The Flat Earth Temptation Beckons Still: First Annual 'Catholic' Conference On Geocentrism

[Joanne98]

Galileo Was Wrong, The Church Was Right - that's the sensationalistic heading for the 1st Annual Catholic Conference on Geocentrism.

Geocentrism is the claim that the Sun revolves around the Earth, not vice-versa. From the cast of speakers at this event, I don't get the sense that the geocentric movement is growing, but with young evangelical Christian auteurs making short films about God beaming product-safety alerts directly into the heads of Christian housewives, who knows?



Below is my February 16, 2007 Talk To Action story, Copernicus Was Wrong : Reconstructionism & "The Flat Earth Temptation", in its entirety.



Geocentrists accept a spherical earth but deny that the sun is the center of the solar system or that the earth moves.... The basis for their belief is a literal reading of the Bible. < source >
An emergent scandal over a Texas Republican Party politician's distribution of a memo citing a "fixed Earth" website alleging the Earth does not not rotate and lies at the center of the universe has raised the question; where do such eccentric views as Rep. Chisum's, that the Copernican model of the Solar System is wrong and derives from a Jewish Kabbalistic Conspiracy, come from ?


Until recently, it's been generally assumed that the debate over heliocentric vs. geocentric models of the universe, that raged up until the advent of Copernicus, had been well resolved. Lately though, an American movement has sought to restore the Earth to a central position in the grand cosmological scheme... Since the existence of the "Flat Earth Society" became a widely traveled joke, it has become hard to determine if card-carrying flat-earthers really exist any more; many join the society for amusement.


But, there are real geocentrists who dream of spheres within spheres and orreries, speculate that Copernicus killed Tycho Brahe and write dense, arcane mathematical proofs placing the Earth at the center of it all. Variants of such views apparently can be found in the Texas State legislature and, in 1999, Tom Willis --head of the Mid-Atlantic Creation Research Association-- was " instrumental in revising the Kansas elementary school curriculum to remove references to evolution, earth history, and science methodology" (also see this Washington Post story.)

http://www.talk2action.org/story/2010/9/12/18017/5649

[Sinistrous]

1. Utterly terrifying.

We should note that this nonsense is being fomented by a bunch of non-astronomers.

And I got a sick feeling in my stomach when I noticed that it has the blessing of the Chalcedon Society.

[RKP5637]

2. Ignorance breeds ignorance. n/t

[StandingInLeftField]

3. This is from the Onion, right?

Right?

[Joanne98]

7. Nope

[Jim__]

4. Stephen Hawking's new book lends them some support.

They're not actually proclaiming that the earth is flat, but rather that it's motionless: Geocentrists accept a spherical earth but deny that the sun is the center of the solar system or that the earth moves

In Hawking's new book, he says that each is a model and the advantage of the Copernican model is computational convenience:

A famous example of different pictures of reality is the model introduced around A.D. 150 by Ptolemy (ca. 85–ca. 165) to describe the motion of the celestial bodies. Ptolemy published his work in a treatise explaining reasons for thinking that the earth is spherical, motionless, positioned at the center of the universe, and negligibly small in comparison to the distance of the heavens.

This model seemed natural because we don't feel the earth under our feet moving (except in earthquakes or moments of passion). Ptolemy's model of the cosmos was adopted by the Catholic Church and held as official doctrine for fourteen hundred years. It was not until 1543 that an alternative model was put forward by Copernicus. So which is real? Although it is not uncommon for people to say Copernicus proved Ptolemy wrong, that is not true. As in the case of the goldfish, one can use either picture as a model of the universe. The real advantage of the Copernican system is that the mathematics is much simpler in the frame of reference in which the sun is at rest.

more ...

[Sinistrous]

5. What amazing good luck NASA has had

in having space craft to successfully rendezvous with the other planets in the solar system using the "Optional" Copernican model. :sarcasm:

Geo-centrism is intellectual atavism at its worst.

[Jim__]

6. I tend to take Hawking's opinions on the nature of the cosmos seriously.

Obviously Hawking accepts the Copernican model as correct - i.e. a model that is valid. His statement implies that the Ptolemaic model could be just as valid.

