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Examining the Antikythera Mechanism
Mr. Droopy Drawers writes "An ancient piece of clockwork shows the deep roots of modern technology. Found in 1900 off the coast of Antikythera, Greece, a clockwork mechanism was found to be a device for calculating the motion of the earth and planets. In an article in The Economist, Michael Wright, the curator of mechanical engineering at the Science Museum in London, says the device demonstrates mechanical principles that were thought not devised until the 17th century. The article quotes research done by Derek Price. Here's Mr. Price's article from Scientific American. Also found some quicktime movies of the mechanism at The University of Macedonia. Very interesting reading."
...is greek and doesn't belong to the country-with-similar-name, namely FYROM (former yugoslav republic of...).
It seems I messed up the link in my previous post.
The second article is here instead. Oops.
Economics is the key. When you are limited by the amount of money you have, you can't do any research. And yet money is just a piece of paper now, and yet it'll still lead us to the next depression. Looks like we still haven't learned anything this past 2000 years. (Most Greek scientists are either rich themselves or are supported by the rich...)
The problem the Greeks would've had was "why don't they 'fall' just like objects on the Earth do?" The answer they came up with was that the bodies in the sky were "ethereal" (essentially massless in modern parlance) and were moved about in regularity by the gods (or the planets' Ideals if one were a Platonist). Thus they wouldn't have imagined the bodies in space to be like the matter on Earth, making, by default, the Earth the center of the cosmos.
Religion is the opiate of the masses. The wealthy smoke the real stuff.
Actually, Aristarchus, a Greek aroud the early part of the 3rd century BC, came up with it. Copernicus basically rehashed what Aristarchus said, improved on it a bit, and now most people believe that Copernicus came up with the idea.
Well, even the heliocentric model presented by Copernicus contained epicycles. Not quite as many as the Ptolemaic system (which was a mathematical mess by the 16th century as the general model was continually appended rather than torn down and rebuilt), but there were still definitely some. Copernicus created a heliocentric universe that had circular orbits for all of the bodies. Coming from the knowledge that planetary orbits are elliptical, we can see how this leads to problems. For example, if the position of Mars is charted nightly against the background of the stars, there will be instances where it appears to move one direction for a few nights, then stop, turn around, start moving backwards for awhile, then stop, turn around, and then proceed on its usual course!
The way to explain this sort of oddity and yet preserve your blessed circular orbits is to insert epicycles. The planets are traveling in circles while orbiting a central body (the sun, or the earth). With some tinkering, an epicyclic system can be constructed that fits fairly well with observations taken from the vantage point of earth, at least most of the time. Not all the time, mind you, which is why it too had some (in hindsight, again) rather pathetic attempts to patch it up, epicycles on the epicycles and rot like that. Heliocentric theories had been proposed before, as another poster mentioned, by Aristarchus in ancient times, and then Nicholas de Cusa in the 15th century. Both of these models suffered from the same type of complexity that the one put forth in De Revolutionibus Orbium Coelestium.
What made Copernicus different is that he worked out a real mathematical basis for his solar system. Copernicus also correctly realized that the system could be made simpler if the inner planets moved faster than the outer planets, and thus completed their orbits even faster than distance of the circle they covered alone would predict. This seems obvious now- inner orbits must move faster, because gravitational forces varies with the inverse square of distance, but Copernicus lived before Newton, so he wasn't operating with that knowledge. His system was incorrect, yes, but it was at least based on something more concrete than aesthetic value. It then fell to Kepler to divine the true mechanics of the Solar System. His calculations showed that if the orbits of the planets were ellipses, with the Sun at one focus (he introduced the word "focus" in this context, btw), then the whole epicycle thing wouldn't be necessary at all to fit experimental observations. Moving on ellipses meant that the planets did not move with constant velocity- they moved faster when closer to the sun, and slower when farther away. Combined with Copernicus's concept of the inner planets moving faster, bolstered with mathematical properties of ellipses to become Kepler's Third Law, the whole epicycle thing became pretty much unnecessary.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."