In response to a reader's inquiry:  

R Dovid Ganz was of the opinion of a helioCentric universe (see his Sefer  מגן דוד 

In his sefer נחמד ונעים he speaks of a different celestial issue, regarding what moves, the "spheres" or the stars, and relates to a well-known difference between the opinions of science and of the Rabbis, but today of course we know that there are no such "spheres" in any case, and we will not depve into this specific topic here.

"אך תדע שהחוקר הגדול המופלא בחכמת הכוכבים ויחיד בדורו... השר טיח"א בראה"י אמר לי: לא יפה עשו חכמיכם שהודו לחכמי האומות על דבר שקר, כי הדין היה עם חכמי ישראל. באומרו שהכוכבים חוזרים במהלכם העצמיים בלתי הכרח תנועות הגלגלים, רק בעצמם שטים ורצים כעוף הפורח באוויר, והרבה בראיות... וכן שמעתי מפי החכם המופלג קעפלירו"ס."

— נחמד ונעים, שער א סימן כ"ה

In the article above I am dealing with geocentrism vs heliocentrism, not specifically whether this or that person believed the stars are "free of the spheres" or not; the point I made was not that R Gans agreed or disagreed with Rabbinic statements and scientific statements aobut other issues but specifically that he was NOT a geocentrist - like Galileo Tycho etc he was a heliocentrist, which was the novel scientific view of the universe (until much later when it was realized that the universe is so much larger than our solar system plus a bunch of stars centered about it, and that the sun too is not "the center" of the universe).  

...

A reader asked: I read through you articles, this isn't really my field but perhaps you can enlighten me.

You seem to mention how general relativity allows for one state "the the sun rotates about the earth"

Is such a statement valid with Newton law of gravity?

My reply: Newtonian gravity is obtained as a limit of General Relativity - ie in very special cases, for specific conditions, the field equation and equaitons of motion of Einstein's theory of general relativity reduce to the much simpler ones of Newtonian gravity. Therefore, if something is valid in GR it is obviously definitely valid for Newtonian theory, but not v.v.

There's no question of course that in ordinary parlance "the Earth spins, and it orbits the sun". The article analyzed however whether the language of the Torah implied differently, or intended for us to believe differently (I don't think it does), and whether even if it did imply 'geocentrism', whether that meant the Torah was flawed (I don't think it would imply this, for various reasons, including the ones specified in the article).

BTW: If you have a deep interest in Newtonian gravity and general relativity, I highly recommend watching my lectures on these topics, as indicated here.

..

A reader wrote: You are demonstrating that the Ptolemy and the Newtonian systems are not provable. I followed all your arguments. But, let me ask why we cannot disprove the model of the ancients by factoring in the observations of the astronauts who saw a spinning earth on the way to the moon. They  traveled in a straight line as expected by the laws of physics (once they left the earth's gravitational field) as predicted by Newton's first law. Without that law the fuel needed would not have lasted the two week flight. Some have suggested to justify Ptolmey that they traveled in elliptic patterns around the earth each revolution spiraling away. This would be an amazing feat to keep it in a straight line as they got back to the same point. Of course, the accelerators would have to detect a change of angle and yet they didn't do so. Of course, maybe instruments measure only what you set them to do.  (I worked on Apollo). 

  The Rambam at the end of chapter two also adds the Aristotelian idea of the 4 elements between the  earth and the moon. Kabalah talks about these being spiritual however the Rambam is talking about physical things.THe same astronauts did not encounter fire and water along the wrong. Just pure empty space with maybe a dust particle here and there. Nothing to effect the gravity.

   As everyone says you cannot prove things but you can disprove them. I think we have such a situation. I am not saying that Newton is correct only that the other model is wrong, Perhaps there is a third that is true.

...

  The voyager flew at some point above the ecliptic. Is that not a place that the question of geocentric or not can be resolved? They flew perpendicular to teh elliptic? I am going to explore what they discovered. .

...

I don't believe the sun goes around the Earth, nor that the Torah teaches this. 

My article was written for orthodox Jews, to make the point that though some tried to discredit the Torah by claiming (I believe erroneously) that the Torah claims the sun revolves about the Earth, and they stated that science proves otherwise; the article was meant simply to demonstrate why the issue of which ges about the other is not even a scientific question, since Einstein showed that all motion is relative and any reference frame is equally legitimate.

The sun is spinning and rotating about the center of the galaxy and galaxy is moving very quickly etc, and standing on some spinning star in a distant galaxy one might see Earth's motion in one way, standing on the sun another way, standing on the Earth a third way, all are legitimate, physics does not espouse or enfranchise one "correct" way or frame..

