Tuesday, May 24, 2022

Chazal and NASA

Did Chazal (the Sages of the Talmud) have supernatural knowledge of the natural world? Do their statements prove Torah MiSinai? One alleged "proof" to this effect is regarding the length of the lunar month.

The argument goes as follows: In the Gemara, Rabban Gamliel says that the average length of the lunar month is 29.530594 days. NASA, with years of research using satellites, telescopes, laser beams and supercomputers, calculated the mean length of the lunar month as 29.530588 days. The difference between this figure and that used by the Sages is only 0.000006! How could Chazal have calculated it to such accuracy? They must have had supernatural sources of knowledge.

This sounds amazing!

But is it true?

I've spent 25 years researching such alleged proofs based on incredible statements by Chazal. I approached them initially with a very trusting (and naive) perspective that since they are proposed by dynamic and brilliant rabbis, they must be true. Much to my dismay, every time I looked into such arguments, I found that they fell into one of three categories:

A) They were ambiguous statements that could be read in all kinds of different ways

B) They were things that non-Jews also knew, and do not require supernatural sources of information

C) They were things that are not actually true.

The lunar cycle argument is no different.

First, let us consider whether the claim is, on the outset, reasonable. Recall that Chazal did not know where the sun goes at night. Accordingly, it does not seem that they had supernatural sources of knowledge for astronomy.

Still, one could argue that perhaps the supernatural knowledge was only for particular things. So let's look at what Rabban Gamliel actually said, and the context in which he said it:

"The Sages taught in a baraita: Once the sky was covered with clouds, and the form of the moon was visible on the twenty-ninth of the month. The people thought to say that the day was the New Moon, and the court sought to sanctify it. Rabban Gamliel said to them: This is the tradition that I received from the house of my grandfather: The monthly cycle of the renewal of the moon takes no less than twenty-nine and a half days, plus two-thirds of an hour, plus seventy-three of the 1,080 subsections of an hour." (Rosh HaShana 25a)

Looking at the Gemara, we see that it is being misrepresented. Rabban Gamliel was not giving the average length of the lunar month. Instead, he was giving the minimum length of the lunar month. He explicitly says this ("takes no less than") and it's also the context, in which he was responding to a question about whether it could be Rosh Chodesh already. The lunar months actually vary in length by several hours, because the speed of the moon’s rotation around the earth is not uniform. And as a minimum length of the month, Rabban Gamliel's figure is several hours off.

But in any case, not only do we no longer have Rabban Gamliel's statement being scientifically accurate, we have an innate problem. The duration that he gives as being the minimum length of the month is actually the mean length of a lunar month, as used in the Jewish calendar! Several Acharonim already recognized this problem. It is therefore presumed that what we have here is a textual interpolation (see Sacha Stern, Calendar and Community. A history of the Jewish calendar second century BCE – tenth century CE, Oxford, 2001, p. 201). What Rabban Gamliel originally said - which makes sense as a response to the situation discussed in the Gemara - was that the monthly cycle is no less than 29 days. Much later, someone added the additional units of time to the text, mistakenly thinking that it should be "corrected" to the mean value.

There is no way to know when this textual interpolation took place. But what we do know is that, whenever after Rabban Gamliel the average length of the lunar month was known, the exact same figure was known in antiquity by other peoples - and even earlier.

The exact duration of the month found in the Gemara was already given by Ptolemy, in base-sixty notation, in the 2nd century CE. He in turn was quoting Hipparchus, from the second century BCE - nearly two hundred years before Rabban Gamliel. And Hipparchus in turn had received this value from the ancient Babylonians! There have even been discoveries of Babylonian cuneiform tablets which contain this number.

In summary: Rabban Gamliel's statement, as the minimum length of the month, is not actually correct. As a later interpolation of the mean length of the month, which was employed in the rabbinic calendar, it is correct - but the same value was already known much earlier by the Greeks and even earlier by the Babylonians.

So not only is this not a proof of Torah MiSinai - it's actually a worse problem. The people using this as a "proof of Torah" argue that such knowledge can only come from a Divine source! So, according to them, this is proof that the Babylonians had supernatural knowledge of the natural world, and evidence that their religion was the One True Religion! 

Fortunately for the rest of us, they are mistaken. You don't actually need supernatural sources of knowledge to come up with this figure. The Babylonians were simply very meticulous astronomers. By measuring the duration between eclipses, one can figure out the mean length of the lunar month. (See here for an extremely technical discussion.)

Now, if you're a person that likes these kinds of proofs, and you're thinking that I'm just a bitter, cynical person, consider this: I used to be just as starry-eyed a believer in these proofs as you. The reason why I became cynical is precisely because I was taken in by such proofs which turned out to be fundamentally flawed. As Rambam says, the problem with using flawed proofs is that when people discover the flaws, they lose confidence in everything you present. If you use such "proofs" with other people, you'll just be turning others into cynics.

