Is heliocentrism wrong?
April 28, 2008 2:26 AM Subscribe
Does modern science prove the theory of heliocentrism wrong?
In 1990, in a defense of the church's actions toward Galileo, Cardinal Ratzinger references Marxist philosopher Ernst Bloch in order to demonstrate that the Theory of Relativity has proven heliocentrism wrong. Here is an excerpt:
My question is purely about the science behind this statement and the rest of the commentary in Ratzinger’s article. Forget about whether the church should be persecuting scientists in the first place. I want to know, does modern science prove Galileo wrong?
The planets revolve around the sun. The reason why geocentrism makes bad predictions is because it is wrong. This is what I thought while reading this article, but as I have such a hard time understanding the theory of relativity, perhaps I am missing something or do not quite understand what Bloch is implying with his statements. I would appreciate it if someone with a better understanding of science could clear this up for me. Thanks!
In 1990, in a defense of the church's actions toward Galileo, Cardinal Ratzinger references Marxist philosopher Ernst Bloch in order to demonstrate that the Theory of Relativity has proven heliocentrism wrong. Here is an excerpt:
According to [Ernst] Bloch, the heliocentric system – just like the geocentric – is based upon presuppositions that can’t be empirically demonstrated. Among these, an important role is played by the affirmation of the existence of an absolute space; that’s an opinion that, in any event, has been cancelled by the Theory of Relativity. Bloch writes, in his own words: ‘From the moment that, with the abolition of the presupposition of an empty and immobile space, movement is no longer produced towards something, but there’s only a relative movement of bodies among themselves, and therefore the measurement of that [movement] depends to a great extent on the choice of a body to serve as a point of reference, in this case is it not merely the complexity of calculations that renders the [geocentric] hypothesis impractical? Then as now, one can suppose the earth to be fixed and the sun as mobile.”From here.
My question is purely about the science behind this statement and the rest of the commentary in Ratzinger’s article. Forget about whether the church should be persecuting scientists in the first place. I want to know, does modern science prove Galileo wrong?
The planets revolve around the sun. The reason why geocentrism makes bad predictions is because it is wrong. This is what I thought while reading this article, but as I have such a hard time understanding the theory of relativity, perhaps I am missing something or do not quite understand what Bloch is implying with his statements. I would appreciate it if someone with a better understanding of science could clear this up for me. Thanks!
interesting question. i'm not a scientist, though. and certainly not a physicist.
but it seems what the ratzinger is saying is that it's "all a matter of perspective." that since everything in the universe is moving, it is arbitrary what you choose as the "center".
while that may be, our understanding of gravity does (to my limited knowledge) prove that the planets in our solar system are held in orbit around the sun. one could make a model of the universe in which Earth were the fixed point, but the motion-map would still show planets orbiting the Sun.
as to Einstein's theory of Relativity; i believe he's referencing the idea of curved space/time. but that's again just another muddling and not a particularly relevant one. it's like saying "that's a nice blue sweater, but since you can't see in infrared, you don't realize it's actually a map to plartorn-12"; in terms or our understanding of temporal reality, the solar system is heliocentric. if we understand parallel universes at some later date (cool!), maybe that will drastically alter our perceptions.
um. i think that's all correct. i'm interested to hear what others have to say.
as to what ratzinger's point is... he's saying the church might not have been wrong. it's pretty lame imho. like saying feeding you to a tiger was good in the long run as now tigers are endangered!
posted by xz at 3:01 AM on April 28, 2008
but it seems what the ratzinger is saying is that it's "all a matter of perspective." that since everything in the universe is moving, it is arbitrary what you choose as the "center".
while that may be, our understanding of gravity does (to my limited knowledge) prove that the planets in our solar system are held in orbit around the sun. one could make a model of the universe in which Earth were the fixed point, but the motion-map would still show planets orbiting the Sun.
as to Einstein's theory of Relativity; i believe he's referencing the idea of curved space/time. but that's again just another muddling and not a particularly relevant one. it's like saying "that's a nice blue sweater, but since you can't see in infrared, you don't realize it's actually a map to plartorn-12"; in terms or our understanding of temporal reality, the solar system is heliocentric. if we understand parallel universes at some later date (cool!), maybe that will drastically alter our perceptions.
