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In Sepher M'lakhim we read how different measurement was taken. I wonder if this passage (Ⅰ M'lakhim 7:23) is describing an approximation of PI (3.1415...), or was this one of the hidden miracles?

וַיַּעַשׂ אֶת־הַיָּם מוּצָק עֶשֶׂר בָּאַמָּה מִשְּׂפָתֹו עַד־שְׂפָתֹו עָגֹל ׀ סָבִיב וְחָמֵשׁ בָּאַמָּה קֹומָתֹו [וּקְוֵה כ] (וְקָו ק) שְׁלֹשִׁים בָּאַמָּה יָסֹב אֹתֹו סָבִיב׃

Now he made the sea of cast metal ten cubits from brim to brim, circular in form, and its height was five cubits, and thirty cubits in circumference.

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can you define what you mean "one of the hidden miracles"? are you saying that it was a miracle that it was only 30 cubits, instead of the true value it should have been mathematically? –  Menachem Jun 6 '12 at 22:48
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I'm no believer in biblical literacy, but I've never seen the problem here. It doesn't say "10 cubits to infinity decimal places", it says "5, 10 and 30 cubits" That, to me, suggests that I probably rounded up from nine and a half -- why is that a problem? –  Jack V. Jun 12 '12 at 14:30
    
Thank you all for taking your time answering my questions. It is greatly appreciated. –  Millthorn Jun 17 '12 at 15:40
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Inner diameter; outer circumference? Or a curved in lip on the bowl with the circumference measured around the middle of the bowl, and the diameter across the top? Frankly, I've never seen the problem here. –  TRiG Jul 17 '12 at 18:05
    
Related: judaism.stackexchange.com/q/18903. –  msh210 Sep 4 '12 at 3:32

5 Answers 5

up vote 13 down vote accepted

It's approximating π, as is clear from the g'mara (Eruvin 14:1).

The problem is that that g'mara seems to be saying that it's a pretty precise approximation, and we know it's not. (Tosafos there raise this question and offer no answer.)

But to answer your question, whether it's an approximation of π or a miracle, it's the former.

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Thank you very much. I had hope for a definite answer. I'm satisfied to know that is is non. I'm satisfied with the explanation you gave. I hope that I can learn form g'mara my self some day. –  Millthorn Jun 6 '12 at 16:41
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To your question, whether the verse is approximating π or describing (no pun intended) a miracle, I think there is a definite answer: it's approximating π. –  msh210 Jun 6 '12 at 18:46
    
IIRC, one of the other tosafos, (Tosafos HaRosh, I think, but I can't find a copy online) rereads the gemara so that it makes more sense. I don't really remember how, though. –  jake Jun 6 '12 at 19:32

Wikipedia has a set of answers in their article on Approximations of pi. That links to a terrific article on rabbinic approximations of π by Boaz Tsaban and David Garber. Tsaban and Garber summarize as follows (pp. 10-11):

  1. The rational-religious approach of Maimonides holds that, since we cannot know the exact values, the Bible tells us that we do not have to worry about this and that is suffices to use the value 3.
  2. The mystical approach of [Matityahu Hacohen] Munk contends that 3 was indeed the ration of the circumference to the diameter in King Solomon's temple: This value is used in order to bridge the gap between our world and the "world of truth." For the sake of consistence, the halachic conditions are applied to the suitable regular polygons.
  3. The practical approach of R' Shimon Ben Tsemah [who learns from other places in Talmud that they used a more precise version of π] asserts the the rough approximations are used when teaching the students, but, when it comes to practice, the calculations are to be done by the experts.

So to answer your question, if you hold by Munk (I don't know who he is), then it's a miracle. If you hold by Rambam or R' Shimon ben Tsemah, it's an approximation

((Aside: two different psaks come out of this for practical reasons like sukkot - either you use the best mathematical approximation (R' Shimon ben Tsemah) or you use 3 (Rambam and Munk). In order to use 3 as π, you can just measure the perimeter of the interior inscribed regular hexagon.))