Don't try to "prove" Judaism with gimmicks. It doesn't work and it can backfire badly. Instead, present the extraordinary history of the Jewish People, culminating in our miraculous return to our homeland, along with the incredible meaningfulness and value of a Torah-observant lifestyle. 

 

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67 comments:

  1. Genuine question: when Chazal talk about measurement of hours and fractions of hours, what "hour" are they talking about?

    My understanding is that a day divided into 24 equal hours is a relatively modern innovation, while Chazal's "hours" are (AFAIK) always "variable hours" (daytime and night-time each divided into twelve hours of equal length) and thus their durations differ through the course of the year.

    Plus ancient chronometry would not have been terribly precise to begin with.

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    1. "My understanding is that ... Chazal's "hours" are (AFAIK) always "variable hours" "

      No, there are also "Shaos Shavos", as needed for our context and elsewhere.

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  2. It takes accurate timekeeping from one lunar eclipse to another, the only case where you know for sure the moment of lunation. To the cheileq. The truth is, the Babylonians getting the molad correct would be Divine Intervention too.

    And in fact, they didn't. What they actually got was a more amazing value.

    The average time between new moons (lunation) is not a constant
    down the centuries. It is getting longer; in other words, the moon is
    slowing down. Energy is being spent pulling the tides around. And that drag is making the moon's trip around the earth take longer.

    Also, the earth is spinning slower for the same reason. In other words, our units of measure -- days, hours (day / 24) and chalaqim are longer than Chazal's.

    The Molad recorded in Babylonian tablets was first used just around Galus Bavel. (Plus or minus a missing king problem.)

    But it was most accurate a millennium later, when our calendar was established.

    First, I am not sure we got the mean lunation from the Babylonians and not the other way around. After all, our intelligentsia were drafted into their royal court. But however the value we use eventually reached Rabbi Hillel and his Beis Din, the "coincidence" smells strongly of Divine Intervention.

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    1. I believe you would use time between solar eclipses as the middle point of the eclipse is easier to determine. As presumably the calculation would use multiple of these and an averaging process, combined with the fact that the Babylonians kept eclipse records over hundreds of years would help with accuracy.

      You are correct that the accuracy of the calculation was maximal some centuries after it was first discovered (and broadly in the era of the setting of the current calendar, however it was also some time after Raban Gamliel allegedly said it).

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    2. Yes, I was thinking more about the meta-issue of "isn't the precision amazing" and not Rabban Gamliel. The fact that during Galus Bavel we knew the *wrong* time for the average molad but one that would most correct just when we needed it to set up a calendar is amazing to me.

      I also think it is likely that Rabban Gamliel simply misremembered the mesorah, taking a value that we knew -- either from Bavel or from "HaChodesh hazeh lachem" and we taught Bavel, and assigning it the wrong meaning.

      But while "amazing" because it has to mean *something*, I am not sure what. A better choice of calendar might have been made had Hashem provided us with a value for the molad that was most accurate on average across the time between the last Sanhedrin and the next one. Not on the day the last Sanhedrin met.

      Still, there has to be something signficant there. Unlike RNS's assertion in the original blog post.

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    3. "there has to be something signficant there" - seems to me that's the sort of assumption that the OP was precisely trying to avoid. Just because there is an interesting coincidence doesn't mean there *has to* be something there.

      "he mean synodic month used for the modern Hindu calendar, as documented in the Surya Siddhanta around 1000 AD, is 29+7087771/13358334 days = 29 days 12h 44m 2+1777862/2226389s (the fraction is almost 4/5 second), which was almost 1/3 second too short for the era when Hindus started to use that calendar, but is actually essentially perfect for the present era" (quote from Dr. Irv Bromberg, University of Toronto, Canada where most of my information on this area comes from).
      Does the fact that this hindu calculation is perfect in our era "have to" have some significance? Maybe the hindu gods are particularly strong in our era? Or perhaps it's a coincidence!

      As an aside until I just read the quote above I wasn't aware of the hindu calculations (there is another older one) and in particular this one which is about the same accuracy as the Babylonian one we use. Again this shows that actually calculating this sort of things without modern tools is achievable even if highly impressive. There is no need to assume a divine source.

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    4. Yoni, yes. I disagree with that aspect of the post.

      First, because claiming that in general Chazal didn't know science better than their peers doesn't require believing that about the molad. Since Chazal state that Hashem showed Moshe how to do the calendar. The value of the molad could have been included.

      Second, because whether it was revealed at Sinai or something we learned from the Babylonians, the coincidence is just huge! We had a value that was in error, but the error was just the one needed for the value to be right when the calendar moved to calculated data. It is hard to avoid concluding that siyata diShmaya was involved. G-d does work through nature, setting the conditions just right for the Babylonians to make the perfect error for our needs is consistent with the kind of G-d who set things up just right for the species He wanted to evolve into existence.

