Tuesday, August 23, 2011

More fixed earth

There is more information about the geocentric theory here. This suggests a problem. The original motivation for the geocentric theory was its apparent simplicity, given that the heliocentric theory requires an extra assumption – a tilted earth – to explain the seasons. But it turns out the geocentric theory also needs an extra assumption to explain the seasons, and the apparent motion of the sun that corresponds to this.

A good way to imagine this is to look at a potters wheel as it turns . . . it turns once every 24 hours . . . at the center is the Earth . . . place your finger in the clay, you make a circle, this is the sun . . . now slowly move your finger out 3% of the radius of your first circle . . . now move your finger inward 3% . . . that is the motion of the sun albeit the sun would also move in a spiral helix up and down while it is moving out and in by 3% of the radius . . . there are two motions here, one is up then down the other is in then out again. So there is the spiral up and down motion to account for the seasons but the size of the spiral is constantly changing to account for changes in the distance over the course of a year.
Yes but why does the sun move that way? The assumption of a tilted earth plus gravity seems a simpler explanation and thus (pace Dr Connolley) should be preferred. Obviously the underlying rationale for neo-geocentricism (‘neo-geo’) is the Bible and God, but that raises another question: is God fair? It seems unfair to create a universe whose nature seems almost designed to be misunderstood, once observed carefully. Observations by Galileo and other astronomers, phenomena like Foucault’s pendulum, and many other observable phenomena, suggest a reality that is quite different from the literal truth of the Bible. Geological observations suggest the Earth is much older than 6,000 years. Why did God create the Earth in a way that seems almost designed to mislead? Why did God create dinosaur bones, without mentioned dinosaurs in the Bible? Was that fair of God?

It could be replied that, correctly understood (where correct understanding means theories like ‘neo-geo’), these phenomena do not contradict the literal truth of the Bible. But then, clearly, many millions or billions of people, including all eminent scientists since Galileo’s time, have not correctly understood the evidence. Was it fair of God to create a world whose true nature misled so many brilliant people?

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5 Comments:

Blogger Bill Wallace said...

I think you should check out the rest of that web site you linked to. It is seriously wacko.

6:32 am  
Blogger Edward Ockham said...

>>It is seriously wacko.

I prefer 'logically challenged'. This blog is primarily concerned with logic and scientific method. So we are interested in the question of where the logic of such websites falls down, rather than other idiosyncracies.

7:13 am  
Blogger Belette said...

I don't think logic gets you anywhere here. This is a matter of physics / astronomy / cosmology.

People used to think that you could do cosmology by logic - I think if you look you'll find stuff pretending to demonstrate from first principles that space of Euclidean. That all rather fell apart when General Relativity showed that it wasn't. But while there is a lot of logic in GR it does depend fundamentally on observations: constancy of speed of light, and the equivalence principle. You cannot deduce it from first principles.

That is the first problem. The second is that all the geocentric debate is constantly phrased in terms of what is "really" happening. Does the earth "really" rotate around the sun, or vice versa. Again, people used to think this meant something.

Nowadays (as I understand it) the situation is (again, GR) that you can take whatever you like as your coordinate system. Some systems will give you simpler equations for certain problems, some for others.

For example, if you wish to discuss the movement of a boat on a river, you might take the earth to be fixed, or maybe the river. You'd be mad to take the system with the sun fixed. If you want to look at planetary orbits, you'd be mad to take to coord system with the center of the galaxy fixed.

If you want to discuss planetary orbits, you can if you choose take the earth to be fixed. But this makes all the planetary orbits very complex, and the equations governing them end up with weird forces in them. If you transform to a coord system with the sun fixed (or more accurately the barycenter fixed) then your equations dramatically simplify. People loosely talk of that as meaning that the sun fixed is "true".

The massive difference, now, over say Copernican days is that the observations and calculating ability we have are so much better than before. It is no longer possible to believe in epicycles, because observations demonstrate clearly that they don't work, except in the trivial sense that any path can be fit by enough epicycles to an arbitrary degree of precision.

8:30 am  
Blogger Edward Ockham said...

I don't think logic gets you anywhere here. This is a matter of physics / astronomy / cosmology.

>>People used to think that you could do cosmology by logic - I think if you look you'll find stuff pretending to demonstrate from first principles that space of [sic] Euclidean.

You can certainly find stuff like that, and I studied this years ago. But any such demonstration is logically flawed, and so we come back to logic. From memory, many people attempted to prove the parallel postulate from the first four postulates. At some point, someone demonstrated that this postulate was logically independent of the others, and so non-Euclidean geometry was born.

>>That all rather fell apart when General Relativity showed that it wasn't.

It could only show that it wasn’t because the parallel postulate was logically independent of the others. That opened up the possibility that the postulate was false, which GR eventually showed.

>>But while there is a lot of logic in GR it does depend fundamentally on observations: constancy of speed of light, and the equivalence principle. You cannot deduce it from first principles.

Agreed.

10:17 am  
Blogger Edward Ockham said...

>>That is the first problem. The second is that all the geocentric debate is constantly phrased in terms of what is "really" happening. Does the earth "really" rotate around the sun, or vice versa. Again, people used to think this meant something.

Yes, and that’s a logical question. Much of my doctoral thesis was a study of the history of relativity. Poincare contributed a lot to this. But also Leibniz, centuries earlier. Leibniz asked whether it made any sense to ask whether the world was created 10 years earlier than it actually was. Or whether we could move the whole universe a mile in one direction. And even before that we have Ockham, who constantly invokes the idea that God, in his infinite power, could have created things very differently. These are all thought experiments – not scientific experiments - establishing relativity, or relativistic ideas. The empirical confirmation of these ideas came later.

>>If you want to discuss planetary orbits, you can if you choose take the earth to be fixed. But this makes all the planetary orbits very complex, and the equations governing them end up with weird forces in them.

This is the issue. The argument used by the fixed earth website is that the heliocentric model requires a number of further assumptions (beyond the assumption that the earth is rotating) to explain the observed heavenly motions. But (and here they are correct) any theory that requires fewer assumptions to buttress the initial hypothesis should be preferred to one which requires more. This principle is perfectly correct. However, they neglect to mention that their own theory (fixed earth) requires many more additional supporting assumptions, than the rotating earth one. For example, the rotating earth model requires only the assumption of a tilted axis in order to explain the seasons. That is simple and plausible. The fixed earth model, requires the assumption that the sun moves on a helical ‘rail’, like a bowling alley gutter, that forces it to move round in a skewed way. The question then arises, why was the rail designed in that shape? If the reply is, that is how God willed it, there are a number of problems. (1) invoking supernatural forces is not a simple option – a theory of God or of demons is likely to be highly complex (2) we have to explain precisely why God designed that particular route for the sun (3) a further problem of why he designed it so that even elementary rational thought would suggest a simpler explanation that does not require God.

On the last point, generally, why did God design the universe in such a way that, to an enquiring, observing, rational and intelligent mind, the explanation that naturally occurs is one which rules out God entirely? That suggests God is not fair, and that he has it in for inquisitive and intelligent minds.

>>The massive difference, now, over say Copernican days is that the observations and calculating ability we have are so much better than before. It is no longer possible to believe in epicycles, because observations demonstrate clearly that they don't work, except in the trivial sense that any path can be fit by enough epicycles to an arbitrary degree of precision.

See my point above. Why did God design the heavenly motion in such a way that precise observation and mathematics would suggest a simpler explanation than God? That seems perverse. Why did he not design the universe itself in a way that was consistent with the explanation he provides by the Word of God (the Bible).

10:17 am  

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