And so there is nothing incorrect when we say "the sun sets" because it is as seen from a very convenient frame, and not invalid.  It is only invalid if we think of this a scientific statement of objective truth, ie if we think that it is a fact that the sun sets rather than the earth spins or whatever.

My general reply to several readers

Regarding the question of whether the earth rotates about the sun or v.v:

1) There is no scientific meaning to the question "which REALLY rotates about which" since there is no measureable objective etc means to make such a determination. 

VIP: This does NOT mean that therefore the question is open from the scientific viewpoint; from the scientific viewpoint it is a scientifically MEANINGLESS question.

2) From the scientific point of view there is relative rotation etc between the two and that is all that can meaningfuly be said. 

VIP: A theory which makes a determination as to which "really" moves about which is NOT a more complete scientific theory, it is a MEANINGLESS theory from the scientific viewpoint.

2) Science does not claim to have exclusive TRUTH, it deals only with issues capable of resolution via "objective/scientific" etc means, and so science does not "disallow" one from talking about religious or metaphysical truths, and so for example science/scientists don't think science 'disallows" speaking about "which one "really" rotates about which" as long as one is not claiming to be speaking from a scientific viewpoint, but rather one is aware that they are presenting metaphysical etc beliefs.

3)All the following statements are FALSE (not only from the scientific viewpoint): 

"science teaches that the earth rotates about the sun",

"science teaches (or the theory of relativity shows) that the sun rotates about the earth"; 

"science cannot determine which one is really - in the scientific sense - rotating about which"; 

"science has proven that the earth does NOT rotate about the sun"; 

"science has proven that the sun does NOT rotate about the earth";

even the following is false: "it is equally true scientifically to say that the earth rotates about the sun as to say that the sun rotates about the earth".

The true statement from the scinetific perspective is "THEY ARE IN RELATIVE ROTATION", and that's all that can and need be said.

4) "Judaism" does NOT require belief that the sun goes around the earth; outside the chabad community virtually no rosh yeshiva or gadol or philosopher ever deals with this issue - I do not mean this in a disprespectful sense, only in the sense of speaking precisely: it is only Chabad's approach to Jewish beliefs which perhaps has this issue: it would therefore in my opinion be misleading if someone were to present this as a Judaism/science issue, so that readers would believe that this is the view of all Orthodox Jews, and also that if they do not accept the "Copernican argument" then they are in contravention of "Jewish belief".

In my article I may have said that the geocentric and heliocentric

view were equally correct, as per my previous e mail you can see that

now I would not phrase it that way.

The point of the article would be that:

1) it is incorrect to say that "science disproved the geocentric model

in favor of the heliocentric" or even that "science proved that the

geocentric model is incorrect";

2)science does not offer any scientific objection to someone claiming

some religious truth that in some sense the earth is the "center" of

the umiverse.

According to present day scientific assumption/theory/model there is

no particular location in the universe which is special, no place or

object which is stationary in the absolute sense; therefore the only

type of motion which can be meaningfully discussed is the relative

motion between (somewhat nearby)objects.

According to the modern scientific view the Aristotelian system is

INCORRECT (it attributed intelligence to the planets etc to explain

their motion), the Heliocentric and geocentric models are WRONG if

they are meant to imply that there is a unique center to the universe

and/or that there is some part of the universe which is uniquely at

rest (the sun, or the earth, or anything else) so that other things

orbit them while they are stationary.

WHat one sees from a satellite is different from what one sees from

earth or from the sun, or from a merry-go-round while you are standing

on your head and doing somersaults: the pattern that is seen is

different, but they all are due to relative motion. Some reference

frames, for example one located on the sun, are more useful in that

they produce simpler patterns for the relative motions. But the sun is

NOT STATIONARY in an absolute sense and so it is only one of an

infinite amount of valid reference frames from which to describe the

RELATIVE MOTION of the earth and sun.

Let him read the relevant parts of my article, for example the quote

from Reichenbach and the discussion which followed: the later version

of the article is better, I believe it was reprinted with changes in

the Bohr HaTorah reader (?).

>

………

“Science and the modern World” Alfred North Whitehead 1925  Mentor

edition

p182 geocentrism, heliocentrism seem contradictory but relativity

shows both true;

……………………………….