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    5. Micha, you're whole "isn't amazing that..." bit is rather less amazing now that we're using the same calendar ~1800 years later. Wonderful coincidence for the time, perhaps, but not much of a miracle if it's no longer accurate.

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  3. The rabbi is 100% right. I had the same problem as well.

    The problem also is in reverse, when Rabbis mock those who believe in evolution or biblical criticism as fools.

    (Contrast that to Rabbis such as Rabbi Slifkin and Sacks, who use evolution to show God's handiwork, or Rabbi Breuer, who takes biblical criticism seriously - and shows how the 4 sources show an amazing unity as well and tackles the subject seriously.)

    The last Gadol to tackles such topics was Rav Kook, and he was ostracized. We need more actual gedolim, not mockers or kiruv klowns.

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    1. "The last Gadol to tackles such topics was Rav Kook, and he was ostracized."

      Rav Dessler, who was later, also tackled these topics (as did others less known), but wasn't ostracized, . Rav Kook was ostracized for other reasons. His stance on this issue is hardly known to the ostracizers; likewise probably the general public.

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    2. On the subject of R Dessler, I came across an interesting recording from a low key Rav who says great Halachah Shiurim on OC & YD. AFAIK he has no expertise in rationalist Rishonim.

      In the course of a Halachic discussion, he mentions Rav Carmel's note in Michtav M'Eliyahu about lice etc. printed back in the 1950s(?). Then he says that there's a letter in which R Eliashev opposed it. And there's a letter from R Carmel in the 2000s confirming his 50 year old note (= his re-Haskama to R Slifkin). So in Halachah R Eliashev takes precedence over R Dessler and R Carmel. Then he adds, but he says clearly that he's only making an OBSERVATION; he doesn't want to get into anything nor voice an opinion on the matter, but he notes that:

      “The [best-selling] Michtav M'Eliyahu had already gone through 13 editions [in the 50 year interim]. Certainly many T”Ch had learned it. Yet we never heard anyone find fault with this piece. This would indicate agreement with RD and RC. So it's not them alone arguing on RE, but also the assumed many T”Ch who agreed with them.”

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  4. If you want to have some fun with people, when the subject of the 29.5 day lunar cycle comes up, tell them that they are wrong. The real lunar cycle around the Earth is about 27-1/3 days!! It all depends on what your reference point is; whether it's the Sun or the distant stars. For an interesting explanation of the difference, see this Wikipedia reference: https://en.wikipedia.org/wiki/Orbit_of_the_Moon

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  5. In defense of the unknowing who use the lunar "proof", it should be noted that they have a distinguished, but apparently incorrect, source. This is Abarbanel in Shmos 12:1 citing Ptolemy.
    עד שמפני עוצם החכמה שהיתה בחכמי ישראל בדבר הזה הפליג בטלמיוס היוני לשבח ולפאר מי שהמציא זה המחזור של י"ט שנה במלאכ' העיבור אשר לבני ישראל וכתב שזה יוכיח שהיתה ביניהם נבואה
    https://www.sefaria.org/Abarbanel_on_Torah%2C_Exodus.12.1?ven=Yalkut,_Sifsei_Chachomim_Chumash,_Metsudah_Publications,_2009&vhe=Torah_Commentary_of_Yitzchak_Abarbanel,_Warsaw_1862&lang=bi&with=all&lang2=en

    So they're merely not up to date.

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  6. "Don't try to "prove" Judaism with gimmicks. It doesn't work and it can backfire badly."

    Rav Hirsch says the almost the same in his letter to RHW. Yet Rambam on this very subject (פה"מ ר"ה ב-ו) tells of an 'Adam' who did so.
    ואני תמיה מאדם יכחיש הראות ויאמר כי דת היהודים אינה בנויה על ראיית הלבנה אלא על החשבון בלבד, והוא מאמין אלו הכתובים כולם, ואני רואה שהרואה זה אינו מאמינו אבל היתה דעתו בזה המאמר להשיב אחור בעל דינו באי זה צד יזדמן לו בשקר או באמת, כיון שלא מצא מציל לנפשו מהכרח הויכוח.

    R Chavel's notes to R Bachye Shmos 12, citing Shi"r, tells us that this 'Adam' was one of the most celebrated authorities of the Gaonic period.

    Many don't have access to the counter-evidence you're publicizing. They're inspired by a gimmick. (Some have access to you and you spoiled it for them.) Others aren't. Now we need to calculate if there's a net gain or loss. Has this calculation been done and/or can this be done?

    Rambam also held of "necessary truths" (= lies) where necessary. No concern for a backfire.

    Maharal in the last 2 pieces in Pirkei Avos says that Rambam on (at least) 2 occasions invented necessary truths of his own. We're now centuries later but where's the bad backfire?

    The backfire is from insistence ... (will continue).