um. i think that's all correct. i'm interested to hear what others have to say.
as to what ratzinger's point is... he's saying the church might not have been wrong. it's pretty lame imho. like saying feeding you to a tiger was good in the long run as now tigers are endangered!
posted by xz at 3:01 AM on April 28, 2008
What he's trying to say, I think, is that modern science holds that everything is moving though space, even our sun, even our galaxy. Because of that, the entire notion of something being fixed in space no longer holds. So the debate between whether the earth is fixed in space, and the planets move in some extremely complex way around it (geocentrism), or whether the sun is fixed in space, and the planets move around it (heliocentrism), really just goes away (because nothing is fixed in space).
What everything boils down to, then, is just points of reference. From the point of reference of the sun, the planets revolve around it. But, you could do out the calculations and translate that point of reference to the earth's to find equations for how each body in our solar system revolves relative to the earth, as well. With those equations, we might suppose the earth is the center.
IANAA - I am not an astrophysicist, but I did just take a class where we talked about Galileo and this general sort of thing. On preview, also everything nasreddin said. Part of Galileo's argument was that the only thing that could make all the water in the oceans slush about so much as to create the tides was the movement of the earth, but it's actually the moon.
posted by Galt at 3:03 AM on April 28, 2008
What everything boils down to, then, is just points of reference. From the point of reference of the sun, the planets revolve around it. But, you could do out the calculations and translate that point of reference to the earth's to find equations for how each body in our solar system revolves relative to the earth, as well. With those equations, we might suppose the earth is the center.
IANAA - I am not an astrophysicist, but I did just take a class where we talked about Galileo and this general sort of thing. On preview, also everything nasreddin said. Part of Galileo's argument was that the only thing that could make all the water in the oceans slush about so much as to create the tides was the movement of the earth, but it's actually the moon.
posted by Galt at 3:03 AM on April 28, 2008
Most science is a sequence of approximations which are refined over time. Galileo correctly identified that the planets of the solar system appear to move around the sun, and so a heliocentric model 'worked' more readily (i.e. required less complex geometry) than a geocentric model.
Much later, relativity indicated that there are no special points of reference. This says little about geocentrism or heliocentrism except that neither the earth nor the sun is a special point of reference. We're free to choose any body as a 'centre' for the purposes of calculation, but any choice we make is purely one of convenience.
To say that Galileo was 'wrong' to take a heliocentric view is a little like saying Newton's mechanics were 'wrong'. Science is more about getting a good model for physical behaviour than it is about an absolute idea of 'right' or 'wrong'. In their respective times the geocentric and heliocentric models both made sense in terms of our understanding of the universe, although admittedly in the first case this understanding was largely a religious one.
posted by le morte de bea arthur at 3:04 AM on April 28, 2008 [3 favorites]
Much later, relativity indicated that there are no special points of reference. This says little about geocentrism or heliocentrism except that neither the earth nor the sun is a special point of reference. We're free to choose any body as a 'centre' for the purposes of calculation, but any choice we make is purely one of convenience.
To say that Galileo was 'wrong' to take a heliocentric view is a little like saying Newton's mechanics were 'wrong'. Science is more about getting a good model for physical behaviour than it is about an absolute idea of 'right' or 'wrong'. In their respective times the geocentric and heliocentric models both made sense in terms of our understanding of the universe, although admittedly in the first case this understanding was largely a religious one.
posted by le morte de bea arthur at 3:04 AM on April 28, 2008 [3 favorites]
[[Galileo]] is helpful. Noting the other planets, with their own orbital periods & moons, comes to mind. I can't imagine how comets & galaxies would be accounted for.
Browsing Wikipedia, it looks like epicycles were used, but inaccurate with regard to the other bodies of the solar system.
posted by Pronoiac at 3:12 AM on April 28, 2008
Browsing Wikipedia, it looks like epicycles were used, but inaccurate with regard to the other bodies of the solar system.
posted by Pronoiac at 3:12 AM on April 28, 2008
Seconding "le morte de bea arthur". Galileo wasn't "wrong", because heliocentrism provided a better model, meanwhile Copernic was proposing an heliocentric model and Kepler was deriving his laws from Tycho's observations, Tycho himself adapting the geocentric model to a geo-heliocentric model of his own.