From web: Stanford Encyc: extract, juxtaposed out of context:

Copernican theory. The significant point was not the replacement of

the earth by the sun as the center of all motion in the universe, but

the recognition of both the earth and the sun as merely possible

points of view from which the motions of the celestial bodies may be

described. This implied that the basic task of Ptolemaic astronomy —

to represent the planetary motions by combinations of circular

motions — could take any point to be fixed, and that, as Copernicus

suggested in the opening arguments of “On the revolutions of the

heavenly spheres,” the choice of any particular point required some

justification on other than astronomical grounds.

neither Copernicus' nor Ptolemy's view can be true — though one may be

judged simpler than the other — because both are merely possible

hypothetical interpretations of the same relative motions. This

principle clearly defines (what we would call) a set of reference

frames, differing in their arbitrary choices of a resting point or

origin, but agreeing on the relative positions of bodies at any moment

and their changing relative distances through time.

…………

An analysis of the consequences of Statement 1, that is, of Machian

relativity, can, as Mach himself insisted, be carried out by comparing

the heliocentric and geocentric systems: “The system of the world is

given

once to us, and the Ptolemaic or Copernican view is our

interpretation, but both are equally actual …The motions of the

universe are the same whether we adopt the Ptolemaic or the Copernican

mode of view. Both are indeed equally correct; only the latter is more

simple and more practical. The universe is not

twice given, with an earth at rest and an earth in motion; but only

once, with its relative motions alone determinable” (emphasis in the

original). (Statement 2).15  IIIC. Are both systems equally correct,

equally actual? With his equally correct assertion, was Mach merely

echoing the famous but

unauthorized preface that Osiander added anonymously to Copernicus’ De

Revolutionibus?

18  That was in 1543, but by 1912 the disk of Venus, the satellites of

the planets, the Foucault pendulum, and stellar aberration,

parallaxes, and Doppler shifts had all been observed.

It is a truism that one can describe any phenomenon from any reference

point. An observer on earth would say that an apple falls to the

ground with an acceleration of 9.8 m/s   2

. An apple-bound observer would say that the earth rushes to the apple

with an acceleration of 9.8 m/s  2

. Also, Brehme 19  has shown that one can obtain straightforwardly a

geocentric system from the Copernican system. Yet, the equivalence in

these examples is purely kinematical. However, Mach would insist that

kinematic equivalence is all that counts: kinematics records

observations, that is, facts, and Mach maintained that science should

adhere to “actual facts”20   focusing on how questions, not why

questions.  21  23 But, it turns out, kinematical equivalence is not

always true. As Kant first noted, the irreducible difference between

the

right and left hands argues against a relational theory of space. 24

Observers using a mirror may make different observations. Given parity

non-conservation, this left/right

asymmetry is true even at the microscopic level: neutrinos are left-

handed in this world, right-handed in a mirror, and, in the mirror,

they behave differently from the right-handed neutrinos

(antineutrinos) in this world. There is no indication that Mach

intended a principle of general covariance (GC). Einstein  25 did

indicate that Mach had influenced him in formulating that principle,

but, for Einstein, GC for the laws of physics was an outgrowth of

Lorentz invariance and required that the laws be formulated in tensor

form in a four-dimensional spacetime.

Mach rejected Lorentz invariance and did not attempt to formulate a

generally covariant theory. GC does not support Statement 2. GC holds

that the laws of physics must be formulated in the same tensor form in

all reference frames, but inertial frames can be distinguished from

all others: the laws of SR physics apply in inertial frames and

observers can determine whether they are in such a frame. In the

falling apple case, an

earth-bound observer would determine that, with gravitation, F = ma

for the apple, but an apple-bound observer would deny that F = ma for

the earth.

By insisting that the sun defines an inertial frame (or nearly so)

while the earth does not, Bunge dismisses Statement 2 as a “grotesque

claim” not withstanding that it is advanced by many authorities

and “hundreds of textbook authors.”

26

The laws of physics do apply in a heliocentric system but not in a

geocentric (Brahean or Ptolemaic) system.

When Ptolemy and Brahe formulated their systems, they knew of no law

of physics that

their systems would violate. Mach knew that the geocentric systems

violated the laws of

physics, but he never addressed how the heliocentric and the geometric

systems can be

considered equally actual if the laws of physics apply in one system

but not in the other.

Nor did Mach formulate an alternative set of laws to explain the

motions of the stars, the

planets, the sun, and the moon in a Brahean system.

IIID. Are there conservation laws with Mach?

The sterility of a physics without laws also can be illustrated by

considering what

happens when one has no recourse to conservation laws. For Newton,

given bodies A and

B, and U, the rest of the universe,

……

A naive Copernican account of the earth’s revolution around a fixed

sun is not actual.