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    1. The backfire is from insistence ... itself. When you come on heavily against the other view, there's likely to be a reaction. These things are best done individually, where you can gauge what sits well with the person, and you receive immediate feedback and adjust as needed. If not individually, mention all the alternatives respectfully--each person will gravitate to what sits best with them.

      Also the art of persuasion isn't only information. Being friendly in person and in your writings goes far for achieving your goals.

      In a closed Chareidi environment, you actually can be heavy handed, cause they're used to it--in general Chareidim are in a sense more intense--provided you preach against antagonizing others.

      The goof of the Cherem against you was their displaying their heavy handedness to larger Jewish society. A mild statement (and oral as opposed to written) that your books aren't for Chareidim would have fared much much better.

      Technically you are also too heavy handed against them. But they've never put down their weapons. They banished you from the Chareidi world, but when one studies the subject one sees that they stole and still steal the "territorial rights" of an author. Until they own up to Judaism sacred sources, they have no right to complain. In my dreams, they do own up....

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  7. It's unfortunate that many seem to feel the need draw inspiration from Chazal from their knowledge of science, not their knowledge of Torah!

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    1. If we could deliver to those unfortunates, should we not?

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  8. The Rambam writes (Kiddush HaChodesh 17:24) that it's not unheard of that we had the astronomical knowledge independently, but can still rely on non-Jewish sources, since these things are verifiable through observation:
    The rationales for all these calculations, and the reasons why this number is added, and why that subtraction is made, and how all these concepts are known, and the proofs for each of these principles are [the subject] of the wisdom of astronomy and geometry, concerning which the Greeks wrote many books.

    These texts are presently in the hands of the sages. The texts written by the Sages of Israel in the age of the prophets from the tribe of Yissachar have not been transmitted to us. Nevertheless, since these concepts can be proven in an unshakable manner, leaving no room for question, the identity of the author, be he a prophet or a gentile, is of no concern. For a matter whose rationale has been revealed and has proven truthful in an unshakable manner, we do not rely on [the personal authority of] the individual who made these statements or taught these concepts, but on the proofs he presented and the reasons he made known.

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    1. Yes, the Rambam does seem to say that we had independent knowledge of astronomy which was subsequently lost; I always saw this as not not being in agreement with a rationalist position.

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    2. "written by the sages..." sounds to me more like he is referring to something having been calculated by "sages" i.e. through logic, not transmission (he could have said written by prophets).

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    3. Good point. Also, how were the months calculated BEFORE "the texts written by the Sages of Israel in the age of the prophets from the tribe of Yissachar"?

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  9. You should stick to posts like this.

    An interpolation is certainly possible, but you haven't presented any actual proof, or even a convincing argument. It is a perfectly normal statement to state "the month is no less than X", using the precise figure. The point about Ptolemy, on the other hand, could be more germane, assuming you have presented it accurately. Some folks read Chazal in a vacuum, and don't realize that the Greeks, and in some case the Romans, were there long before them. But I'm not sure if its relevant here. What exactly is "base 60 notation"? Did he give the number as clearly as it was stated by R. Gamliel? Was his opinion known to the public? The Rabbis prided themselves on astronomical knowledge more than any other field, and R. Gamliel came from a royal lineage. Its quite reasonable to think he was in possession of knowledge quite independent of the Greeks.

    GP

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    1. "It is a perfectly normal statement to state "the month is no less than X", using the precise figure." I'm not sure what you're trying to say. Are you arguing that the Gemara is therefore mistaken?

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    2. I was referring to what you wrote, that "what Rabban Gamliel originally said - which makes sense as a response to the situation discussed in the Gemara - was that the monthly cycle is no less than 29 days." The statement as we have it, in which he gives the precise figure (and does not merely state the round figure of 'no less than 29 days") also makes sense as a response to the situation discussed in the Gemara. Thus, you have not presented any evidence to suggest interpolation.

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    3. But it's not a correct statement! That is NOT the minimum!

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    4. I don't know enough to say if it is or it isn't. But you were saying the text itself indicates an interpolation; I'm saying it doesn't.

      In any event, the real question is if the figure R. Gamliel cited was already known to the Greeks. Ptolemy is too late, and we don't know what "base 60 notation" means. The Babylonian claim, which you link to, says nothing to indicate this figure, and R. Gamliel would not have understood it anyway. That leaves Hipparchus. What, exactly, did he say? (We would need to rely on a translator of ancient Greek.) And whatever he said, would it have been known to R. Gamliel?

      I repeat, your general principle is true, viz, that sometimes statements of Chazal (including halachic ones) owe their roots to the Greeks or Romans. I'm just not sure this is a good illustration of it. We need proof, and this isnt it.

      Gn. Pickles.



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    5. @Unknown. It would have been a grammatically correct statement, however would also have been an astronomically incorrect statement. The presumption is that the text is wrong, but you are correct it could well have been Rabban Gamliel's statement that was wrong. We don't know how widely known the calculation was in antiquity, but as RNS mentioned it was known by Hipparchus. It was also coded into the Antikythera mechanism which also predates Rabban Gamliel (and possibly Hipparchus).