Ptolemy's geocentric model, with epycicles was fairly accurate, but could not hold in front of Galileo's observation of Venus' phases, which would have implied that the celestial spheres were compenetrating.
In this, and the fact that Galileo introduced the Relativity principle in science, which ultimately brought to the foundation of the scientific method, lies the ultimate consequence: for science, truth is somewhere between here and transcendence, and Man can try and find it, something that undermines deeply the scientific (or sometimes pseudo-scientific) theological constructs.
Orazio Grassi, a church mathematician, tried, during Galileo's trial, to reaffirm geocentrism on the basis of observation and a very convolute scholastic argument, ultimately failing (but at the time he was fairly successful, nevertheless).
The geocentric model held for roughly 15 centuries, while heliocentrism is "just" 400 years old. Nevertheless, geocentrism was holding at the moment: during the trial, the church would not veto Galileo's (or Copernicus') theses, but would ask for them to be considered a mathematical, abstract construct "until the definitive proof".
In the 1990 passage, besides Bloch, Ratzinger was reprising Feyerabend, who said that (I quote from memory) "The Church, in Galileo's time, was more rational than Galileo himself, so his trial was reasonable and just".
"But", Ratzinger added, "building a hasteful apologetic thesis on these affirmations alone would be absurd: faith does not grow from resentment and refusal of rationality, but from its fundamental acceptance and its inscription in a greater reason".
(sorry if i went on a tangent)
posted by _dario at 4:31 AM on April 28, 2008
Ptolemy's geocentric model, with epycicles was fairly accurate, but could not hold in front of Galileo's observation of Venus' phases, which would have implied that the celestial spheres were compenetrating.
In this, and the fact that Galileo introduced the Relativity principle in science, which ultimately brought to the foundation of the scientific method, lies the ultimate consequence: for science, truth is somewhere between here and transcendence, and Man can try and find it, something that undermines deeply the scientific (or sometimes pseudo-scientific) theological constructs.
Orazio Grassi, a church mathematician, tried, during Galileo's trial, to reaffirm geocentrism on the basis of observation and a very convolute scholastic argument, ultimately failing (but at the time he was fairly successful, nevertheless).
The geocentric model held for roughly 15 centuries, while heliocentrism is "just" 400 years old. Nevertheless, geocentrism was holding at the moment: during the trial, the church would not veto Galileo's (or Copernicus') theses, but would ask for them to be considered a mathematical, abstract construct "until the definitive proof".
In the 1990 passage, besides Bloch, Ratzinger was reprising Feyerabend, who said that (I quote from memory) "The Church, in Galileo's time, was more rational than Galileo himself, so his trial was reasonable and just".
"But", Ratzinger added, "building a hasteful apologetic thesis on these affirmations alone would be absurd: faith does not grow from resentment and refusal of rationality, but from its fundamental acceptance and its inscription in a greater reason".
(sorry if i went on a tangent)
posted by _dario at 4:31 AM on April 28, 2008
Piling on here...
If so, it's just the normal progression of successively improved scientific hypothesis. Today's explanations are framed in terms of today's knowledge, with less useful theory discarded.
(Ratzinger and his church could learn a lot from that technique, but then, they'd have to have a liquidation sale on the church!)
Once you discard the quaint and homo-centric version of things that suggests the Earth to be the center of the universe, it is just as conceited to postulate that the Sun is. It's the local center of things, as our relative motion with respect to it has more immediate impacts on our lives than anything else in the cosmos. Calling it heliocentric is a practical summation, and incidentally, it's not a heliocentric UNIVERSE, it's a heliocentric solar system. In that regard, Galileo is not wrong, nor is he first.
Heliocentrism predates Galileo substantially. The ancients were lots smarter than Christian Europeans. Archimedes estimated the number of grains of sand in the visible universe in a letter called "The Sand Reckoner". That was MILLENIA before Galileo. In it, HE refers the the ancients. Pretty sobering for folks who think we moderns know it all, huh?
posted by FauxScot at 4:35 AM on April 28, 2008
If so, it's just the normal progression of successively improved scientific hypothesis. Today's explanations are framed in terms of today's knowledge, with less useful theory discarded.
