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Post by merkavah12 on Jan 12, 2014 22:31:45 GMT
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Post by fortigurn on Jan 13, 2014 4:54:58 GMT
I bet it's that lunatic Sungenis and his mob. Move along, nothing to see here.
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Post by wraggy on Jan 13, 2014 7:04:55 GMT
I bet it's that lunatic Sungenis and his mob. Move along, nothing to see here. Yep, you are right. At least someone was impressed. Can we expect a sequel to this program? Cosmas Indicopleustes Was Right. The Earth Really is Flat. |
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Post by ignorantianescia on Jan 13, 2014 8:10:15 GMT
Can we expect a sequel to this program? Cosmas Indicopleustes Was Right. The Earth Really is Flat.Maybe this would be an even better sequel: ( www.geocentrismdebunked.org/link) |
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Post by chavoux on Jul 8, 2015 21:25:07 GMT
OK, here is a question that has been troubling me for a while (I am not a physicist): if I understand Einstein correctly there is no longer anything like a privileged frame of reference. Doesn't that mean that using the earth as your stationary point is just as valid as using the sun (or the common centre of gravity of the solar system)? So why is it any longer an issue to use the earth as your stationary point rather than the sun (except probably for simpler equations)? What am I missing here?
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Post by unkleE on Jul 8, 2015 23:16:32 GMT
I reckon it is simple mathematics. It is easy to write an equation for the movement of earth and other planets around the sun with the sun as origin, but not so easy to write an equation for the movement of Mars with earth as the origin.
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Post by chavoux on Jul 10, 2015 12:22:06 GMT
OK, but that I also agreed with (simpler maths). But does the fact that it gives simpler mathematics, really imply that it is truer? E.g. two trains speeding toeards each other could be also described as one of them being stationary and the other moving at a higher speed (the sum of the original speeds) towards it, resulting in simpler maths. But is it therefore any more true? Indeed, if I want to calculate a meaningful maximum speed of a train, I will be forced to use the earth as my reference point, rather than the other train, even if it results in more complex maths.
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kj
Clerk
Posts: 9 
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Post by kj on Jul 11, 2015 19:08:59 GMT
It's not merely that the mathematics is simpler- the physical laws become consistent. By putting the sun in the center, all of the planets obey the same laws of motion (Kepler's laws, which led to Newton's generalizations, and so on). The moon goes around the earth by obeying the same laws. It is worth noting that one of Kepler's laws is basically a statement of conservation of angular momentum, and conservation laws are crucial to the modern formulation of mechanics (cf. Noether's theorem).
If we insist on a geocentric system, we can, of course formulate kinematic equations to describe the positions of the sun and the planets. But we have a much harder time unifying the dynamics of motion: moons go around planets in elliptical orbits, but planets precess (follow epicyclic orbits) about points which go around the earth. There is no clear reasoning for the periods or radii of these epicycles- they are simply determined by observation. Which works- Ptolemy's model did a very good job of predicting the positions of planets. As has been observed previously on this site, that was part of Galileo's problem. But it's not easily generalizable, and it has no associated simple conservation law (angular momentum is still conserved, but the description of angular momentum in geocentric coordinates is nontrivial).
Does it mean it's absolutely correct? Of course not- we have no way of knowing what "absolutely correct" is. Newtonian gravity is not believed to be the correct model, being replaced by general relativistic descriptions of gravity as a geometric effect, and not a simple force acting between bodies. As for "more correct," I don't know quite how to measure correctness, but it seems to me reasonable to use "capable of explaining a larger number of phenomena with a single formalism/description." Given that metric, it is more correct to consider the earth as moving than a geocentric system.
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Post by ignorantianescia on Jul 12, 2015 12:58:04 GMT
OK, here is a question that has been troubling me for a while (I am not a physicist): if I understand Einstein correctly there is no longer anything like a privileged frame of reference. Doesn't that mean that using the earth as your stationary point is just as valid as using the sun (or the common centre of gravity of the solar system)? So why is it any longer an issue to use the earth as your stationary point rather than the sun (except probably for simpler equations)? What am I missing here? You aren't missing anything. Since relativistic physics, both frames are equally arbitrary. You need to keep your eye on additional rotations in both of these options (if your frame of reference is the Sun, it is still influenced by space-time distortions from the planets for instance). There isn't any centre in the universe. |
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Post by himself on Jul 27, 2015 2:52:38 GMT
Up until Galileo's time, the only interest was in "saving the appearances." That is, astronomers were specialized mathematicians, and the only purpose of their models was to accurately predict the motions in the heavens for the benefit of astrologers and calendar-makers (and later, navigators). With the telescope came the discovery that the heavenly bodies were physical places about which physical statements could be made, and astronomy began to transition from the math dept. to the physics dept.
The principle of relativity, developed by Witelo, was used by Nicholas Oresme to show that naive observation was not sufficient to distinguish between a stationary and a mobile earth. To make the distinction, different kinds of data would be needed; ult. stellar aberration, parallax, and Coriolis.
While one may say there is no privileged frame of reference for inertial motion, the addition of revolution introduces accelerated motion, and this alters cases. (Basically, mass distorts the field of Ricci tensors and creates "dimples" in space-time. The geodesics on this manifold are then curved around the largest mass in the vicinity, if that mass is overwhelming in size. That's why solutions to planetary motions first account for the effect of the Sun, next for Jupiter, and so on. Distance is also a factor: a trip to the Moon must take account of the Earth, the Sun and the Moon.)
Think of a kid on a merry-go-round. The kid might easily imagine that he is sitting still while the park revolves around him. (Watch various TV shows with camera-views attached to a moving vehicle when that vehicle spins out or tumbles.) You might even devise a system of calculations to that effect; but no one but a lunatic would suppose that the carousel revolves around the kid, relativity or no.
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