      The base 60 notation was used (and possibly invented) by the Babylonians

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    6. Yoni, thanks for the reply. "As the Goy goes, so goes the Jew." Gentile scholars read things into the Greeks just like Jews do into Chazal. And few of us can decipher ancient Greek (much less Cuneiform). And astronomy in general, even that of recent greats like Kepler and Copernicus, is often written in dense mathematical terms, not prose, making it very hard to understand even in one's own native language.

      The point is, we cannot properly assess what state of astronomical knowledge was actually available to R. Gamliel. We would be on firmer ground if the material was found in famous writers like Aristotle, who was widely known even in ancient times, and whose writings are in clear prose and have been scrutinized by many. But in this area, we just don't know. Considering the totality of the evidence and the circumstances, it seems to me its as likely as not - if not even more likely - that R. Gamliel possessed astronomical knowledge independent of other sources.

      GP

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    7. "The Babylonians applied the 19-year cycle since the late sixth century BC." (https://en.wikipedia.org/wiki/Metonic_cycle).

      I.e., earlier than R Gamliel.

      A different approach has the Babylonians and Greeks themselves getting their science from the Jews, the Jews thus being the first. It should be noted though, that later Talmudic science is fallible, so even if pre-Babylon the Jews knew science from Sinai or otherwise, they later lost it.

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    8. Sexagesimal (or "base 60 notation") is the use of 60 minutes in an hour, 60 seconds in a minute, or minutes and seconds in a degree. And the basis for measuring a circle in 360 = 6 * 60 degrees and our dividing an hour into 1080 = 18 * 60 chalaqim.

      It comes from the Babylonians not having fractions. So, in order to do math, it paid for their units to come in very divisible multiples. 12 hours in a day gave a natural way to talk about half a day (6 hours), a third (4 hours), a quarter (3 hours), etc...

      Sexagesimal is even better, as you get 30 min (1/2), 20 min (1/3), 15 min (1/4), 12 min (1/5), 10 min (1/6), 6 min (1/10)...

      On the other hand, it meant that they had little way to divide prime numbers (numbers only divisible by one and themselves: 2, 3, 5, 7, 11...) And so in their culture, prime numbers were unlucky.

      In Bavel, the tradition of a workweek was reinterpreted to be about resting on the 7th day because success was unlikely and whatever you made would be ill fated anyway.

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    9. @GP
      "independent of other sources"

      Um no, the whole point is that given the figure is identical the source is almost certainly the same. The fact that it is quoted first in Babylonian sources and uses the Babylonian numbering system indicates it is likely a Babylonian calculation. However even if it were not so there is no reason to assume it being divine given that other cultures made their own calculations of the same to similar degrees of accuracy (depending on the timing of when the calculation was made, possibly better accuracy).

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    10. I agree there is no reason to assume the figure is divine, in all cases. Iam skeptical of the Babylonian claim, though. The article linked in the post nowhere contained any clear statement on the lunar length, certainly nothing close to R. Gamliel's crystal - clear statement (which the post claims, without proof, is a later interpolation.) And as I said, goyim read things into the ancients just like Jews do. And there are so few men who can read Cuneiform to begin with, and so much depends upon interpretation, in a difficult mathematical area. If nothing else, I hope the naive and gullible have learned from the past two years that you can't believe everything you're told.

      GP

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  10. Is it true that the length of the molad (as calculated in Rosh HaShanah 25a, B.T.) emanated from the scholars of N'vukhadnetzar? No. Daniel was promoted above all the heathen scholars. According to Chazal, this happened in the year 421 BCE (Sefer Olam Rabbah). However, Daniel was a captive years earlier. Now, take into consideration the scholars R.A. Parker and W.H. Dubberstein, who made it evident that the heathen scholars got their calculations for the synodic month in the year 424 BCE. In other words, they definitely took it from us!

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    1. Just for the record, Daniel would have been taken into galut in about 597 BCE and thus there was no way he was still alive in 421 BCE.

      On the other hand, the Book of Daniel was probably written, or at least finally written, about 167 BCE.

      This doesn't necessarily challenge your point one way or another, but it's good to be precise as to facts.

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    2. Nachum, old news. You're following the Greeks & Josephus regarding the duration of the second temple. R Schwab, who you recently quoted,
      http://www.rationalistjudaism.com/2022/05/the-latest-conspiracy-theory.html?showComment=1653333125149#c7050499695006350717
      accommodated this and set Daniel earlier. (Not by the "166 odd years" of that comment but by precisely 168 years which is divisible by 7 and by 28, thus accommodating Shmita and Birchas Hachama.) (Later R Schwab recanted.)
      But Yitz is quoting Chazal. Before you dismiss them, you should mention them.