(Ratzinger and his church could learn a lot from that technique, but then, they'd have to have a liquidation sale on the church!)
Once you discard the quaint and homo-centric version of things that suggests the Earth to be the center of the universe, it is just as conceited to postulate that the Sun is. It's the local center of things, as our relative motion with respect to it has more immediate impacts on our lives than anything else in the cosmos. Calling it heliocentric is a practical summation, and incidentally, it's not a heliocentric UNIVERSE, it's a heliocentric solar system. In that regard, Galileo is not wrong, nor is he first.
Heliocentrism predates Galileo substantially. The ancients were lots smarter than Christian Europeans. Archimedes estimated the number of grains of sand in the visible universe in a letter called "The Sand Reckoner". That was MILLENIA before Galileo. In it, HE refers the the ancients. Pretty sobering for folks who think we moderns know it all, huh?
posted by FauxScot at 4:35 AM on April 28, 2008
I'm wondering where the Bloch quote ends, because everything seems fine up to this:
"...in this case is it not merely the complexity of calculations that renders the [geocentric] hypothesis impractical? Then as now, one can suppose the earth to be fixed and the sun as mobile.”
One of the postulates of special relativity is that there are no preferred inertial reference frames. That is, we can't tell anything about our velocity by doing experiments -- so long as our velocity is constant. (The word 'inertial' is what restricts the postulate to constant velocities.) And velocity is a vector quantity, so velocity is constant only if direction is constant as well as speed. The velocity of the earth changes as the earth orbits the sun, because the direction of motion of the earth changes. (The speed of the earth also changes, but only very slightly.) We can do experiments that tell us when our velocity changes.
So if we sit here on the surface of the earth and ask ourselves "Is the sun going around us or does it only seem that way because we are spinning?" we can do an experiment to see if we are spinning. Because if we are spinning then our direction of motion is constantly changing, and we are no longer in an inertial reference frame. Foucault's pendulum is an example of an experiment that tells us that the earth is spinning.
posted by Killick at 5:47 AM on April 28, 2008 [1 favorite]
"...in this case is it not merely the complexity of calculations that renders the [geocentric] hypothesis impractical? Then as now, one can suppose the earth to be fixed and the sun as mobile.”
One of the postulates of special relativity is that there are no preferred inertial reference frames. That is, we can't tell anything about our velocity by doing experiments -- so long as our velocity is constant. (The word 'inertial' is what restricts the postulate to constant velocities.) And velocity is a vector quantity, so velocity is constant only if direction is constant as well as speed. The velocity of the earth changes as the earth orbits the sun, because the direction of motion of the earth changes. (The speed of the earth also changes, but only very slightly.) We can do experiments that tell us when our velocity changes.
So if we sit here on the surface of the earth and ask ourselves "Is the sun going around us or does it only seem that way because we are spinning?" we can do an experiment to see if we are spinning. Because if we are spinning then our direction of motion is constantly changing, and we are no longer in an inertial reference frame. Foucault's pendulum is an example of an experiment that tells us that the earth is spinning.
posted by Killick at 5:47 AM on April 28, 2008 [1 favorite]
I'm with le morte de bea arthur. Science improves over time, but that doesn't necessarily mean we throw out the old models completely if they're actually good approximations to the real world. We still keep the Bohr of the atom around because it's remarkably simple and elegant, and gives reasonable results to first order. We use it as a teaching tool, and as an approximation tool. It's not as accurate as quantum mechanics, and arguably doesn't reflect the real world, but it's a model, and you also don't want to show operators to freshmen. Similarly, heliocentrism is oversimplified (and, of course, in its fullest extent says that the sun is the center of the universe, so that part has to be thrown out), but it's still pretty good in some ways. In reality the sun and the earth rotate about their common center of mass, but the sun is so much more massive that the center of mass's location is negligibly far from the sun for any daily uses. If you're plotting a course for your rocket to Mars, yes, it might matter, but I think heliocentrism is still a pretty good argument for telling your kids that the earth goes around the sun.
posted by you're a kitty! at 6:19 AM on April 28, 2008
posted by you're a kitty! at 6:19 AM on April 28, 2008
I'm also wondering if this quote is incorrectly attributed. It sounds like something that might have come from Ernst Mach.