The interesting thing about this statement has nothing really to do with geocentrism, but rather what it implies about the actual state of our knowledge. Our cosmological knowledge allows us to make very accurate predictions; however, predictive capability does not necessarily imply explanatory knowledge. Your post shows both an amazing lack of understanding on this point and an amazing lack of curiousity when a recognized expert challenges your unjustified certainty.

I am fairly certain that Hawking is aware of NASA and its successes in space. However, that knowledge did not prevent his making this statement.

[Sinistrous]

8. Hawking's main point, as I read it

(interpreted through my "amazing lack of curiosity", of course) is that both are "models", and that from our perspective, they "could" both be valid. However, predictive capability is one of the strongest supports for a scientific hypothesis or observation. True, it does not provide absolute certainty, but it comes close and serves as a sound basis for acceptance. My "amazing lack of understanding on this point" seems to stem from your expansive ego and your tagging along on the Hawking bandwagon.

Geo-centrism is still codswallop. Here's a little quiz: There are countless stars in the known universe. Name one that has been found that orbits around a planet.

[Jim__]

10. You can read it any way you want. Hawking explicitly states ...

... ... one can use either picture as a model of the universe.

[Greyskye]

15. You really shouldn't leave off the next sentence:

The real advantage of the Copernican system is that the mathematics is much simpler in the frame of reference in which the sun is at rest.

Occam's Razor, anyone?

[Jim__]

18. See post #4. How many times do I need to add the sentence? - n/t

[Sinistrous]

17. Quiz score: Zero.

My guess that you would dodge that question was sadly correct.

[Jim__]

19. What's sad is your inability to grasp the implications of a change of model.

Under the Ptolemaic System, a system that Hawking tells us is valid, a star that orbits a planet is the sun. Is that really beyond your grasp? Do you really need that to be explicitly stated?

[Sinistrous]

21. What is sad is your ability to name one OBSERVED sun obiting a planet.

All the sophistry you can muster does not negate the fact that ALL observations prove the accuracy of the Copernican model and utterly destroy any validity of the Ptolemaic system. Hawking was playing mind games and you lost.

[Jim__]

22. "Hawking was playing mind games ..."

And yourevidence that Hawking was "playing mind games"?

No. Hawking was stating a fact about the nature of our knowledge of the cosmos. The point you seem incapable of grasping is that the same observations that support Copernican model also support the Ptolemaic model. That's the point Hawking was making.

[Sinistrous]

23. "Support the Ptoemaic model" ????

Then it should be easy for you to point out the countless suns orbiting planets.

If you can't point out any, you lose.

And yes "mind games" since he was talking about views from the unaided perspective of earth. Fortunately, astronomy has allowed us to go beyond that.

[Jim__]

24. Do you have any evidence to support your contentions?

Then it should be easy for you to point out the countless suns orbiting planets.

Here is Hawking's description of Ptolemy's system: Ptolemy published his work in a treatise explaining reasons for thinking that the earth is spherical, motionless, positioned at the center of the universe, and negligibly small in comparison to the distance of the heavens.

Explain how you arrive at the conclusion that under that system, you expect to find countless suns orbiting planets.

---

And yes "mind games" since he was talking about views from the unaided perspective of earth.

Please point to Hawking's statement that he is talking about views from the unaided perspective of the earth.

[Sinistrous]

26. Either identify the stars that orbit planets, or

crawl back under your rock.

P.S. If you think that I have concluded that there are "countless suns orbiting planets", you cannot read well enough to interpret Hawking. Since the Ptolemaic model has been utterly debunked, I don't use it to predict or to conclude anything. But since you think that it has something to offer, where are the other stars orbiting planets, as would be the case under you precious (and ludicrous) Ptolemaic model?

[Jim__]

30. As I expected, no evidence for your claims.

If you think that I have concluded that there are "countless suns orbiting planets", you cannot read well enough to interpret Hawking.

From the previous posts in this thread:

From your post #23:
"Support the Ptoemaic model" <sic> ????
Then it should be easy for you to point out the countless suns orbiting planets.

