Archimedes: Separating Myth From Science

NY Times ^ | June 24, 2013 | KENNETH CHANG

[neverdem]

For the last time: Archimedes did not invent a death ray.

But more than 2,200 years after his death, his inventions are still driving technological innovations — so much so that experts from around the world gathered recently for a conference at New York University on his continuing influence.

The death ray legend has Archimedes using mirrors to concentrate sunlight to incinerate Roman ships attacking his home of Syracuse,...

--snip--

With his law of buoyancy, he was able to determine whether a paraboloid (a shape similar to the nose cone of a jetliner) would float upright or tip over, a principle of utmost importance to ship designers, and Archimedes probably realized that the Roman ships were vulnerable as they came close to the city walls.

“Archimedes knew about the stability of these kinds of ships,” said Harry G. Harris, an emeritus professor of structural engineering at Drexel who has built a model of the claw. “When it is moving fast through the water, it is stable. Standing still or going very slow, it is very easy to tip over.”

So using an Archimedean principle — the law of the lever, which enables a small force to lift a large weight, as in seesaws and pulleys — a claw at the end of a chain would be lowered and hooked into a Roman ship, then lifted to capsize the ship and crash it against the rocks.

Syracuse won the battle but was weakened under a long siege and fell three years later. And in 212 B.C., at the age of about 75, Archimedes was killed by a Roman soldier, supposedly furious that he refused to stop work on a mathematical drawing. His last words: “Do not disturb my circles!”

Of course, that bit about the circles is probably also a myth.

[ClearCase_guy]

Anyone who has seen what the Greeks and Romans had for “mirrors” would know that reflecting and focusing the sun’s rays into a long distance incendiary device was a ludicrous notion.

[JimSEA]

In high school some 55 years ago, the myth of the mirrors was taught as fact to illustrate the power of geometry.

[bigheadfred]

a ludicrous notion

Like my Aunt told me: The sun in Phoenix is different from the sun in Idaho. So the Greeks used a different sun is all.

[SunkenCiv]

GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach	join list or digest view topics view or post blog bookmark post a topic subscribe
Thanks neverdem. To all -- please ping me to other topics which are appropriate for the GGG list.

[Alex Murphy]

For the last time: Archimedes did not invent a death ray.

No, but the Atlanteans did.

[JCBreckenridge]

It could be done, actually. They used to coat their ships in pitch to keep them together.

[bert]

Difinitive Reference: Muthbusters Episode 46: Archimedes’ Death Ray

The theory was busted not once but twice by the engineers at Mythbusters.

Here's the video.

[norwaypinesavage]

"But in practice, the tiny difference in volume between a crown made of pure gold and one made of a mixture of gold and silver is too small to be reliably measured."

Leave it to the NYT to get even this wrong. The density of silver is 10.5 grams per cc while the density of gold is 19.3 grams per cc. There is nearly a 2 to one difference. It would be quite easy to determine the difference using Archimedes Principle. Simply weigh the amount of water displaced by immersing the crown in water to determine its volume. Then weigh the crown and divide by the volume. If it is anything less than 19.3 grams per cc, off with his head.

[Bigg Red]

Thanks for the ping.

[neverdem]

Thanks for the link.

[Sherman Logan]

Too complicated.

Just drop the weight of the crown in gold into a basin filled with water, which overflows. Pull out the gold via a string, and lower the crown in.

If any water overflows, the crown is not pure gold.

Archimedes didn’t have to figure out how much the gold in the crown had been diluted, only that it was.

[neverdem]

Atomic-Scale Structure of Ribosome Could Lead to Better Antibiotics

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Processed carbohydrates are addictive, brain study suggests

Psyllium helps fight type 2 diabetes mellitus I explained what is a statistically significant result in medicine in comment# 14.

Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women The A TO Z Weight Loss Study: A Randomized Trial Check the abstract.

FReepmail me if you want on or off my health and science ping list.

P.S. I just stumbled on the last link when I was trying to explain significant numbers. I added the diabetes list to this thread because they might not have seen that link on the other thread where they already got a ping.