAW!
The Tech Terminal
Not to argue that the mythbusters are always right, but they've disproved this in one of thier episodes. They did some pretty good convincing after building a trireme and using a few hundred mirrors and only reaching a couple of hundred degrees (F).
h busters.html
Mythbusters: http://dsc.discovery.com/fansites/mythbusters/myt
IT BURRRRRNS! The same Archimedes whose last words were "Do not disturb my circles!" at Syracuse. The Wikipedia article links to the same story at MIT. http://en.wikipedia.org/wiki/Archimedes Quite the inventor!
That's an Archimedes Death Ray, now banned from all commercial airline flights. Lame.
This sort of demonstration has been done before. I remember reading an article in Time magazine in the 1960's or 70's that reported on one such earlier experiment. Many men held polished flat "shields" in the sun at the right angle, and confirmed that they could cause charring in a simulated boat target.
I personally thought that they didn't do a very good job at testing it and they could have definitely gotten it to work if they did a better job setting up the mirrors. (of course they like to claim they "busted" something even when it was inconclusive or mostly true)
Flash ignition!
In an instant there is a large, open flame. The volatiles liberated from the wood ignite at roughly 1100 F.
Open, sustaining flame occurred less than 10 minutes after the sun was in a clear patch of sky!
You can also clearly see that there are still 3 mirrors not aimed correctly.
Now that Mythbusters is wrong, are there other myths that could be true?
if the ships were within arrow range... wouldn't a flaming arrow have done the job just as well... why the over engineering?
Not exactly the same concept, but the Solar Death Ray always reminded me of this.
How's my typing? Call 1-800-eta-shut
No wonder why the webpage says:
8 15d479865f65c52/index.html
"Click on image thumbnails to see a larger images. Video clips will be online next week"...
Why next week?
Can't we just take down the entire MIT web server! =P
So, those poor students in mid-session won't be able
to access to their course material and similar! =)
That's nice a new excuse just came out!
"Sir, I couldn't do my assignment, because the MIT web server was slashdotted,
so I couldn't access the course material, can I get an extension.... PLEASE!!!!"
So, next time, you guys have a hard deadline assignment,
please just post an article on slashdot and there you go.
For everyone else, please use the Mirror...
http://www.mirrordot.org/stories/90e7777b89ad9e53
For what it's worth, the MIT folks said they couldn't unequivocally rule it out. They didn't say it happened. One of the main points on Mythbusters was that it seemed like it might work, but the fleet would have had to remain essentially motionless for the wood to get hot enough for ignition. The MIT folks did nothing to answer that as they the mirrors and the "ship" were motionless until ignition.
If Nalgene water bottles are outlawed, only outlaws will have Nalgene water bottles.
as tin foil hadn't been invented yet, his enemies would have had no viable defense against this weapon. Devastating!
Solar Death Ray
Looks like the renewable energy people are in on it, too
I also remember seeing one in my chemistry book last year... it was in france or somewhere (theoretically temperatures could get high enough to ignite something with a low flashpoint like wood or paper). The mythbusters' argument was that copper wasn't shiny enough and that even with mirrors, the soldiers wouldn't have enough precision to focus on a point for long enough.
-TX297
in 212 BC, Archimedes (a notably smart person) constructed a burning glass to set the Roman warships, anchored within bow and arrow range, afire.
If the enemy ships were anchored within bow and arrow range, I suspect that while Archimedes was fiddling with his mirrors, a few archers dipped their arrows in pitch and fired them at the fleet. Eventually, when Archimedes finished aiming his master weapon he was overjoyed to discover the fleet in flames. Archimedes reported his success to the king, and went down in history as the oldest recorded example of a horribly over-engineered solution to a simple problem.
Igniting sails, or burning/blinding people is much easier than setting fire to wood (especially a hull that could be wet). I've always thought that the victory was due to the psychological effects of the weapon on morale more than the outright destruction of vessels.
