...and now it's the geocentrists, who want to return to the days of Ptolemy:

Mention geocentrism and physicist Lawrence Krauss sighs. He is director of the Center for Education and Research in Cosmology and Astrophysics at Case Western Reserve University and author of several books including "Fear of Physics: A Guide for the Perplexed."

"What works? Science works. Geocentrism doesn't. End of story," Krauss said from Cleveland. "I've learned over time that it's hard to convince people who believe otherwise, independent of evidence."

To Sungenis, of Greencastle, Pa., evidence is the rub.

For several years the Web site of his Catholic Apologetics International (www.catholicintl.com) offered a $1,000 reward to anyone who could disprove geocentrism and prove heliocentrism (a sun-centered solar system).

There were numerous attempts, Sungenis said, "some serious, some caustic," but no one did it to his satisfaction. "Most admitted it can't be proven."

There's also no proof that the Earth rotates, he said.

But what about Foucault's famous pendulum? Its plane of oscillation revolves every 24 hours, showing the rotation of the planet. If the Earth didn't rotate, it wouldn't oscillate.

Nope, Sungenis said: There just may be some other force propelling it, such as the pull of stars.

These loons are like the "NASA faked the moon landings" type. They're impervious to facts, evidence or logic. But everyone can look down on someone:

Sungenis wants to make sure "people don't classify geocentrists with Flat Earthers. We don't believe that at all."

Oh, well, that's all right then.

[Late afternoon update]

One of Jonah's emailers had a (sort of, well not really) defense of geocentrism:

It is not my intent to defend geocentrism, but I do weary of the common rebuttal that "the earth goes around the sun." Imagine, if you will, if the earth and sun were the only two bodies in the solar system. How would one make the case that the earth went around the sun and not vice versa? And is it not curious that no one argues that the moon goes around the sun, although technically, it does? The problem is not who revolves around whom, but what frame of reference yields the simplest description of motion. Copernicus did not overthrow geocentrism so much as he provided a different reference point that made it possible to describe planetary motions as ellipses rather than epicycles and other wierd paths.

Well, no, even that doesn't help.

The problem with geocentrism isn't that it merely claims that the sun goes around the earth. It's true, as Jonah's emailer writes, that both earth and sun revolve around each other (though the sun barely budges in its tiny orbit around their common center of gravity, which is contained entirely within itself, and superimposed with the motion resulting from its interactions with all of the other planets).

The geocentrists' problem is that they believe that the sun going around the earth explains the daily cycle of light and dark. But the sun and earth revolve around each other once a year, not once a day. They are essentially denying the very fact of the earth's rotation in inertial space. Note that their explanation also makes it much more complicated to explain seasons, since they've essentially denied the natural motion that causes things to go through an annual cycle (that is, the sun can't go around the earth both once a day, and once a year).

Sungenis is a nut whose been blacklisted by most of the Catholic community. All he's good for is making Catholics cringe whenever his name is brought up.

http://www.spaceref.com/news/viewpr.html?pid=17712

Part of the problem is the notion of "proving something". Only in math can you prove anything. The rest of the scientific community is dependent on observation and experiment. You cannot, literally, prove anything that way. According to Karl Pooper, the best one can hope to do is disprove the validity of something through observation and experiment.

When confronted with someone spouting such a challenge as "prove it", I always start with a question: what would it take to make you believe that you are wrong? If, for example, a person were to say that the Sun orbits the Earth, and I claim otherwise, and he asks me to prove it, I would question what would make him believe that the Sun does not orbit the Earth. Then I would either state that that is beyond the ability of the scientific process to provide, or would provide the evidence. But usually it does not get to that point: a person who argues this way generally responds with "nothing". At which point, there's no point in a discussion.

What does one have to do to "prove" that the earth goes around the sun?

Orbital mechanics clearly don't work the other way around--see epicycles. I would have thought that mathematics and astronomy "proved" rather well how the solar system is ordered, and if we were wrong, our probes wouldn't go where we expect.

I never understood the religious justification for geocentrism, either. Humanity is God's creation, and therefore the heavens must literally revolve around it? That just doesn't make sense to me--but then, I don't have any problem with the whole 7 days/15 billion years thing, either.

I suppose that one could make the argument that the earth is the center of the universe and that everything revolves around it. I have no doubt that you can gin up a perfectly valid mathmatical description to explain that point of view, even to the point where you could put a lander at a selected spot on Mars.

So what?

They tried that. Hence, epicycles.

Things just don't move in the night sky as they should if everything revolves around the earth. The math doesn't work.

The math works amazingly well if you assume that the earth is going around the sun.

As Rand points out, the matter of rotation is an even more stark contrast, one that I was forgetting. If you assume that not only the earth does not revolve around the sun, but that it does not rotate either, then the phases of the moon or other planets make absolutely no sense at all.

True.

I did not say it that such a description would pretty, just that it could be done.

That is why heliocentricity is generally the accepted (better?) explaination. The simplist explaination is most probably true.

Ocams's Razor.

I'd call it "parsimony" rather than Occam's razor. You effectively have multiple mostly correct explanations of celestial mechanics. After all, we can continue to add epicycles or translate everything into terms of geocentral coordinates (ie, some system of coordinates that uses the Earth as a fixed, central reference point) and get a model that works to our desired precision. But the information required to describe these other models is significantly greater than that required for Newtonian mechanics or general relativity.

Further, these models don't extend very well. If we wish to model rotating neutron stars in another galaxy, it's pointless to shift everything to a geocentral coordinate system. But it can be done by the hopelessly pendantic.

"Things just don't move in the night sky as they should if everything revolves around the earth. The math doesn't work."

Well, theoretically you COULD get the math to work (taking into account that an earth-based frame is non-inertial). But it would be hideously complicated, with hundreds of rotational terms, frame force terms, time dependent orientation terms, and all sorts of nonsense that just goes away if you look at it from an inertial perspective. So why bother?

The only reason I can think of is that some people want to put the anthropocentric notion that the ancients had about the structure of the universe on an untouchable pedestal. Truth being re-defined as whatever happens to be in their religious book instead of whatever happens to be the state of the world, they can proceed to use literalism as the sole justification for their worldview (and "enlighten" the rest of us benighted sinners with it).

I'm a Joshiocentrist.

I can prove irrefutably that the sun goes around the Earth. Ladies and gentlemen of the jury, this is Chewbacca. Chewbacca is a Wookie...

I would think that parallax, the fact that stars seem to change their position due to Earth's motion around the sun throughout the year, would be a pretty convincing argument. If the Earth were going around the sun, then there'd have to be a very concerted, complex motion of all the other stars to explain it.

As someone said, however, no amount of this information will change some peoples' minds.

Start with F=G*m1*m2/r^2 once that is accepted then the rest follows.

Of course if the proponents are ignorant of math then there is no hope.

Doesn't general relativity hold that any inertial frame of reference works (in principle) as well as any other, including a rotating frame of reference? In other words, sure, you can hold that the Earth stands still and the universe rotates around it, and the twisting of space (or whatever) caused by all those stars and planets zipping around us would cause the Foucault pendulum's precession, the Earth's equatorial bulge, and so forth.

The real answer to geocentrism, post-Einstein, is not "You're wrong," but "So what?" ANYTHING can be considered the stationary center of the universe. Big whoop.

Doesn't general relativity hold that any inertial frame of reference works (in principle) as well as any other, including a rotating frame of reference?

Rotating frames of reference are not inertial.