      A reason why R Schwab recanted is because he found sources that the Christians (I believe) tampered with the calendar to "confirm" their narrative. R Schwab thus became less impressed, and hence felt less challenged, by the Greek chronology.

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    3. He himself said he's quoting Chazal. I didn't see a need to acknowledge it, especially if I think that they were wrong.

      It kind of beggars belief that the "Christians" would somehow have been able to alter Persian records (which is what is at issue here, not Greek ones) many which weren't even discovered until a century or two ago.

      You need to do a little work to get to 168 when Chazal say the Churban was in 351, 352, or 353 BCE and history says it was in 586 or 587 BCE.

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    4. Oh, and there's no need to "accomodate" Shemita, which we no longer keep in the same cycle as Bayit Rishon (no Yovel since then) or Birkat HaChama, which was only set in the first place by Chazal, and then not even necessarily in a 28-year cycle.

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    5. Our Shemittah (derabbanan) was set to be at years evenly divided by 7. Very artificially pegged to Anno Mondi. However, what that means is that it would be 167 years, not 168. As we see from Seder Olam, in Anshei Keneses haGdolah's day, they counted the 6 days of creation as 1. We count it as zero. So it is more likely that the missing years is one less than a multiple of 7. Which might even be why we have a different year 1 than they used to.

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    6. Is there any contemporary evidence that counting from creation was used as early as the Anshei Knesset HaGedola?

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    7. I don't know about the time of the AKHG, but later they certainly used 'Minyan Shtaros'. (This is used to discredit the letter of Aristeas, which has the creation date. Why in the world wouln't it have the Minyan Shtaros or else the 'Shnas Hamelech'?)

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  11. Thank you Rabbi Slifkin for penning this post. I did a deep dive on this topic about six months ago, and felt very angry & deceived. 27 years ago, the lunar synodic proof from RH 25a was what made me accept the prevailing Orthodox narrative as ironclad. Over the years i have had other kiruv proof bubbles burst one by one, but when my nail-in-the-coffin proof vaporized, I am just continuing as orthoprax since i have a wife and kids, but I am furious at these well intentioned idiots who ultimately betrayed my trust.

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    1. Go ahead with the Orthopraxy, but WADR are your wife and kids better off than your nieces and nephews?

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    2. I'm sorry but I don't understand your fury. The people who gave you the proofs which you now don't accept did so because they absolutely believed them. No one was trying to pull the wool over your eyes. So there was no betrayal or deceipt. Ok, you feel you've intellectually moved on, but at the time you accepted arguments from people who genuinely thought they were true. What's wrong with that?

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    3. It's a shame you came to religion under what you now think (mistakenly) to be the false pretenses of how to interpret RH 25a. But understand how foolish this sounds, to make such trivialities the litmus test of a 4000 year old religion. This is what Chazal meant by קשים גרים לישראל כספחת. Today they would have said it about Ballei Teshuvah. (And in view of their characteristic excitability and attraction to anything new and shiny, it also includes professor Slifkin despite a religious upbringing.) The point it encapsulates is that people whose religion is not deep rooted cause problems. They don't have the depth or the same sense of responsibility of those who have been with the team for generations. They can't weather storms as well. They look to cut and run at the first sign of turbulence. Their attraction and devotion to the cause is superficial. When it's no longer attractive to them or something else comes along more attractive, they're gone. Not the ones you want on your team. That's exactly what chazal meant.

      Hard words, but true. Daniel, I hope you come to see the broader perspective.

      GP

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    4. OTOH Tosfos to Kidushin 71a sees fit to include the interpretation that Geirim are superior to born Jews in their observance of Mitzvos, and are therefore a ספחת in the sense that they create a standard that born Jews aren't living up to and are therefore judged more harshly.

      R Wolbe cites the Yalkut Mishlei

      ר' שמעון בן מנסיא אומר הרי הוא אומר (משלי פרק כז פסוק ז) נפש שבעה תבוס נופת זה תלמיד שלמד מתחלתו, ונפש רעבה כל מר מתוק זה תלמיד שלא למד מתחלתו.

      In other words BTs and Geirim outpace FFBs in their thirst for Torah. He says that they can find encouragement from this. Indeed, we know of FFB places that were invigorated by the the BTs who joined them.

      The Yalkut is saying, and experience confirms, is that FFBs tend to underdoing, while BTs and Geirim tend to overdoing. Whichever you are, you have a mixed blessing. And whichever you are, you have something to learn from the other one.

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  12. See https://skeptics.stackexchange.com/a/26927

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  13. One small question: Isn't it entirely possible to have certain astronomical facts very correct while being very wrong about others? Sailors were able to navigate and astronomers could predict solar eclipses even when people still believed the Earth was at the center of the universe. They may have had a wrong *basis* for their calculations, but they still did OK.