Yes, Archimedes was a very smart cookie, but he was surrounded by other smart cookies, who were also geting up to interesting things. IMO, ancient Greece was pretty much as technologicly advanced as 15th century Europe. Why we ended up having the industrial revolution, and the Greeks did not, becomes a very interesting question.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
A mirror can also prevent the server from burning up.
Marvin knew: "Think of a number, any number..."
I remember a Mythbuster episode where Adam & Jamie try to reproduce this myth/story. They were not able to set a boat hull on fire (they built a replica-piece of boat hull from that age). Stronger still they barely managed to get the temperature higher up... iirc it was only a few degrees higher in the focused center of the beam.
The best weapon of a dictatorship is secrecy, but the best weapon of a democracy should be the weapon of openness.
They run these unscientific experiments (most involving explosions or decaying corpses) and then "conclusively bust" myths. Some experiments are fun and interesting, but most don't deserve the hard conclusions they assign.
It's really annoying when people take accept their "proofs" as proofs.
"So what's that in units that the rest of the world uses?"
You can express it as 1 getacalculator (or 10^youlazyfuck if you prefer scientific notation).
Yep, but as ohters have said, the greeks used slave labour for their construction/manufacturing and therefore had little incitement to invent other things than warmachines (greek fire, imagine a giant roman candle) and toys (as in this example with 'agitated air' as he called it as far as i remember).
Yours Yazeran
Plan: To go to Mars one day with a hammer.
The other answer to my post from the AC above probably nailed it. "Why build a factory when you can have slaves do it?" The class of Greeks that had the time to dabble with steam engines had no incentive to build labour saving devices.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
Not really all that interesting of a story in my opinion.
Mathematics is made of 50 percent formulas, 50 percent proofs, and 50 percent imagination.
It's in Spanish, but it does have a photograph of about 40 of the 70 man-sized mirrors they used. He managed to ignite a tarred wooden boat in about 3 minutes.
I am now seeing "Forbidden" when trying to access the original MIT web page, however Google claims there is mention of the Sakkis experiment on this one (also forbidden).
This is before bow 'n' arrows, back in a time when lasers were the weapon of choice.
I remember when legal used to mean lawful, now it means some kind of loophole. - Leo Kessler
Since the Greeks had gears and ropes, it would have been possible to build a mechanism whereby one person could rotate many mirrors. I'm not saying it would have been easy, or even that it was done this way, only that they had all of the required technology to do it.
A second possibility would have been similar to the sighting mechanism used very successfully by the Dambusters in their attacks in World War II on German dams. They needed to know when they were at a certain height above the water, level, and at a certain distance from the dams. They achieved this by angling the searchlights to cross over at the right height and strike the dam at the right distance. To know if they were level, they used pieces of wood at different distances, which would line up when the aircraft was level.
To line the mirrors up with the ship, you'd need to know when the light from the sun would strike the ship at the right height. Angle of incidence equals angle of reflection, so as the sun moves through the sky, you'd need to shift the mirrors both horizontally and vertically to keep the light on the right spot.
If you had a hole in the mirror and stood behind it, you could swivel the mirror to face the ship. Since the ship would be at water level and the mirror would probably have been much higher, the mirror would have to have pointed at the tallest mast. It would be the only thing visible. To ensure all mirrors pointed the right way, each mirror would need behind it a stick that needed to line up with the mast, but set at an angle such that each mirror would line up differently along a crude parabolic curve. Shouldn't have been hard, with the Greek knowledge of geometry, which they were exceptionally good at.
If the action was brief enough and at the right time of day and at a predictable distance, the vertical angle would be unimportant. If it had to be ready for ANY time of day OR at ANY distance, then you'd need to have the poles on which the mirrors were attached themselves movable.