From my post #24:
Then it should be easy for you to point out the countless suns orbiting planets.

Here is Hawking's description of Ptolemy's system: Ptolemy published his work in a treatise explaining reasons for thinking that the earth is spherical, motionless, positioned at the center of the universe, and negligibly small in comparison to the distance of the heavens.

Explain how you arrive at the conclusion that under that system, you expect to find countless suns orbiting planets.

Your post #26:
If you think that I have concluded that there are "countless suns orbiting planets", you cannot read well enough to interpret Hawking.

Since the Ptolemaic model has been utterly debunked, I don't use it to predict or to conclude anything. But since you think that it has something to offer, ...

Once again, all this statement shows is your inability to grasp what Hawking is saying. He is not claiming that the Ptolemaic System hase something to offer. To the contrary he states: The real advantage of the Copernican system is that the mathematics is much simpler in the frame of reference in which the sun is at rest. He explicitly acknowledges the advantages of the Copernican system. As has been stated previously - posts 6 and 22 - Hawking is making a statment about the nature of our knowledge.

Either identify the stars that orbit planets ...

The Ptolemaic System makes no such prediction - using "planet" as it is used in the Ptolemaic system.

... or crawl back under your rock.

Your inability to discuss issues at an adult level fits well with your complete lack of understanding of the issue Hawking is raising. Your childishness renders further discussion pointless.

[Sinistrous]

33. As expected, you cannot defend your support of your foolish position.

Ptolemy was describing the motion of stars and planets. Even granting Hawking's surmise that we cannot tell if the earth's star orbits earth or vice versa, if Ptolemy's rule is valid, there must be other star-orbiting-planet systems in the universe. There aren't, of course, which is why you so coyly avoid the challenge to identify one. To say that "The Ptolemaic system makes no such prediction" is rank sophistry.

[muriel_volestrangler]

36. Ptolemy would not regard the sun as a star

You're trying to get too much out of that system. When you say "if Ptolemy's rule is valid, there must be other star-orbiting-planet systems in the universe", that's going far too far. You can't even say "if Copernicus's system is valid, there must be other planet-orbiting-star systems in the universe" - the laws of motion from Copernicus, Kepler and Newton do not insist there are any other planetary systems at all. But Ptolemy never tried to make predictions about things that hadn't been observed yet.

Hawking is, I think, taking a mathematical point to extremes. You could write equations that end up saying the earth is stationary, but for all other bodies, they'd contain components that look exactly like the motion of the earth as we work it out, but with the reverse sign. This would end up being insanely complicated, and there would be no underlying explanation of why the equations are like that; whereas the laws we use have a simple explanation of inertia, an inverse square law for gravity, and so on, and have made predictions that have then turned out correct. Under a Ptolemaic system, people would be stuck with observing the motion of celestial bodies, and saying they can't say why they move as they do. And motion of bodies here on earth might be left without a decent explanation as well - if these nutters claim the earth doesn't rotate either, they'd not have an explanation for the Coriolis effect either.

It's the equivalent of an extreme solipsistic philosophical viewpoint - you could say you're not sure any other person actually exists, and so you'll call them products of your own imagination. Then you'd describe everything like "I imagine that the being which I imagine is to my right throws what I imagine is a ball which I imagine changes what I call 'position' in this way, which I imagine is due to a force between objects I have called 'gravity ..."

[Sinistrous]

39. good grief.

More twaddle digging the grave of Ptolemy's naive fabrication.

You bore me. Good bye.

Enjoy "the last word" in your inevitable next post.

[muriel_volestrangler]

40. That's not a productive way to post; you are making this personal

OK, I'll use my 'last word' to criticise your attitude, since you have not attempted to say anything to me on the topic of this thread.

Your phrasing it, itself, a petulant way of behaving; you imply that I 'enjoy' making my posts as if that is a problem. You therefore imply that your posts are serious and high-minded, while others (and you were replying to my first post in this thread, so you are not judging from just a pattern of my posts) were simply frivolous. Yes, I do enjoy posting on DU, in general (it's voluntary, after all, and I wouldn't do it if I didn't enjoy it, and the same goes for you), but I do it in the hope of a productive conversation from which we all might learn. If your approach is to not attempt to address my points, but to make it personal with "you bore me", you just ruin the atmosphere of DU. Your pre-emptive "your inevitable next post" is a passive aggressive attempt to get 'the last word' for yourself. There's nothing surprising about people replying to posts; stop trying to make yourself out as a martyr who is being annoyed by people you regard as beneath you.