What is meant today by ‘the Copernican system’ is that the sun and all

the planets orbit

around their common center of mass. The Brahean system violates

conservation of

momentum in that the solar system does not orbit around the center of

mass and Mach

gives no inkling on how to deal with this.

IIIE. The classical Doppler formulae do not support Mach

The classical Doppler effect provides crucial observations that relate

to the equal

actuality of the Brahean and Copernican systems. In the two systems,

the relative velocity

of the earth with respect to a light source is the same. Yet,

classical physics, but not SR,

predicts different Doppler shifts for the source moving versus the

observer moving. Thus,

in classical physics, one could determine whether the earth moves or

a “fixed star”

moves. This different treatment for the two motions should have

motivated Mach to pay

closer attention to SR.

To conclude, Mach did not consider the differences between the

Copernican and

Ptolemaic/Brahean systems and the many observations falsifying the

latter. Also, by

arguing that the two systems are equally actual, he denied the

universality of the laws of

physics.

IV. THE CASE OF THE THICK BUCKET

PAGE 18

1. Mach’s Principle: From Newton’s Bucket to Quantum Gravity, edited

by Julian

Barbour and Herbert Pfister (Birkhauser, Boston, MA, 1995), p. 530; 21

different

formulations are listed.

2. Denis. W. Sciama, The Unity of the Universe (Anchor Books, New

York, NY, 1961).

3. Ernst Mach, The Science of Mechanics (Open Court Publishing Co..

LaSalle, IL, 1960)

6th ed. Originally Published as Die Mechanik in ihrer Entwicklung

historisch-kritisch

darstellt . 9th Edition.

4. Isaac Newton, The Mathematical Principles of Natural Philosophy

(University of

California Press, Berkeley, CA, 1960), pp.10-11.

5. Ref. 3, p. xxviii.

6. Ref. 3, p. 279.

7. Ref. 3, p. 341, emphasis in the original.

8. Max Jammer, Concepts of Space (Harper Torchbooks, New York, NY,

1954), p. 141,

quotes the 4th German edition of Ref. 3 wherein Mach states that “…

for me, above all,

there is only relative motion, and in this respect I cannot make any

difference between

rotation and translation.” (our translation).

9. John Norton, “Mach’s principle before Einstein,“ in Ref. 1, pp. 9-

55, 36.

10. Georges Sagnac, C. R. Acad. Sci.

154, 708-710, 1410-1413 (1913). Albert A. Michelson,

“The effects of the Earth’s rotation on the velocity of light,” Phil.

Mag.

8, 716-719 (1904).

11. Robert Wood, Physical Optics (Dover Publications, Inc., New York,

NY, 1967), 3rd

ed., p. 29.

12. Richard P. Feynman, Robert B. Leighton and Matthew Sands, The

Feynman Lectures in

Physics, Vol. II (Addison-Wesley Publishing Co. , Reading, MA, 1964)

p. 14-7.

13. With terrestrial pendula one does not consider the rotation of the

pendulum bob for

the bob partakes of the rotation of the earth.

14. Albert Einstein, Ideas and Opinions (Bonanza Books. New York, NY,

(1954), p. 286.

15. The first part, up to “actual” is from Ref. 3, p. 279 (immediately

preceding Statement 1).

The remainder is from Ref. 3, p. 284.

16. Ref. 3, p. 393.

17. Ref. 3, p. 187.

18. Thomas S. Kuhn, The Copernican Revolution (Vintage Books, New

York, NY,

1959), p. 187.

19. Robert W. Brehme, Am. J. Phys.

44, 506-514 (1976).

20. Ref. 3, p. 280 (emphasis in the original). See also p. 271.

21. Ref. 3, p. 160.

22. Mario Bunge, Am. J. Phys.

34, 585-596 (1966).

23. Albert Einstein, “Autobiographical notes,” in Albert Einstein

Philosopher Scientist, edited

by Paul Schilp (Tudor Publishing Co., New York, NY, 1949), p. 21.

24. John Earman, World Enough and Space-Time, Absolute Versus

Relational Theories of Space

and Time (MIT Press, Cambridge, MA, 1989).

25. Ref. 23, p. 69.

26. Ref. 22, p. 589. Bunge lists Duhem, Pearson, Le Roy, Goodman,

Reichenbach, and Frank as

authorities who agree with Statement 2.

27. Ref. 3, p. 284.

28. Joseph Norwood, Jr., Intermediate Classical Mechanics (Prentice

Hall, Englewood

Cliffs, NJ, 1979), p. 274.