If you mounted the pole on one end of a see-saw, then added weights to the other end, you would be able to adjust the vertical angle of the mirror to whatever was required. The line of the see-saw would be parallel to the normal of the mirror. You can tilt the mirror such that the reflected light will intersect the ship at the same point that the line along the see-saw intersects the ship. This would guarantee all mirrors get identical vertical alignment.
We now have a guaranteed way of aligning a great many mirrors onto an identical point on a ship at any distance at any time of day, using nothing more than geometry, alignments and pivots. Again, this is NOT to say that this is how it was done - we don't know HOW it was done, or even IF it was done. What this is saying is that the arguments against have largely been based on sophistication, but that the required level of sophistication was certainly achievable had anyone wanted to achieve it.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Read your link. Greek fire was invented in 673 AD.
Something like only needs to be used once to be effective. After that, the mere idea that it exists is a deterrent. Two other examples of this working:
1) The ancient Israelites carried a large gilded box called the Ark of the Covenant in front of them into battle. They believed it could summon up the wrath of God on their enemies. Their enemies were not 100% sure that the Israelites weren't right. There is no evidence that the Ark ever actually did summon up the wrath of God, but boths sides beleived it and the Israelites beat enemies who had superior numbers on a number of occasions.
2) How many atomic bombs were actually ever used? Two. But the mere thought that a country has nuclear weapons gives them a bargaining position. And the the fact that the wrong country even MIGHT be trying to obtain them is reason to go to war.
In the ancient world, this "death ray" would have struck fear in the enemies hearts and minds, despite the fact that it might have serious limitations, or may not even work at all except in controlled situations. And one or two prominant demonstrations of such a weapon would go a long way toward keeping this fear going.
Don't forget Archimedes acquired a reputation in his lifetime that has lasted more than two thousand years. That is, he was not only considered the smartest man in his generation, but one of the smartest men ever to live for another hundred lifetimes of men, all over the Western world. He was very probably the ancient world's equivalent of Newton, Einstein and Fermi all rolled into one.
Further, given that he was at the time of his supposed feat a powerful figure in Syracuse, and the fact that the fate of a conquered ancient city was dire -- the city leaders would be paraded and killed, and everyone else sold into slavery -- Archimedes probably had access to all the material wealth of the city, and as much willing -- nay eager -- manpower as he could wish.
Given those facts I would hesitate to scoff at the myth on the basis of what can be achieved, or not, by a mere dozen modern men, of average intelligence* and creativity, working with trivial amounts of money, and not nearly as motivated as men facing enslavement, an ugly death, or in many cases both.
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* Yes, I know the MIT students are no doubt above average in intelligence. But the odds that their number includes someone so clever and inventive that his name and accomplishments will still be common knowledge twenty centuries from now seems remote, to say the least.
Andam Hart Davis has a programme on the BBC at the moment and in it he created the experiment at a smaller scale. He used a round disc with a lot of small flat mirrors that could be tilted to focus a beam of light onto a boat. With in a few seconds smoke started coming out. It worked and was shown on tv recently.
So i got to read it...
Looks like they calculated how much energy it would take, then upped that by a bit, then carefully aimed their mirrors to achieve the required flux. It worked. If they were able to get smoke from 129 self-aimed, 1ft. mirrors, get a few thousand soldiers on a hill, and see what they can do.
btw... the math on the power of the mirrors is wrong. if the mirrors are flat (and you can think of a curved mirror as many small flat ones), then the mirrors effectively apear to be another sun. from the targets point of view a mirror(or part of one) is either reflecting the sun or not. The total flux at any point comes from how big (angular) the total surface of all the reflecting mirrors apears to the target. That's why a small, close, shaped reflector (or lens) can burn things, and why it's harder to scale up.
-John Fenley
For one, they do *many* more experiments than they show on air. Check out their website for details - basically, for every one experiment that makes it to air, they did 5. In reference to this episode in particular, you can be sure they tried many different cell models with many different levels of gas. These guys have quite a large budget to work with, they aren't going to skimp out on one cell phone.