Shape up. That's no way to post at DU.

[Sinistrous]

44. Dear Muriel,

I apologize for addressing you as I did. Frankly, I didn't check your name and assumed that any post in that series was from the sorry lad I had been arguing with, not realizing he had left the field.

So take my comment above in that light and bind up your wounded sense of propriety.

[SkyDaddy7]

29. I think had you expanded on the "Goldfish Perspective"

covered in the book it would have helped...Plus, doesn't Hawking & Mlodinow go into how to overcome this potential observational flaw when it comes to constructing a view of the cosmos? I think they do because it would be hard to argue what he is arguing in the book if not.

I need to read the book again...I really like Hawking as a person! Respect & admire would probably better describe how I feel about him as a person not as a scientist...Although the same would apply to him as a scientist as well.

[Jim__]

31. Hawking does list "elegance" as one of the qualities of a good model.

His example between the Ptolemaic and Copenican systems clarifies why elegance is an important consideration. It clearly distinguishes the Copernican from the Ptolemaic system - although I believe elegance can only decide between two equivalent systems. But, he also states that there is no theory independent view of reality. The test of a theory is to correctly predict events. For the solar system, the Ptolemaic Theory did that. The interesting question to me is, if we had stayed with the Ptolemaic System, could it have made accurate predictions about the larger universe? If it could, our "laws" would be very different, but they would work. But the computational advantages of the Copernican System are enourmous and the math required in the Ptolemaic System may not have been possible.

[SkyDaddy7]

34. I liked the Goldfish analogy!

I can't help but think about that as I read about how we view our universe! We are staring out of our fish bowl!

[Jim__]

35. I agree - it really clarifies what he is saying - n/t.

[xocet]

9. Galileo was Wrong: A Conference Espousing an Essential Ignorance of Modern Physics

Geocentrism - as given above - defines both an absolute coordinate system and an absolute state of motion and associates both of them with the earth. (It is unclear that geocentrists even appreciate that motion is relative.) Special relativity describes the world in terms of relative motion (velocity) and relative position. Without the corrections that special relativity makes understandable, non-spacetime GPS data would not be accurate.

Therefore, there is no real implication in your noted excerpt from the book,The Grand Design, that the Ptolemaic model is equally valid with Einstein's theory of special relativity or with his general theory of relativity both of which reflect a more modern state of knowledge - the Copernican model aided the advance of astronomy and the advance of physics, so it belongs to the ancestry of Einstein's models. Dr. Hawking is well-aware of Einstein's work. He and his co-author seem only to be putting forth the point that no model completely encompasses all 'reality' and - on that basis - (the basis that the models are all incomplete) the models are in a sense equivalent.

Please keep in mind that you are reading a description of models that are both pre-Newton and pre-Einstein and that Dr. Hawking's and Dr. Mlodinow's book is a popular science account. They are both fully aware of Einstein's work, but the detail needed to cycle through the theories from Aristarchus to Einstein would likely kill the popular appeal of the book.

In your post, you state:

They're not actually proclaiming that the earth is flat, but rather that it's motionless: Geocentrists accept a spherical earth but deny that the sun is the center of the solar system or that the earth moves

The essential point is that whether one claims that "the earth is flat" or that the earth is "motionless", one is equally mired in pre-relativistic physics. Also, please note that the book's excerpted comment that regards mathematics is strictly limited to the simplification of the computation of classical orbits.

For reference purposes, here is a decent book on special relativity: Spacetime Physics by Taylor and Wheeler.

[Jim__]

11. Please read what is explicitly stated.

... one can use either picture as a model of the universe. So, unless Hawking is wrong on this, either can be used as a model of the universe. I'm quite aware the ideas of modern physics. I hear Hawking is too. My inclination, barring any evidence to the contrary, is to take him at his word on this.