29. Hans Reichenbach, The Philosophy of Space and Time (Dover

Publications, New York, NY,

1957), p. 254, and From Copernicus to Einstein (Dover Publications,

New York, NY, 1980), p.

84.

30. Ronald Adler, Maurice Bazin, and Menahem Schiffer, Introduction to

General

Relativity (McGraw Hill Book Co., New York, NY, 1975), 2nd ed., pp.

437-448.

31. Carl Hoefer, “Einstein’s formulation of Mach’s principle,” in Ref.

1, pp. 67-90, 80.

32. Clifford Will, “Testing Machian effects in laboratory and space

experiments,“ in Ref. 1, pp.

365-386.

33. Ref. 24. 

In my article, written in 1988? I may have said that the geocentric and heliocentric view were equally correct, as per my previous e mail you can see that now I would not phrase it that way.

The point of the article would be that:

1) it is incorrect to say that "science disproved the geocentric model in favor of the heliocentric" or even that "science proved that the geocentric model is incorrect";

2)science does not offer any scientific objection to someone claiming some religious truth that in some sense the earth is the "center" of the umiverse. 

All physics experts (the dispute is negligible if it exists

> at all)

> > > >agree on

> > > >the heliocentric model of our solar system. They are well

> educated in

> > > >Einstein's theory(s) of relativity amongst other concepts

> developed> > >during

> > > >the last century (an important one being gravity, as explored by

> > > >Einstein's

> > > >theory of General Relativity). Their response to people's

> attempts at

> > > >explaining the geocincracy of our solar system using

> Einstein's theory

> > > >of

> > > >relativity have been to neglect it, because based on ALL accepted

> > > >principles

> > > >it is wrong.

> > > >

> > > >The ususal explanation given is that two objects (namely the

> Earth and

> > > >our

> > > >Sun) go around each other it is impossible to tell which is

> orbitting> > >which

> > > >etc. BUT the concept of gravity means that in a system with

> our sun and

> > > >the

> > > >earth, there is no possibility that they can co-revolve (the

> earth has

> > > >to

> > > >revolve around the sun whether the sun is staionary or not

> due to its

> > > >mass

> > > >relative to the Earth). The major point here is that the

> theory of

> > > >relativity is in favour of a helicentric model, and an

> attempt to prove

> > > >otherwise using a single concept taken out of context is

> insufficient.> > >It is

> > > >simply wrong (even hypocritical) to attempt to explain that

> they can

> > > >co-revolve using Einstein's relativity principles, but not

> address the

> > > >issue

> > > >of all his other work on relativity, which _proves_ the

> opposite. How

> > > >can

> > > >you select certain parts to use, but neglect others?

> > > >

> > > >This in addition to massive amounts of data collected from

> ground/space> > >satellites, space probes etc. solidify the

> heliocentric model. Although

> > > >it

> > > >is our belief that against all this data and evidence the

> Earth still

> > > >remains at the centre of the universe, how can this be? 

From: Avi I Rabinowitz <air1@nyu.edu>

To: tzippy <yerushabel@yahoo.com>

Cc: 

Bcc: 

Date: Mon, 29 Oct 2007 23:09:19 +0200

Subject: Re: geocentrism

Hi

Thank you for your note.

I have written against alleged disproofs of the torah etc, and about the issue of geocentrism, but never in favor of a view which claims that the Earth is actually the center of the universe or stationary etc in any scientifically meaningful sense.

Thank you

Avi

----- Original Message -----

From: tzippy <yerushabel@yahoo.com>

Date: Wednesday, October 24, 2007 7:22 pm

Subject: geocentrism

To: air1@nyu.edu

> Dear Dr Rabinowitz

> 

>  this letter in the Jewish Press

>  http://www.thejewishpress.com:80/displayContent_new.cfm?contentid=25322&mode=a&sectionid=59&contentname=Letters_To_The_Editor&recnum=0&subid=23694

> 

> 

>  drew these letters

> 

> http://www.thejewishpress.com/displayContent_new.cfm?contentid=25404&mode=a&sectionid=59&contentname=Letters_To_The_Editor&recnum=1&subid=23694

>

>  <

>   

> 

> http://www.jewishpress.com/displayContent_new.cfm?contentid=25463&mode=a&sectionid=59&contentname=Letters_To_The_Editor&recnum=1

>

>  <

> 

> 

> 

> 

>  They do not seem to be in accord with Relativity.

> 

>  I think they warrant a reply by an expert like yourself

> 

>  Tzipporah. 