For two, in reference to this particular episode, they did bust the myth that a cell phone can cause an explosion *through normal useage*. What they ended up saying, is in all likelihood the reported explosions were not coming from cell phones, but were a result of static electricity buildup at the scene. This is entirely plauseable. In my last car, depnding on the clothes I was wearing, I would often get actual blue sparks coming from my fingers to the door handle if I touched the car in the wrong way while getting out of it.
An explosion from a spark caused by static is much more likely than anything caused by a cell phone. How could useing a cell phone or having it ring *possibly* be any ore dangerous than a car radio? The car radio operates simmilar electronics, and hell, old ones even have rotary contact-based resistors for the volumne, which would be an ample source of spark potential. Any cell phone whose batter is sparking is not going to work properly because the battery is not making proper contact with the battery, so your calls would be constantly dropping. No one would use it.
I can only assume you were misinformed or made the wrong assumption about the show. Perhaps you are missing out on what Mythbusters is about. It's this funny little thing called "entertainment".
It is not an "Educational" program. It's about 2 guys who used to do FX work for Hollywood using their skills with "getting close" to the right thing trying to see if they can replicate urban legends.
The funny thing is, you probably missed the episodes where they revisit old myths they worked on. If the show receives enough requests from the audience or they decide they didn't do something justice, they give it another go. They did the "chicken gun" myth a couple times because they kept doubting their setup. I didn't get to catch the final conclusion, but I would say that by the time they were done, they had tried everything available to them to see what would happen.
Other examples of where they've done things incredibly right include hanging a pig carcass from a hook on a pivot and shooting it with various guns to prove that no, taking a gunshot does not make you fly back and do cartwheels, and using a ballistics gel dummy (with a pig backbone to simulate the human one) to determine if you could be injured by a ceiling fan (even the high-powered ones didn't do much until they sharpened the blades).
Yes, most people who have shot guns would understand that Hollywood fakes it, but for the average Joe who just watches movies and TV, with no physics background, it was probably something neat to see.
Yes, they blow stuff up. They put a crash test dummy through hell. Yes, they keep fuck-ups on the film, because that makes the show more approachable to the target audience- it isn't a dry, we-just-provide-the-facts-ma'am-only-the-facts show. It is supposed to feel like you and you buddies could be right there with them. You know what, though? It's entertaining. And for a channel that brings us 5 variations on "hey, we're going to destroy a room in your house by letting a half-assed decorator come in and ruin your happiness", it's a damn good show.
Many of their conclusions are valid. They've shown that pissing on the "live" rail of a 3-rail train system will not shock you (urine stream is too fragmented by the time it hits the rail for electricity to travel), exactly how many bug bombs you would have to set off in a room with an ignition source before the gas was concentrated enough to explode, and that you cannot get sucked into the intake on one of those firefighting helicopters while wearing scuba gear, only to be dumped into the fire and die.
The parabolic reflector gaves at the focal point a maximum flux of 1000 W/cm2. The experimentations takes place at the focal zone (18 m in front of the paraboloid. The range of available temperature is from 800 to 2500 C (the maximum reachable temperature is 3800 C) for a maximum thermal power of 1000 kW.
http://www.imp.cnrs.fr/foursol/1000_en.shtml
I respect the fact that MIT has its own unique course numbering system, and curricula are referred to by numbers rather than by name. However, it does bug me that MIT folks expect their bizarre internal numbering to make sense to outsiders. If one didn't know better, one might even see it as some sort of bizarre exclusionary "in group" code. But I suspect that it's just cluelessness, combined with intense isolation.
There is a technique for aiming the mirrors easily and quickly, provided that one person holds each mirror and the mirrors are reflective on both sides. Make a hole in the center of the mirror. Open only one eye. Position the mirror so that you see the target in the hole and the sun shines through the hole onto your face. Tilt the mirror so that the image of the spot of sun on your face is centered on the hole.
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