Wednesday, January 7, 2009

Judaism and Geocentrism

I’ve blogged before about geocentrism as a modern phenomenon. Geocentrism, the belief that the Earth is at the center of the universe, was a center piece of the Ptolemaic system and was overthrown by the work of Copernicus, Kepler and Galileo. However, certain extremist religious groups have continued to insist on geocentricity and have claimed to have scientific bases for their beliefs. Until recently, I believed that the modern geocentrist movement existed only in certain extreme Christian groups especially Protestants.1 This view is in error. There are ultra-Orthodox Jews who are geocentrist.

Most of the active Jewish geocentrists are Lubavitchers. In contrast to the Christian geocentrists who have as their main impetus for geocentrism various Biblical verses, 2 the Jewish geocentrists seem to in a large part be motivated to preserve the correctness of certain statements by Maimonides. In particular, they defend the cosmology as set out by the Maimonides in the Mishne Torah. I am puzzled by these apologetics for two reasons: First, there does not appear to be any similar attempt to defend incorrect medical statements by Maimonides. Second, there’s no theological need even among charedim to believe that Maimonides was infallible. Prior to this, I have seen attempts to argue for what amount to infallibility of the Talmudic authors but had not previously encountered such attempts where later authors such as Maimonides were concerned.3

Like the Christian geocentrists, the Jewish geocentrists prefer two lines of argument which are contradictory and yet are used in tandem. First, they argue that under General Relativity one can always construct a coordinate system with a given point as stationary so one might as well assume that the Earth is at the center.4 This argument has been sometimes called “weak geocentrism.

The second argument, “strong geocentrism,” is the claim that the Earth is at the center of the universe in a meaningful fashion; that is, there are lines of evidence which only make sense if the Earth is at the center of the universe. How both these claims can be made simultaneously is not clear to me. Apparently, studying Talmud on a daily basis does not help ones logical skills as much as one might hope. As with the Christian geocentrists, the Jewish geocentrists have a strong anti-science bent; they either insinuate or state outright that there exists a massive conspiracy within the scientific establishment to discredit geocentrism. Like their Christian counterparts, the Jewish geocentrists credit the Copernican system with inspiring later heresy such as evolution.

On the whole, the Jewish geocentrists in thoughts and arguments are very similar to the Christian geocentrists. As with the Jewish and Christian anti-evolutionists it is not obvious to me whether there is cross-fertilization or independent arrival at the same ideas. I suspect there is cross-fertilization but the mechanism is unclear. More research is needed.
While Catholic geocentrists also exist they are rarer than their Protestant counterparts. Geocentrism is in fact not the most extreme extant cosmological belief; there are a handful of extant flat-earthers especially among Islamic groups. See for example this video of a debate on Iraqi television about whether the Earth is flat.
2. Such as Joshua 10 in which the sun stands still.
3. Orthodox apologists use a variety of different arguments to defend against apparent errors of fact in the Talmud. One of the more transparent attempts is to claim that the nature of the universe has changed since the Talmudic time. This claim shows up in a variety of different forms including explaining the Talmud’s apparent confusion about the human female menstrual cycle. My impression is that many such claims are pro forma; I have yet to find anyone who was been willing to state explicitly that they think the basics of human anatomy have changed in the last 2000 years.
4. I’m not sure this is in fact strictly true. I’d appreciate input on this subject from people who understand general relativity. In fact, this weak geocentrism is not sufficient to save Maimonides's cosmology since he has the various planets in circular orbits about the Earth and has the sun in a circular orbit about the earth (along with a few epicycles). This contradicts observed data even if the Earth were stationary.


Golis said...

Regarding note (iv), weak geocentrism is the general relativistic version of a physicist trying to get out of a speeding ticket by explaining that, from his reference frame, he was stationary and the Earth was moving.

When Einstein was developing general relativity, his guiding thought experiment was about a man in a box, who would be unable to tell what portion of the acceleration he saw was due to gravity and what was due to a force on the box. Einstein wanted (and produced) an equation which gave equal authority to the man in the box and the man outside of it, who can witness the objects pushing the box. This idea was an extension of his thought experiment that motivated special relativity, giving equal authority to a man on a train and a man watching the train go by.

Imagine that the walls of the box are transparent. Imagine further that the box is in free fall toward the sun, according to the man outside the box. The man inside the box will feel no gravity, just see the sun barreling toward him.

Being in orbit around the sun is simply a matter of being in free fall around the sun with an angular velocity sufficient to miss it. A person on Earth, in orbit around the sun, is in exactly the same situation as a man in that box.

Of course, one could just as easily construct a coordinate system in which Mercury, Venus, Mars, etc. were stationary. Personally, I am a Joviocentric.

Joshua said...

Golis, that's all correct for a non-accelerating reference frame. I don't know if that's precisely true for accelerating reference frames. In particular, since the standard reference frame the Earth is accelerating I don't know if there is a valid reference frame that has the Earth as stationary.

Moreover, assume the Earth is stationary. Then objects that are at the outskirts of the solar system need to be moving faster than the speed of light. (A back of the envelope calculation shows that already by Uranus or so one is going faster than lightspeed). That doesn't seem to be quite right. But my understanding of GR is poor so it is possible I'm missing something. I've asked a few physics people for input.

Benjamin Fischer said...

It's extremely surprising to me that Lubavitchers are trying to preserve Maimonides's geocentric astronomy, given that Maimonides himself expressed grave doubts of the validity of Ptolemy's astronomy in his "Guide to the Perplexed."

Joshua said...


That's an excellent point. Thanks for pointing that out. I had forgotten how much discussion of astronomy there is in the guide. There's substantial criticism of the Ptolemaic system as laid out in the Almagest especially in regard to the idea of epicycles. In that context, it seems like the work in the Mishneh Torah is arguably meant to be more a statement about the halachic procedure for calcuation since in the Guide he agrees that much of the Almagest's methods give accurate calcuations. On the other hand, this would not be the only example of Rambam contradicting himself in different books or of him apparently changing his position over time.

You've made an excellent point that makes this behavior even more puzzling.

Anonymous said...

I can shed some light on this. Lubavitchers claim to be defending the Rambam, and may be taught to believe this, but actually they are defending the Lubavitcher Rebbe, who wrote a letter on this topic in which he argued that the theory of relativity proves that it is impossible to say whether the sun revolves around the earth or vice versa. He seems to not understand that relativity only applies to objects moving with constant speed and direction, not to circular motion. In any case, he wrote the letter and it is even reprinted in the popular English/Hebrew lubavitch chumash. This makes it true, from their perspective, and they argue that any Jew who does not believe this is contradicting Rambam.

sniffnoy said...

This post also has broken anchors.

Strangelove said...

More info on our geocentric universe here: