In the summer of 1975, an encounter took place between Rabbi F.R., a Lubavitcher chassid, and Mr. A.P., a “modernized” American Jew. Rabbi R. was seeking to influence Mr. P. toward a greater commitment to Torah observance, which the latter dismissed as “archaic” and dismally outdated. In the course of the conversation, Mr. P. said, “Are you telling me that every law and practice mentioned in the Torah, written thousands of years ago, must be accepted at face value today?” “Certainly,” replied Rabbi R. “The Torah is eternal, and is equally pertinent to every day and age.” “The Torah states that the sun revolves around the earth,” countered Mr. P. “Do you believe that as well?” “Yes, I do,” replied Rabbi R. “Well, you might believe that,” said Mr. P., “but no rational, self-respecting inhabitant of the 20th century does. I’m sure your rebbe, Rabbi Schneerson, doesn’t!” “I’m sure he does,” said the rabbi. “I’m willing to wager anything that he does not,” said Mr. P. “In fact, I’ll say this: If the Rebbe states that he believes that the sun revolves around the earth, I will become a Torah-observant Jew and convince everyone I know to do the same!” “Would you put that in writing?” challenged Rabbi R. “No problem,” said Mr. P.
Soon after, Rabbi R. received the following letter:
Dear Rabbi R____
As per our conversation of today… I did say to you, and am submitting the same in writing by means of this letter, that if the Rebbe would make a public statement to the effect that… since the Talmud states that the sun revolves around the earth, it is therefore his firm belief that the sun does indeed revolve around the earth, that I will:
(a) personally observe the laws of taharat hamishpachah,  tefillin and Shabbat; and
(b) influence my friends and colleagues to do the same.
It is, however, more than obvious to me that the Rebbe will not, in any way, make such a ridiculous statement, because
(a) he does not wish to be labeled as a fool,
(b) he himself is not as foolish as some of his ardent but hypnotized followers.
I predict, with no hesitation, that I will not hear any more about this matter from you or from the Rebbe…
I must tell you that I feel a deep personal hurt when people such as you make such asinine, ridiculous statements and then hide your abysmal ignorance behind the facade of “Torah.” Don’t you realize you can still be believers and not live 500 years behind the times?
Mr. P. received not one but two separate letters in reply from the Rebbe, plus a third, cover letter, which read as follows:
Greetings and blessings!
Your letter, addressed to Rabbi F____ R____, reached me … In view of its content, I naturally take this first opportunity of replying to it.
Not knowing whether you are more interested in the practical implication, or/and in the scientific aspect, I am writing two separate replies, enclosed herewith, which you can read in the order you prefer.
With esteem and blessing,
P.S. It is surely unnecessary to add—though I am adding it for the record—that I take for granted that you will keep your commitments with regard to the practical aspects of your letter.
One letter read:
… In reply to your question relating to the matter of the motion of the sun and the earth, whether the sun revolves around the earth or the earth around the sun,
It is my firm belief that the sun revolves around the earth, as I have also declared publicly on various occasions and in discussion with professors specializing in this field of science.
In view of the above, I have no objection, of course, if you wish to make this view known to whomever you choose…
The other letter read:
… This is in reply to your inquiry on the question of the rotation of the sun and the earth in relation to each other, namely, whether the sun revolves around the earth, or the earth around the sun, and which view is to be accepted, etc.
I presume you have in mind the scientific view, i.e., what science has to say on this question, and I will address myself to this aspect.
It is well known that this was a controversial issue in ancient and medieval science. However, since about half a century ago, with the introduction of the theory of relativity, the latter has been universally accepted as the basis of modern science…
One of the conclusions of the theory of relativity is that when there are two systems, or planets, in motion relative to each other—such as the sun and the earth in our case—either view, namely the sun rotating around the earth, or the earth rotating around the sun, has equal validity. Thus, if there are phenomena that cannot be adequately explained on the basis of one of these views, such difficulties have their counterpart also if the opposite view is accepted.
Secondly, the scientific conclusion that both views have equal validity is the result not of any inadequacy of available scientific data, or of technological development (measuring instruments, etc.), in which case it could be expected that further scientific or technological advancement might clear up the matter eventually and decide in favor of one or the other view. On the contrary, the conclusion of contemporary science is that regardless of any future scientific advancement, the question as to which is our planetary center, the sun or the earth, must forever remain unresolved, since both view[s] will always have the same scientific validity, as stated.
Thirdly, it follows that anyone declaring that a person who chooses to accept one of these systems in preference to the other is a fool, while one who accepts the other is a wise man—such a judgment shows that the person making it is ignorant of the conclusions of modern science, or that he has not advanced beyond the science of Ptolemy and Copernicus…
A further point might be added, though perhaps not pertinent to our discussion. It is that every person, including modern scientists, actually has three options to choose from in this matter: (a) that A revolves around B, (b) that B revolves around A, (c) that A and B revolve around each other. But such a choice cannot be dictated by science; it would be one’s personal choice and belief.
What has been said above is—to repeat—the deduction of the theory of relativity, as it is expounded in various scientific texts, and it can be checked with any scientist who is thoroughly familiar with the said theory. Of course, on the elementary and high-school level, science in general, and the so-called Solar System in particular, is taught from relatively simple textbooks, and the change in the scientific attitude towards the subject under discussion is not emphasized. But, as stated, it would be quite simple to verify it with any scientist who knows this particular field…
. Ecclesiastes 1:4, and numerous other scriptural and talmudic sources.
. The Torah’s laws of family purity
. The letters have been slightly abridged, due to space limitations.