posted by Killick at 6:27 AM on April 28, 2008
posted by Killick at 6:27 AM on April 28, 2008
Paging The Bad Astronomer! You might find some info here.
posted by Guy_Inamonkeysuit at 6:42 AM on April 28, 2008
posted by Guy_Inamonkeysuit at 6:42 AM on April 28, 2008
To be super precise about our local solar system: everything (all planets, the sun, asteroids, etc.) orbit around the center of mass of the solar system. We wobble the sun.
posted by Netzapper at 6:55 AM on April 28, 2008
posted by Netzapper at 6:55 AM on April 28, 2008
Well yes, Copernicus and Galileo were both badly wrong, so wrong that if Kepler had given into the desire to fudge the Mars data collected by Tycho, western astronomy would have been fucked for a good couple of centuries. The Copernican model was still grounded in the belief in idealized shapes and spheres.
But, the absence of a single inertial frame of reference doesn't necessarily mean we can say that everything moves around an arbitrary point. You still have to deal with acceleration ~ Force/mass in both Newtonian and Relativistic frameworks (using a tilde because it's not linear under Relativity). Applying this to the Earth and the Sun: the Sun's mass is 2e30kg, and the Earth's mass is 6e24kg. The acceleration of the Sun relative to the Earth is minimal. The acceleration of the Earth relative to the Sun is large.
posted by KirkJobSluder at 7:49 AM on April 28, 2008 [1 favorite]
But, the absence of a single inertial frame of reference doesn't necessarily mean we can say that everything moves around an arbitrary point. You still have to deal with acceleration ~ Force/mass in both Newtonian and Relativistic frameworks (using a tilde because it's not linear under Relativity). Applying this to the Earth and the Sun: the Sun's mass is 2e30kg, and the Earth's mass is 6e24kg. The acceleration of the Sun relative to the Earth is minimal. The acceleration of the Earth relative to the Sun is large.
posted by KirkJobSluder at 7:49 AM on April 28, 2008 [1 favorite]
There is a school of thought out there which resents the recent success of science, and wishes to use various relativistic arguments to suggest that physics is really no more than a matter of opinion and preference. In my view this school should be energetically resisted. It seems Ratzinger believes he can hitch a ride with it, but he should recognise that befriending radical scepticism is an odd and dangerous thing for any Catholic to do.
Yes, it is merely the complexity of the calculations which makes us reject the Ptolemaic system, but that's because if your belief involves fantastic complications, it's a good sign your belief is wrong.
Yes, Galileo's theory was just an approximation, but it was better than what went before. The fact that we now know space is not absolute does mean he was wrong, but it does not mean the medieval view with Earth as absolute centre and crystal spheres all around was OK after all: it means it was even wronger than we knew.
posted by Phanx at 9:03 AM on April 28, 2008 [1 favorite]
Yes, it is merely the complexity of the calculations which makes us reject the Ptolemaic system, but that's because if your belief involves fantastic complications, it's a good sign your belief is wrong.
Yes, Galileo's theory was just an approximation, but it was better than what went before. The fact that we now know space is not absolute does mean he was wrong, but it does not mean the medieval view with Earth as absolute centre and crystal spheres all around was OK after all: it means it was even wronger than we knew.
posted by Phanx at 9:03 AM on April 28, 2008 [1 favorite]
The geocentric model of the solar system was sufficient for a long time. Epicycles were added to account for observations that didn't match the theory. Epicycles were added to epicycles as better data accrued.
The heliocentric model of the solar system required no ad hoc addition (epicycles) to account for the best data.
A relativistic view of the universe does not deprecate the heliocentric model of the solar system. The math for plotting orbits is simple enough for high school science class (I did this, and hope most of you did, too) with a bit a Kepler, a protractor, and graph paper. Any attempt to couch the answer in terms of relativity has as its elegant solution a frame of reference where the sun is stationary with respect to the observer. Thus we're solving for a heliocentric model of the solar system.
As a technique in rhetoric, adopting "no frame of reference is more special than any other" is a facile argument. As a scientist, mathematician, or just common sense human, it's best to always solve a problem by removing the vestigial parts of an equation.