[immoderate]

13. It's a model that accounts for every day experiences.

But the flat earth model works just as well.

--imm

[xocet]

16. So...

You wrote:

Stephen Hawking's new book lends them some support.

They're not actually proclaiming that the earth is flat, but rather that it's motionless: Geocentrists accept a spherical earth but deny that the sun is the center of the solar system or that the earth moves

In Hawking's new book, he says that each is a model and the advantage of the Copernican model is computational convenience:

A famous example of different pictures of reality is the model introduced around A.D. 150 by Ptolemy (ca. 85–ca. 165) to describe the motion of the celestial bodies. Ptolemy published his work in a treatise explaining reasons for thinking that the earth is spherical, motionless, positioned at the center of the universe, and negligibly small in comparison to the distance of the heavens.

This model seemed natural because we don't feel the earth under our feet moving (except in earthquakes or moments of passion). Ptolemy's model of the cosmos was adopted by the Catholic Church and held as official doctrine for fourteen hundred years. It was not until 1543 that an alternative model was put forward by Copernicus. So which is real? Although it is not uncommon for people to say Copernicus proved Ptolemy wrong, that is not true. As in the case of the goldfish, one can use either picture as a model of the universe. The real advantage of the Copernican system is that the mathematics is much simpler in the frame of reference in which the sun is at rest.

• Your subject line claims that a noted authority's book supports a vaguely-defined group's vaguely-defined belief system which is referenced in the OP.
  
  
• Then you provide specific statements and by the presence of those statements imply that these beliefs are validated by the noted authority's book.
  
  
• Then you provide an excerpt of the noted authority's book and, thus, implicitly claim that excerpt provides the aforementioned support to said group and belief system.
  

Basically, what you write is only minimally true. If you want to talk about ontology or even the existence of models, that is great, but all Dr. Hawking is saying is that there are different models of the universe. All models are not equally valid, and he is not speaking to the modern validity of the Ptolemaic model. In your post, it is your characterization of that statement that is dishonest by its implications: to wit, Dr. Hawking would likely equally well support the claim that my cat is model of the universe, but that does not mean that he accepts my cat to be a good model of the universe.

[Jim__]

20. First, try to get your facts straight.

Your subject line claims that a noted authority's book supports a vaguely-defined group's vaguely-defined belief system which is referenced in the OP.

No, my subject line claims that Hawking's book lends them some support, which is exactly what it does. Hawking's book explicitly states that the model this group is claiming is true is a valid model.

all Dr. Hawking is saying is that there are different models of the universe. All models are not equally valid, and he is not speaking to the modern validity of the Ptolemaic model.

What is your basis for the claim that Hawking is not speaking to the modern validity of the Ptolemaic model? From his book: So which is real? Although it is not uncommon for people to say Copernicus proved Ptolemy wrong, that is not true. As in the case of the goldfish, one can use either picture as a model of the universe. The real advantage of the Copernican system is that the mathematics is much simpler in the frame of reference in which the sun is at rest.

---

In your post, it is your characterization of that statement that is dishonest by its implications: to wit, Dr. Hawking would likely equally well support the claim that my cat is model of the universe

That is just an invalid inference that you're drawing. But, that's what you need to claim that my post is dishonest. My original post on this is essentially an excerpt from Hawking's book. That you draw invalid inferences from it is not really my problem.

[muriel_volestrangler]

37. No, Hawking does not "explicitly state the model this group is claiming is true is a valid model"

He says a Ptolemaic (ie geocentric) model could be valid, but he does not explicitly say this particular one from these nutters is. The last Ptolemaic model that any serious observer put forward would not be valid, because it wouldn't describe in sufficient detail later observations that have been made, eg the apparent motion of stars due to parallax, or the anomalies in Mercury's orbit that weren't explained until general relativity was taken into account.

I'm willing to bet these bozos have not come up with a model that mentions observed details like that - I think it would challenge anyone to give a coherent explanation with their starting point of the earth not moving. It could, theoretically, be done - just as, in theory, you can solve simultaneous equations that involve 78 variable in your head, but no-one has ever done so.