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  14. Similar points over here: talmudology.com/jeremybrownmdgmailcom/2021/11/2/rosh-hashanah-25-the-length-of-the-lunar-month

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  15. I think it is more important to create alternative approaches than it is to debunk the fallacious ones. Most people are satisfied with gimmicky prooftexts and for that purpose its fine; they were never after empiricism to begin with. Its the questioners that lurk the internet that need an alternative, and here it is.

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  16. This is a fascinating topic in general. A few points maybe worth noting:

    As mentioned by @micha berger above, the actual average lunation changes over time (due to the transfer of angular momentum from Earth to the Moon). This is a little bit of a complicated issue as you have two offsetting factors: 1 - the Moon drifts away from Earth meaning that it has a slightly *longer* orbital period (and thus the lunation period increases), but at the same time 2 - the Earth itself slows in rotation meaning that the length of a day (as measured in say atomic time) itself increases. Thus if you measure the month in fractions of an average Earth day it overall speeds up over time (shorter month length by c. 0.3 seconds per millennium, although it's not quite linear), but if you measure it in atomic seconds it slows down over time (c. 0.2 seconds per millennium; again not linear). In practice atomic time is a modern concept and therefore not really relevant for this discussion, therefore we can say in short that the average lunation period is falling (speeding up) by about 0.3 seconds per millennium.

    What has all of this got to do with the discussion at hand? While the Talmidic figure is currently a little too long, in the past this was not the case as months were slightly longer back then. There was a theoretical point in time when the Talmudic figure was exactly right (again this depends on how you define an "average" and how that changes over time). This will have been c. 2000 years ago (lots of rounding happening here). Prior to this the talmudic quoted figure will have been slightly too short and that difference will be larger the further back you go. Going back to the time of the Revelation to Moshe (2448) gives you a time when the figure will have been c. two thirds of a second too short. It would be somewhat strange that Moshe would receive a number significantly less accurate than what it would later become at the time it was codified in the Talmud (although on the other hand it is interesting that at the time Gamliel allegedly said it it was very very accurate indeed).

    More importantly, you can look at the calculated "molad" that we use to set the hebrew calendar and see where in the world that calculation gives an accurate local time for the mean lunar conjunction. As the length of the month in the calculation is slightly too long this point on the surface of earth drifts eastward over time. However going back more than a millennium or so the opposite was true and the point was drifting westward over time (as the calculation was using a slightly too *short* month). The furthest west this point has ever gotten over the past several millennium will have been c. 39 degrees east (of Greenwich) about two thousand years ago or so. Back in the time of Moshe it will have been significantly further west, maybe somewhere over India (and even further west at the hypothetical AM 0 year). Thus while the coincidence of the figure being very accurate at the time of Rabban Gamliel is indeed interesting it is at the same time interesting to note that our calender would never have been perfectly accurate in Israel.

    Finally very worth noting that the Babylonian / Chaldean figure quoted is not the only ancient calculation of average lunation length, there is a separate calculation done in ancient China (the best reference I could find to this was here: http://adsabs.harvard.edu/full/2002JHA....33...21C attributed to Liu Hong of 129-210 CE so after Gamliel but same era). The mean lunation they used was 29.5305422... days vs. the 29.53059414... so differing by c. 4 seconds per month. While the Chaldean figure quoted by the Talmud is quite a bit more accurate it does show that pretty accurate calculations were possible in ancient times.

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    1. Yoni2 -
      "Going back to the time of the Revelation to Moshe (2448) gives you a time when the figure will have been c. two thirds of a second too short. It would be somewhat strange that Moshe would receive a number significantly less accurate than what it would later become at the time it was codified in the Talmud (although on the other hand it is interesting that at the time Gamliel allegedly said it it was very very accurate indeed)."

      Might it be plausible to suggest that the Mesorah from Sinai to R"G, wasn't limited to the length of the Lunar month as stated by R"G, but rather the Mesorah was the orignial length of the Lunar Month and the factor to calculate how that will change over the days, weeks, months, years, centuries, millenia, etc?

      Of course, as RNS has repeatedly pointed out, the bigger concern is that R"G made his statement with regard to minimum lunar months, not mean lunar months.

      We might be able to answer RNS's quandary by proposing that since the length of the Lunar month is not a constant, perhaps it is plausible that at a certain point in history, the Minimum Lunar Month length (not the Mean length) was precisely as R"G described it, and perhaps that occurred at the time the Moon came into existence roughly 4.53 Billion years ago? perhaps this Gemara actually disproves the young earth theory??

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    2. @Jeffrey: My point was that it wouldn't be strange for Moshe to be given the accurate molad for a time when there would be no Sanhedrin and drift could accumulate. Our molad was close in R Gamliel's day, but closest in the 5th cent CE. when the current fixed calendar was established.

      Beyond "not strange", it would be an incredible coincidence.

      Regardless of whether Hashem provided us that measure by revelation to Moshe or by causing a fortuitous error when we or the Babylonians measured it (depending on who taught it to whom) .