Dear Dr Rabinowitz,

I was reading your fascinating article here

http://www.pages.nyu.edu/~air1/GeoCentrism%20&%20EgoCentrism,%20Existentialist%20Despair%20&%20Significance.htm

If you could clear up a couple of points I would appreciate it.

" Another possibility – raised by Riemann 150 years ago and later by

Einstein – is that the universe is ‘closed’ and so it has no end, but

also no unique center (see discussion later on). Either way neither

the Earth nor its sun are at the center of the universe.

"

does this mean that if the universe is closed it would have a centre

"it is equally true scientifically to say that the earth rotates about

the sun as to say that the sun rotates about the earth". What is true

is that THEY ARE IN RELATIVE ROTATION: and THAT'S ALL THERE IS TO be

said from the scientific viewpoint.

would you say the same about the moons going around jupiter, that it

it cannot be determined which revolves around which.

"However by the time of Copernicus it was realized that visually

unambiguous geocentrism' is false; were one to stand on the sun and

look at the Earth one would feel the sun is stationary and that the

Earth goes around it"

what about standing on mars, or outside the solar system

"Also, scientific belief holds that:

·                 there is no scientifically definable unique center

to the universe;"

what about an open uinverse

"Some have also thought that my article claims Judaism believes the

Bible teaches this type of geocentrism, whereas in fact it is my

impression that most Orthodox Religious sages today and in previous

times do not feel the Bible teaches this at all; "

is the talmudic and  rishonim's model a geocentrist one based on

pesachim 93, in maskanah.

" since they are not in motion relative to each other and one tries to

really take this frame seriously then one is going out of the realm of

validity of general relativity and physics and if so then whatever

keeps the Earth where it is as opposed to everything else in the

universe which is moving around it (eg the sun) also keeps the

satellite there."

it is only in stationary orbit at a certain altitude and speed, which

is described newton's law of gravitation.

is it not a fantastic co-incidence that this new force (which cannot

be described scientifically) accounts for this stationary sattelite

just at that altitude and speed predicted by newton's law and does not

work at any other combination of altitude and speed.

what is the difference between that and saying that we have not proven

that heat expands metal, it could be another unknown force that does

it. if you say the expansion is in proportion to the heat applied.,

why not say that evidence for heliocentrism would be it only

stationary where newton's law of gravitation would predict it to be

stationary in a heliocentric universe

yours

shloime reich

...

[Message clipped]  View entire message

Avi I Rabinowitz <air1@nyu.edu>

Tue, Oct 19, 2010, 11:49 PM

to sol

does this mean that if the universe is closed it would have a centre

AR: No. Just as the surface of a sphere has no center.

would you say the same about the moons going around jupiter, that it cannot be determined which revolves around which.

AR: Wronq concept. Not that we can;t determine which is the one being 'revolved around', rather that there is no meaning to specifying one as different than the other, only relative motion is definable in a meaningful manner. But simplicity is a different thing, see for example quote from Reichenbach.

what about standing on mars, or outside the solar system

AR: The point is that no place is unambiguously standing still and so no place can be the referent point for making an unambiguous determination.

what about an open universe

AR: same, no center.

For example, all points are the original point of the big bang.

About gmara, better ask a talmid chochom. BTW, only chabad believes Judaism mandates geocentrism - ask several non-chabad talmidei chachamim to get a variety of opinions. Also, see the various discussions on the web about this, and the statement about whether the chachomim or the Greeks prevailed etc.

re sattelite: not that we believe there is a force. You need to understand about 'local frame' and the equivalence principle, etc.

Anyone who is SERIOUSLY interested in this subject MUST learn general relativity thoroughly. Meaning, take a mathematically-solid course in GR at a good university, a credit-bearing course with written exams requiring deep understanding of the equations so that you can have a reality check as to whether or not you understood it all. If so, you'll be equipped to see whether you can make a good argument in favor of geocentrism.

Thanks very much for your kind words about the article.

I won't respond at greater length since some people never give up on this topic, and I don;t know if you are one of them. Unfortunately I have as much interest in discussing geocentrism with believers in it as I do discussing 'rebbe as moshiach' or 'moshiach can die and be resurrected' with chabad meshichistim, and as the patent office has in discussing perpetual motion machines  :)

In any case, if you are not a geocentrism believer just curious, there are various sources you can read. I have no interest in this subject anymore myself, the article I initially wrote on the subject was written many years ago.

Behatzlachah!

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sol reich <solreich2@googlemail.com>

Fri, Oct 22, 2010, 2:33 AM

to me

Dear Dr Rabinowitz,

thank you for your prompt reply.

