Ancient Greece - Movements of Heavenly Bodies.

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Most likely all of you are familiar with the theory, as formulated by Johannes Kepler, that the heavenly bodies rotate around a center (the sun) and that earth (in contrary to prior beliefs) is not that center.

In ancient greece there was quite a bit of speculation on just how these heavenly bodies moved through the sky, as all of you may know. That was the reason that the information which I will outline below surprised me quite a bit.

In the fourth century bc a Greek philosopher named Eudoxus described the orbit of all of the heavenly bodies (the sun, moon and planets) as the result of combined rotations of multiple concentric spheres. These spheres were all in orbit around Earth. The spheres are depicted here as objects with a rotation of it's own, and as moving along with the other spheres. There were several layers of these spheres, and the outermost was the one in which planets existed.

Later Aristotle took Eudoxus' system (or actually a version slighty modified by a pupil of his: Calippus) and formed it into a physical model. The concentric spheres were now regarded as factually existing spheres, of which the outermost (the one holding the unmoving stars) is connected with the innermost sphere (the one that holds the moon) through more than fifty spheres, each with its own movement. Aristotle also spoke of the causes of these rotations. He postulated a series of so called unmoving movers, and at the end of that, the first umoved mover: God. It was through Aristotle that Eudoxus' system became well know in ancient Greece.

A mathematical model that differs from this greatly was formed by Aristarchus.
Presumably merely as a hypothesis he formulated the following theory:
The phenomena that we see in the heavens can also be explained by assuming that the earth is rotating around an axle and rotates around the sun in a circular orbit.

This hypothesis sure surprised me. Nobody took it serious I think, which is quite a pity. My idea for this topic d the following question:
"What do you think is the reason that people decided on the geocentric model instead of the heliocentric model?"

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@Arjen,

Arjen,

I think the reason for accepting the geocentric model is that it was apparent reality, the sun seem to rotate the world, the world seem to be flat ect...,. It is what is given to a limited perception, a limited imagination.

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@boagie,

On the contrary, Archimedes figured out that the Earth was not only a sphere, but also remarkably close estimates on the size of the Earth, by measuring shadows cast at the same time of day a couple hundred miles apart.

I think they were just assuming incorrectly.

I also wonder how much the world lost when the Great Library of Alexandria burned. And what the progress of man might have been with all that knowledge to build upon.

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@Arjen,

But why do you think they "just assumed incorrectly"?

p.s. I can make some quite accurate guesses on what was in the library and why it had to go. A topic on this would be quite nice I think.

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@Arjen,

Arjen,

"Just assumed incorrectly"? and acceptining apparent reality at face value seem to be pretty much the same thing. In the past you have to consider as well that any new knowledge about the world was a direct threat to the church,as it is today. The only difference is the level of the power of the church, in the past was absolute. Keep in mind the Christian faith has not absorbed any new knowledge in over two thousand years.:eek:

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@boagie,

boagie wrote:

Arjen,

"Just assumed incorrectly"? and acceptining apparent reality at face value seem to be pretty much the same thing. In the past you have to consider as well that any new knowledge about the world was a direct threat to the church,as it is today. The only difference is the level of the power of the church, in the past was absolute. Keep in mind the Christian faith has not absorbed any new knowledge in over two thousand years.:eek:

C'mon Boogie, everything doesn't have boil down to your crusade against Christians. In ancient Greece there were no Christians, there was no Church, there were Temples to scores of gods for all occasions with no centralization.
Had the topic been about Galileo or Keppler, and Astronomy in the Renaissance, THEN the smear could be understood and on topic, with some merit.
... but this, I know you can do better.

Arjen, I think its as basic as a childhood notion and perception. As a child they saw the sun "rise and fall". .... with the moon and the cosmos following. They perceived they were standing on a plane, and perceived the heavenly bodies move in an arc above them. They felt no motion, but observed the other celestial bodies moving overhead.
They had no clue, they were standing on a sphere, in fact on the side of a sphere, spinning at 24,000 mph... ect, because they couldnt feel the motion.

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@Irishcop,

You guys inspire me:
[offtopic]

Monty Python wrote:

Just remember that you're standing on a planet that's evolving
And revolving at nine hundred miles an hour,
That's orbiting at nineteen miles a second, so it's reckoned,
A sun that is the source of all our power.
The sun and you and me and all the stars that we can see
Are moving at a million miles a day
In an outer spiral arm, at forty thousand miles an hour,
Of the galaxy we call the 'Milky Way'.
Our galaxy itself contains a hundred billion stars.
It's a hundred thousand light years side to side.
It bulges in the middle, sixteen thousand light years thick,
But out by us, it's just three thousand light years wide.
We're thirty thousand light years from galactic central point.
We go 'round every two hundred million years,
And our galaxy is only one of millions of billions
In this amazing and expanding universe.

The universe itself keeps on expanding and expanding
In all of the directions it can whizz
As fast as it can go, at the speed of light, you know,
Twelve million miles a minute, and that's the fastest speed there is.
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth,
And pray that there's intelligent life somewhere up in space,
'Cause there's bugger all down here on Earth.

[/offtopic]

Allthough I think that Irishcop's remark on Christianity is well put I would like to extrapolate on Boagie's remark. I understand his point of view. I have always felt more or less the same. I do not hold anything against christians, but the institution itself is corrupt as can be. All institutions seem to be corrupt for that matter. I can only assume that religion back then fulfilled the same function it does today: to give us some structure in our lives. After a while these institutions begin to decieve the populace however, seemingly worried for the welfare of said populace (or themselves) if it would become known that the institutions don't know what the h#$$ they are doing either.

I wonder if indeed the "church" (read: temples..religious institutions) are pivital in this. What do you guys think?

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@Arjen,

Arjen,

I think the supression of new knowledge is a definate function of certain belief systems, it is certainly true of Christianity and Islam, though I do not believe it is universal with all faiths. It is true that during the golden age of Greece there were no Christians, I suspect if there were Christians there would have been nothing golden about it.

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Ancient Greece - Movements of Heavenly Bodies.

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