Cardinal Ratzinger implies that a geocentric model is as valid as a heliocentric model because Einstein shows no point of the universe is fixed. No. A geocentric model, even with ad hoc epicycle-upon-epicycle, is demonstrably untrue. The math doesn't work.
That this can be a source of epistemological confusion is troublesome to me. While all frames of spatial reference are equally valid, some frames of reference are a lot more useful than others. Not being able to distinguish between empirically evidenced rationality and, say, "the flying spaghetti monster makes it so" is sad.
posted by lothar at 9:13 AM on April 28, 2008
The heliocentric model of the solar system required no ad hoc addition (epicycles) to account for the best data.
A relativistic view of the universe does not deprecate the heliocentric model of the solar system. The math for plotting orbits is simple enough for high school science class (I did this, and hope most of you did, too) with a bit a Kepler, a protractor, and graph paper. Any attempt to couch the answer in terms of relativity has as its elegant solution a frame of reference where the sun is stationary with respect to the observer. Thus we're solving for a heliocentric model of the solar system.
As a technique in rhetoric, adopting "no frame of reference is more special than any other" is a facile argument. As a scientist, mathematician, or just common sense human, it's best to always solve a problem by removing the vestigial parts of an equation.
Cardinal Ratzinger implies that a geocentric model is as valid as a heliocentric model because Einstein shows no point of the universe is fixed. No. A geocentric model, even with ad hoc epicycle-upon-epicycle, is demonstrably untrue. The math doesn't work.
That this can be a source of epistemological confusion is troublesome to me. While all frames of spatial reference are equally valid, some frames of reference are a lot more useful than others. Not being able to distinguish between empirically evidenced rationality and, say, "the flying spaghetti monster makes it so" is sad.
posted by lothar at 9:13 AM on April 28, 2008
My general distaste of the Rat aside (I am an atheist and thoroughly anti-theist), geocentrism is HIGHLY refutable on scientific grounds. (My qualifications for knowing this, by the way, are being a science student, two semesters of physics, and a history of science class. )
Using the masses of the sun and planets, the Earth does not have the mass to hold the planets and the sun in an orbit, and in fact would be unceremoniously sucked into the sun the instant any orbit like that was formed.
We have calculated the distance of the sun and planets using radio, ultraviolet, infrared, and visible light - not just our eyes - and the mathematics does not support geocentrism.
Think of the galaxy as a series of ellipses: the galactic center is at the center of the spinning circle (a circle is an ellipse whose foci are at the same location , the sun is at one focus of the ellipses created by the planets and rotates on its own, and the planets rotate, albeit in different planes. Everything is affected by the four fundamental forces of the universe.
And any geocentrist I have ever come across doesn't know the science behind any of this. They are usually fundamentalists and complete nutbags.
posted by kldickson at 9:52 AM on April 28, 2008
Using the masses of the sun and planets, the Earth does not have the mass to hold the planets and the sun in an orbit, and in fact would be unceremoniously sucked into the sun the instant any orbit like that was formed.
We have calculated the distance of the sun and planets using radio, ultraviolet, infrared, and visible light - not just our eyes - and the mathematics does not support geocentrism.
Think of the galaxy as a series of ellipses: the galactic center is at the center of the spinning circle (a circle is an ellipse whose foci are at the same location , the sun is at one focus of the ellipses created by the planets and rotates on its own, and the planets rotate, albeit in different planes. Everything is affected by the four fundamental forces of the universe.
And any geocentrist I have ever come across doesn't know the science behind any of this. They are usually fundamentalists and complete nutbags.
posted by kldickson at 9:52 AM on April 28, 2008
> The reason why geocentrism makes bad predictions is because it is wrong.
No. It's a bad theory because it produces bad predictions, not the other way around.
The heliocentric model is better, because it produces better predictions. Whether that means the model is closer to "objective reality" (whatever that is), is an academic point and IMO wankery. It doesn't matter whether it's objectively true or not, the point is that it's predictive.
The only reason models incorporating the Theory of Relativity are better, is that they produce even better predictions still. Arguably, that might make them even closer to 'truth,' but again, that's getting outside the realm of science and into metaphysics/philosophy/religion/masturbation.