I am not a geocentrist believer, rather I did not quite follow how

those who admit geocenticsm as equally valid in accordance with GR

would answer the various proofs given for heliocentrism and rotating

earth. you answer geo-stationary satelites what about  eg Foucault

pendulum  and parallax. (although you seem to be saying you do not

have to answer those proofs to make it equally valid)

On 10/19/10, Avi I Rabinowitz <air1@nyu.edu> wrote:

> does this mean that if the universe is closed it would have a centre

> AR: No. Just as the surface of a sphere has no center.

I understood from this link that it cannot be ruled out that the

universe has a centre

http://www.phys.ncku.edu.tw/mirrors/physicsfaq/Relativity/GR/centre.html

It is less well known that Lemaître found a more general class of

solutions that describe a spherically symmetric expanding universe.

These solutions, now known as Lemaître-Tolman-Bondi (LTB) models,

describe possible forms for a universe that could have a centre.

Since the FLWR models are actually a special limiting case of the LTB

models, we have no sure way of knowing that the LTB models are not

correct.  The FLWR models may just be good approximations that work

well within the limits of the observable universe but not beyond.

>

> would you say the same about the moons going around jupiter, that it cannot

> be determined which revolves around which.

> AR: Wronq concept. Not that we can;t determine which is the one being

> 'revolved around', rather that there is no meaning to specifying one as

> different than the other, only relative motion is definable in a meaningful

> manner. But simplicity is a different thing, see for example quote from

> Reichenbach.

>

so are you saying  (1)that it can be proven that the earth 'really'

revolves around the sun, but it is scientifically meaningless.

(2) or that it has not even been proven that the earth 'really'

revolves around the sun.

(3)If I wanted to send a rocket to a moon of jupiter, would it not be

important to know which is really revolving around which or if I

wanted to know the speed of a planet I would use kepler's third law,

which depends on the sun being the centre of the solar system not the

earth

you say:

All the following statements are FALSE (not only from the scientific

viewpoint):

.....................

"science has proven that the sun does NOT rotate about the earth"]

newton's  gravitational laws show that the sun does NOT rotate about

the earth as  as a big body cannot revolve around a small body. the

fact that the reality is scientifically meaningless (I would have

thought) does not mean the reality changes to a metaphysical belief.

> what about standing on mars, or outside the solar system

> AR: The point is that no place is unambiguously standing still and so no

> place can be the referent point for making an unambiguous determination.

I understood you to say before that we may be able to  make

unambiguous (although 'meaningless') determination that the moons of

jupiter revolve around it despite the fact that no place is

unambiguously standing still

you say

"

However by the time of Copernicus it was realized that visually

unambiguous geocentrism' is false; were one to stand on the sun and

look at the Earth one would feel the sun is stationary and that the

Earth goes around it"

I would have thought by the time of Copernicus it was realized that

wherever you go in the universe, outside the solar system you would

see the earth rotating around the sun.

(the only difference different  observers would see, depending upon

their own speed relative to the solar system would be the speed of

rotation of the earth around the sun)

so copernicus would define himself as a visually unambiguous heliocentrist

yours

shloime

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Avi I Rabinowitz <air1@nyu.edu>

Tue, Oct 26, 2010, 4:10 PM

to sol

Hi. Glad to know you are not a flat-earther :)

I don;t have time unfortunately to answer more questions, I'll try in brief....

re 'center': there is no way to absolutely know for certain that the universe is not on an elephant's back, that perhaps what we think of as the universe is not actually a small non-representative sample of something very strange etc, and maybe the universe has a center and there are elves living there but we are far away form the center and in our region everything seems homogenous and there's evidence for a big bang etc. We take what seems most 'reasonable' and make a great assumption, the Copernican assumption of "perfect cosmological principle', and that's where GR and no-center comes in. Things however may change, but not because we are at the center of the universe, a belief that messed people up for a while and scientists are willing to make the opposite mistake for now.

re 'really': nothing 'really' goes around something else. Only relative motion can be defined, until there is discovered some absolute frame that is proven to be (or defined as) stationary.

re: if I wanted to send a rocket to a moon of jupiter: all you need is the relative motion of Earth and Jupiter's moon.

that's all I have time for, at least on this subject,

best wishes,

Avi

I wonder if you could explain me something. if you are more than a 100 million miles from the sun, I believe you will never see the sun rotate around the earth, no matter what speed or orbit or how many somersaults you may be doing.