[Lyric]

25. I get what Hawking is saying, but he's talking about frame of reference

which is not the same thing as physical reality, obviously. A frame of reference argument is that, since all cosmic bodies are suspended in space and are in motion, there is no one place that is "grounded" (motionless) to use as a point of reference when deciding which bodies are "orbiting" and which are BEING orbited around. He's trying to explain why both points are view are valid from a relative POV perspective--and if gravity wasn't a factor, the Ptolemaic system could easily be true.

However, we have more than just visual points of reference. We know much more about gravity now, and that knowledge is testable. We know that objects that have greater mass also have greater gravitational "pull", so smaller bodies tend to orbit around larger bodies. The Earth doesn't have enough mass to be center of the solar system, much less the universe. But there IS another body in our solar system that DOES have enough mass to exert that kind of gravitational pull--the Sun. Only the Sun is large enough, dense enough, and massive enough to have the gravity needed to keep all of the planets orbiting in the paths they're currently in. From a physics standpoint, it's simply not possible for the Earth to be the "hub" of the solar system. It just isn't big enough.

[Jim__]

32. Hawking also says that there is no theory independent view of reality.

Our view of reality depends on our theory.

So, if we stayed with the Ptolemaic system, we would need something like gravity, but it would have to work differently than our current ideas about gravity. I don't know if the Ptolemaic system could come up with sufficient laws to support a frame of reference that held that the earth is immobile and the center of the universe. That, to me, is the most interesting question that Hawking's statement raised.

And gravity, of course, is still not completely understood; and there are incompatibilities between General Relativity and Quantum Theory. My understnding is that these incompatibilities can be overcome through M-theory. Hawking accepts M-theory in this book. M-theory, of course, has not been tested. But, given that it makes correct predictions about known events - we haven't been able to test predicted events - is that sufficient to make it a valid model? I'm reading Hawking to say that it is; yet it is subject to invalidation under testing - I think the LHC can test some predictions of M-theory. At least the LHC can test some predictions of super-gravity and super-symmetry which Hawking also accepts in this book.

[caraher]

41. Hawking is trying to correct an erroneous historical oversimplification

There is no chance that Hawking would agree that a geocentric model is inferior to today's heliocentric model solely because of mathematical convenience. His real point is that given the data available a few centuries ago, there was nothing that could not be accounted for mathematically by a geocentric model, and the reasons it fell from favor *at the time* were related more to the superior elegance - which can be framed in terms of mathematical and geometric simplicity - of a heliocentric model that also describes the same data.

But the situation is VERY different in the 21st century. We have data available to neither Copernicus nor Ptolemy. We have sent space probes to other planets, and those space missions conclusively prove that the geocentric model is untenable. Heliocentric and geocentric models, together with the laws of gravitation, give very different answers to the question of how to launch space probe A to reach planet B, and the heliocentric model gives the correct answers while the geocentric model gives wrong answers.

And actually, while what Hawking says was true up to the time of Newton, once Newton formulated his law of gravitation - which beautifully explained Kepler's laws of planetary motion within the heliocentric model - maintaining the geocentric model became much more complicated that coming up with ever-more-intricate sets of epicycles. Before Newton, the argument was strictly geometric. After Newton, one model came with a dynamical explanation of the geometry, while the other required one to rely on some unobserved mechanism to maintain the intricate dance of the planets. Newton's dynamics plus gravity account nicely for the orbit of the Moon around Earth under either model; but when you look at every other body in the solar system, only the heliocentric models work. So maintaining a geocentric model entails rejecting the combination of Newtonian dynamics and Newtonian gravity for every body in the solar system apart from the Earth-Moon system. One can certainly do that in a mathematically consistent way; but the cost of doing so is immensely greater than it was when nobody could account for planetary motions in other than strictly geometric terms.

[Jim__]

42. You're denying what Hawking explicitly states.

You state: There is no chance that Hawking would agree that a geocentric model is inferior to today's heliocentric model solely because of mathematical convenience.

Hawking states: The real advantage of the Copernican system is that the mathematics is much simpler in the frame of reference in which the sun is at rest.