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    3. The Mechilta https://www.sefaria.org/Mekhilta_d'Rabbi_Yishmael.12.2.2 explains "hachodesh hazeh lakhem -- this month shall be for you" using the general principle that "hazeh" means something was pointed to. So, the Mekhilta says that Hashem showed Moshe what a new moon looked like. But did Moshe really need Hashem to show him what a thin crescent on the west side of the moon looks like? Or was the revelation more complete, showing Moshe everything we would need -- including the molad?

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    4. @jeffrey

      1- does not sound plausible to me. As noted by RNS and throughout the comments, the figure is quoted by the Babylonians when it was not of as high degree of accuracy as it later was. Hence the exact number was clearly the thing being passed down with no adjustments.

      2 - your theory about the minimum lunar length having previously been the quoted molad interval, i'm pretty sure you are way off. The difference in lunar length back then will have been days, not hours.

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    5. Yoni2

      Your point that at a rate of 0.3 seconds per millenium, my 4.5 Billion years results in a delta of days rather than hours is well taken.

      However, you also said the change is "c. 0.3 seconds per millennium, although it's not quite linear." it's the "not quite linear" part of the statement which suggested to me that perhaps further back the delta might slow. you didn't provide exact equation, so I couldn't do the math.

      Nevertheless, presuming a more constant rate of 0.3 seconds per millenium, or 3,333 years per second (roughly 12,000,000 years per hour of change); you will hit 65 million years ago (when the huge asteroid that destroyed most life on the planet, including the dinosaurs, smashed into our planet) in less than 6 hours of lunar month length change.

      Could it be plausible, that such a cataclysmic (or similar) even impacted the position of the earth relative to the moon such that R"G's clear statement regarding the "minimum (not mean) lunar month length" is still evidence that R"G had supernatural knowledge of a very ancient earth? and not only that, but R"G also knew, (utilizing super natural knowledge) precisely how long ago that asteroid hit? I think that is certainly within the realm of possibility using the figures provided.

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  17. So ironic, talking about undermining Torah and Chazal R'L....
    The person who has perhaps undermined Chazal, the most in our generation is probably Rabbi Dr Slifkin.

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    1. Sounds like you've done quite a survey. If Slifkin is #1 who is #2 through #5? I think you exaggerate his influence and the alleged undermining,

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  18. "Instead, present the extraordinary history of the Jewish People, culminating in our miraculous return to our homeland, along with the incredible meaningfulness and value of a Torah-observant lifestyle"

    This is great for people who are already somewhat committed. Have you had success using this argument/presentation to convince people to become religious?
    -TT

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  19. Anon 5:38 AM,

    What’s so terrible about undermining CHAZAL? Isn’t it CHAZAL that has erased women from public discourse, eliminating their likeness and even names from magazines and invitations? And surreal prohibitions on unfiltered tap water or freshly rinsed vegetables and fruits? And young children being denied a secular education and grown men refusing to work to support their families, etc., etc.
    There has not been enough undermining of CHAZAL to bring Chareidiland to their senses.

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    1. Chazal refers to "The Rabbis" ie. the Rabbis of the Talmudic period.
      YA

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    2. (חכמינו זכרונם לברכה
      True‎. But I was referring to them in modern day terms as in The Daas Torah dolts. Our חכמינו זכרונם לברכה would never have exacted such insane prohibitions as I had mentioned.

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  20. Pirkei D'Rabbi Eliezer has some good info in it on this

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  21. A very good article about Chazal and NASA and the renewal of the moon. Interesting that the Greeks and Babylonians had the same number.

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  22. And who said that Jews learnt it from Babylonians but not other way around? It is inconceivable that Babylonians could measure the lunar month with such accuracy without modern tools available to NASA.

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    1. It's really silly to not believe something that is right in your face. Many cultures made the same calculation, all within a similar degree of accuracy, thousands of years before NASA.

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    2. Read the articleJune 2, 2022 at 7:04 PM

      Did you read the article? The rabbi literally explained why the Jews got it from the Babylonians.

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    3. RNS only showed the Babylonians got it. Melakhim II 24-25 tells us they drafted our intelligensia and nobility into their royal court . There is no reason to assume we got it from them, if they expected us to teach them things.

      As for it requiring modern tools, the post does say:
      "You don't actually need supernatural sources of knowledge to come up with this figure. The Babylonians were simply very meticulous astronomers. By measuring the duration between eclipses, one can figure out the mean length of the lunar month. (See here for an extremely technical discussion.)"

      Yoni2 responded to an earlier comment of mine (and I didn't do the math to doubt him) that it wouldn't even require remarkable time keeping to get that accuracy.
      ____

      To me, the big deal is that the molad interval we use was less accurate back in the days of Galus Bavel than it was in the days of Rabbi Hillel's Sanhedrin near the end of the amoraim, when the calendar was established. Regardless of how that number was obtained, Hashem clearly let a measure emerge that was tuned for our purposes.

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