Geocentrism sucked because it failed to produce predictions that corresponded to observations. Heliocentrism was an objectively superior predictive model in that its predictions worked without a lot of arm-twisting, and for that Galileo should be lauded. The fact that the Sun isn't the center of the Universe -- that there may not be a "center" to absolute space (or 'absolute space' at all) -- isn't really a legitimate criticism of the model.
Physics consists mostly of models. Those models may correspond to some sort of objective reality, or they may not. We don't know and it doesn't matter. The usefulness of particular models depends entirely on whether they predict observable phenomena and dovetail well with other models that predict observable phenomena. Many physicists assume -- almost as an article of faith -- that the better a model predicts reality, the closer the model is to how reality actually operates. I think that's a bad, or at least unfounded, assumption. Thankfully, it's mostly irrelevant to physics as an everyday discipline.
posted by Kadin2048 at 11:00 AM on April 28, 2008 [2 favorites]
No. It's a bad theory because it produces bad predictions, not the other way around.
The heliocentric model is better, because it produces better predictions. Whether that means the model is closer to "objective reality" (whatever that is), is an academic point and IMO wankery. It doesn't matter whether it's objectively true or not, the point is that it's predictive.
The only reason models incorporating the Theory of Relativity are better, is that they produce even better predictions still. Arguably, that might make them even closer to 'truth,' but again, that's getting outside the realm of science and into metaphysics/philosophy/religion/masturbation.
Geocentrism sucked because it failed to produce predictions that corresponded to observations. Heliocentrism was an objectively superior predictive model in that its predictions worked without a lot of arm-twisting, and for that Galileo should be lauded. The fact that the Sun isn't the center of the Universe -- that there may not be a "center" to absolute space (or 'absolute space' at all) -- isn't really a legitimate criticism of the model.
Physics consists mostly of models. Those models may correspond to some sort of objective reality, or they may not. We don't know and it doesn't matter. The usefulness of particular models depends entirely on whether they predict observable phenomena and dovetail well with other models that predict observable phenomena. Many physicists assume -- almost as an article of faith -- that the better a model predicts reality, the closer the model is to how reality actually operates. I think that's a bad, or at least unfounded, assumption. Thankfully, it's mostly irrelevant to physics as an everyday discipline.
posted by Kadin2048 at 11:00 AM on April 28, 2008 [2 favorites]
In Newtonian gravity, an observer outside a gravitationally bound pair of objects wouldn't say that one orbits the other. Instead, both orbit the barycenter. For the sun and any planet, however, the barycenter lies well within the sun. The earth's mass is 80 times larger than the moon's, but the moon orbits at 60 earth radii, so the their barycenter is inside the earth. The barycenter between Jupiter and its moons lies very deep inside Jupiter. So "the moon orbits the earth," "Jupiter's moons orbit the planet," and "the planets orbit the sun" are excellent approximations.
Since Galileo's time, advances in astronomy have permitted observation of multiple star systems where the barycenter lies far from either object. Against the background of more distant "fixed" stars, these binary stars spiral about this empty point, while the center of mass itself traces a straight line.
Heliocentrism --- "the planets orbit the sun" --- requires fewer gyrations than geocentrism to account for e.g. retrograde motion of the outer planets. But it, too, contains oversimplifications that became apparent only after further observations.
posted by fantabulous timewaster at 10:29 AM on May 1, 2008
Since Galileo's time, advances in astronomy have permitted observation of multiple star systems where the barycenter lies far from either object. Against the background of more distant "fixed" stars, these binary stars spiral about this empty point, while the center of mass itself traces a straight line.
Heliocentrism --- "the planets orbit the sun" --- requires fewer gyrations than geocentrism to account for e.g. retrograde motion of the outer planets. But it, too, contains oversimplifications that became apparent only after further observations.
posted by fantabulous timewaster at 10:29 AM on May 1, 2008
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I would suggest you read Feyerabend's Against Method, which I've recommended before. He goes through all the relevant aspects of the Galileo controversy and shows that, 20/20 hindsight aside, there was no really good reason to prefer heliocentrism at that point--Galileo couldn't prove many of his conjectures, and had to rely on rhetorical trickery to displace geocentrism.
posted by nasreddin at 2:58 AM on April 28, 2008