so

I did not understand why is that not proof that the sun does NOT rotate about the earth"

yours

shloime reich

Avi I Rabinowitz <air1@nyu.edu>

Mon, May 7, 2012, 2:44 AM

to sol

hi

The equations are simplest from a frame centered on the sun, or at the center of mass of the solar system etc. However in theoretical physics although what we would consider maximal simplicity of equations is an indication that the choice of coordinates (frame) maximally reflects the symmetries of the situation, nevertheless it is not considered as a criterion which determines ‘what the situation ‘REALLY’ is”. Only objectively measurable criteria are acceptable and these turn out to be only relative measures. From the Earth it seems obvious that the sun is going round the Earth, and from the Sun it seems the reverse and if we are spinning on the sun it seems the sun, or far away from it, it seems as though the sun is going round us etc, there’s no one frame which is chosen by universal law to be the one from which one 'correct' determination can be made, 

To go into this further you would have to read a lot about invariance & covariance, and their relation to the ‘principle of relativity’; about coordinate choices and their ramifications; about what constitutes ‘simplicity’ (for example experts all feel that general relativity is simpler than Newtonian theory), etc.

avi

..................

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sol reich <solreich2@gmail.com>

Mon, May 7, 2012, 6:54 PM

to me

Avi,

thanks for your reply

you say

"and if we are spinning on the sun it seems the sun, or far away from it, it seems as though the sun is going round us etc"

I did not follow from where in the universe (besides the earth) you were saying it seems the sun is going round us.

thank you

sol

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Avi I Rabinowitz <air1@nyu.edu>

Mon, May 7, 2012, 7:31 PM

to sol

anytime you move anywhere, from your perspective the sun is moving.

Read about the topics I mentioned, and about mach's principle. You'd need to invest lots of time though.

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sol reich <solreich2@gmail.com>

Mon, May 7, 2012, 9:51 PM

to me

Avi,

I understand that anytime you move anywhere, from your perspective the sun is moving, but is there anywhere

(besides planet earth)from your perspective where the sun is moving around planet earth ?

shloime

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Avi I Rabinowitz <air1@nyu.edu>

Mon, May 7, 2012, 11:28 PM

to sol

Earth is enough.

It's good that you are trying to think deeply about these things. If you are interested in general relativity though, not just this specific topic, I can send you some material to start you off....did you take calculus-based physics?

..

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sol reich <solreich2@gmail.com>

Tue, May 8, 2012, 1:36 AM

to me

Avi,

so just to get clear are you saying even if it would be proven that every where in the universe you look it seems that the earth revolves around the sun, (except for planet earth) , it is still incorrect to say that  'really' the earth moves around the sun as all we have in the universe is relative movement.

I learned some considerable time ago high school calculus maths

shloime

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Avi I Rabinowitz <air1@nyu.edu>

Tue, May 8, 2012, 2:04 AM

to sol

Basically yes.

Note that they both orbit their mutual center of gravity (for some systems of two bodies that could be within one of them)

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sol reich <solreich2@gmail.com>

Tue, May 8, 2012, 5:16 AM

to me

Avi,

so from the perspective of the sun orbiting the earth, is the sun orbiting the earth's centre of gravity or the sun's centre of gravity ?

shloime

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Avi I Rabinowitz <air1@nyu.edu>

Tue, May 8, 2012, 6:06 AM

to sol

Mutual center

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sol reich <solreich2@gmail.com>

Tue, May 8, 2012, 2:46 PM

to me

Avi,

the mutual centre of mass  of the sun and earth is I believe 280 miles from the centre of the sun.

are you saying from the earth perpective, this is what the sun is orbiting ?

shloime

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Avi I Rabinowitz <air1@nyu.edu>

Tue, May 8, 2012, 6:48 PM

to sol

From the relative perspective .

.....

misunderstanding of my article, and lacking a link to it: https://merrimackvalleyhavurah.wordpress.com/2016/07/06/geocentrism/

couldnt find contact info for them, only posting a comment on the page with FB or  g+ etc, ddnt want to, I wrote to anothe rhavurah asking if they had the email for htis one.

chabad in that community lists other shuls etc: https://mvjf.org/community-center/our-community/our-community

since they are chabad, they'll probably like pointing out the misunderstanding except that they'll have the opposite misunderstanding!

I created a new googlesite and placed the article there: https://sites.google.com/s/1Eq-YbGL2uFzn5Cq5t2oJ6GuCN77JY86B/p/1IxgPERD9XfaIH5LYRmTfR1tJlG9pNMfK/edit?authuser=1