Further, to assume that Hawking is only talking about the past is to assume that either he cannot speak English very well, or he is deliberately misleading his readers. Hawking is speaking in the present tense:

So which is real? Although it is not uncommon for people to say Copernicus proved Ptolemy wrong, that is not true. As in the case of the goldfish, one can use either picture as a model of the universe. The real advantage of the Copernican system is that the mathematics is much simpler in the frame of reference in which the sun is at rest.

As to all that we've learned since, we've learned that based upon looking at the universe from a Copernican perspective. That, I believe, is the precise point that Hawking is making. The Ptolemaic system would have led to a very different view of the universe than the one we have now. But, if it could be used to make accurate predictions, it would be a valid model, and we would probably naively accept it as an accurate physical description.

Hawking states, immediately after these paragraphs that there is no picture- or theory-independent concept of reality:

These examples bring us to a conclusion: There is no picture- or theory-independent concept of reality. Instead we adopt a view that we call model-dependent realism: the idea that a physical theory or world picture is a model (generally of a mathematical nature) and a set of rules that connect the elements of the model to observations. This provides a framework with which to interpret modern science.

Though realism may be a tempting viewpoint, what we know about modern physics makes it a difficult one to defend. For example, according to the principles of quantum physics, which is an accurate description of nature, a particle has neither a definite position nor a definite velocity unless and until those quantities are measured by an observer. In fact, in some cases individual objects don't even have an independent existence but rather exist only as part of an ensemble of many.

We view the world through the prism of our model and what we see, in large part, depends upon that model. Do I think that our current picture of the solar system is accurate? Sure. But, I see Hawking making a much more important point than that.

[caraher]

45. I think you're right on the broader point Hawking is making here

I'm completely confident, though, that Hawking would agree with me that what he says about the advantages of the Copernican model over the Ptolemaic system is true only relative to the data available in the time of Copernicus and shortly thereafter. Both models are equally adequate to account for the relative locations in the sky of all the planets *as seen from Earth*. But they give incompatible predictions for many other things we can measure. One very obvious example is that the distance between Earth and, say, Mars is approximately constant in the geocentric model; the variation in distance is basically approximately the size of the largest epicycle. In the heliocentric model, by contrast, Mars can be as far away as the Earth-Sun distance plus the Sun-Mars distance, and as close as the difference between the Sun-Mars and Sun-Earth distances. This is a much larger variation than is possible in a Ptolemaic model, and we can measure the actual distances in ways that do not depend at all on which model we choose. (For instance, given that we have probe on Mars and we know the speed of radio signals, we find that the propagation delays match the heliocentric geometry and do not match what one might predict from *any* possible Ptolemaic models.)

More available data provides extra constraints on viable theories. Simplistic texts suggest that Copernican models overthrew Ptolemy based on the same data, but originally the both accounted for the same data. But our choices of viable models are much more severely constrained by a vast wealth of additional observational evidence, obtained by a huge array of different techniques that go beyond the naked eye astronomy that gave birth to both original models. Maintaining a geocentric model is incompatible with a much larger body of scientific knowledge today than in the time of Galileo; for instance, you'd have to reject the present understanding of radio wave propagation to hold the geocentric theory against the observational evidence I mentioned above.) One you agree that we can measure distances from Earth to planets - which was not possible with naked-eye astronomy - the trajectories of planets in the solar system graduate from theoretical constructs that explain naked-eye observations of motion relative to the "fixed stars" to experimental results subject to no more theoretical ambiguity than whatever scientific assumptions go into the distance measurements themselves.

[thereismore]

12. I have nothing to say. nt

[kenfrequed]

14. I'm stunned.

Simply stunned.

[tomm2thumbs]

27. akin to a reproductive scientist debating someone defending 'the stork theory'

[The Wizard]

28. Is this from

http://landoverbaptist.org/ ?

[AsahinaKimi]

38. Flat Earthers just need

A sea cruise. They will be told that anyone who sees and documents the Oceans dropping off into outer space will be given ten thousand dollars.

[Radical Activist]

43. They're meeting in conjunction with the climate change skeptics.