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Rabbi Max Munk "three geometry problems in tanach and talmud" (Hebrew), SINAI, 51: 218-227 (Harav Kook Institution, 5722) -- one of the sources used in books.google.co.cr/… -- looks like it's the same –  Menachem Jun 6 '12 at 23:17

The GR"A points out the following:

The word circumference (kav) is spelled קוה but pronounced קו. The gematria of the former is 111 and the latter is 106. The ratio of 111 to 106, multiplied by the approximation of 3, gives you:

(111 / 106) * 3 = 3.1415

Perhaps pi to five digits is a better approximation than 3?

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So you're taking the approximation side, not the miracle side. –  Double AA Jun 6 '12 at 19:06
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At what point is pi ever not an approximation? I think five places is pretty good. –  yoel Jun 6 '12 at 19:08
    
Indeed pi is a transcendental number. I'm only pointing out how you try to answer the question, because it wasn't very clear from your post. –  Double AA Jun 6 '12 at 19:10
    
I plead ignore: why do you take the ratio? And then why use the ratio to scale the approximation? Is there any methodology for this? And is there any suggestion that the value 3.1415 should be used in place of 3? Where does the Gra say this? Does he explain it? –  Curiouser Jun 6 '12 at 19:23
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@Curiouser, Early authorities had already proposed that the reason the "ה" is not extant in the kri is to hint to the fact that the measurement is in fact an approximation and is actually "missing" some length. The Gr"a is merely showing that there is a neat remez that can show how the number was approximated, that is the approximation is essentially a scaling by the ratio of the kri with the ksiv. There is no "methodology". If it would have been easier to hint to e.g. the difference instead of the scaling factor, perhaps it would have. –  jake Jun 6 '12 at 19:48

I think that the point is being missed here.

There are not that many places where there is a difference between the written word (k'siv) and the way the word is pronounced (kri). This is especially true where the written word would be pronounced the same way. The reason is generally that neither is quite correct. The "real" word should be some combination.

In this case, the gematria of the written word קוה is 111, while the gematria of the spoken word קו is 106. As the Gra shows, this provides a value of 3.1415.

Everyone seems to be impressed that Archimedes placed pi between 3 1/7 and 3 10/71 around 300 BCE, but that is between 3.1408 and 3.1429. The book of Kings was written about 600 BCE. Mathematics was not advance enough at this time to any person to provide this accuracy. It seems to me to less credulous to believe that there is a divine aspect than to say that it is a coincidence.

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Nice false dichotomy. –  Double AA Jul 17 '13 at 21:00
    
This dichotomy is what I am presented with in discussion with those who do not accept Torah. They tend to attribute most things to coincidences. Your alternative explanation is....? –  Steven Schulman Jul 17 '13 at 21:49
    
@StevenSchulman The problem with this answer is that it seems to go against the Gemara. –  Shmuel Brin Jul 17 '13 at 22:44
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Hi @StevenSchulman and welcome to mi.yodeya! The idea that the true meaning of words with a different k'ri than k'siv is an interesting one. Does it have a written source? –  WAF Jul 18 '13 at 14:34
    
How does the Gr"a get 3.1315 from 111 and 106? Please reply with @Daniel in the comment so I get notified. –  Daniel Jul 18 '13 at 18:38

There is a very, very full and wonderful essay on this topic (in English, translated from the Ruusian original) which can be found here, but I will quote two paragraphs which will significantly add to what has been discussed here already:

It appears to me that the correction קו/קוה (qava/qav) has not merely numerical meaning. The word קוה (qava) is feminine (in Hebrew the feminine words almost always end with ה) while קו (qav) is masculine. The way the word is spelled is called "masoret"-מסורת and is feminine, the way it is pronounced is called "mickra"- מקרא and is masculine. On the other side, in the pair circle-diameter, the circle represents a feminine, material notion (e.g. the mother Earth) while the straight line represents the masculine, spiritual notion (e.g. the rain that fertilizes the earth). Hence the word קוה (qava) is related to the circle while קו (qav) to the diameter. With this correspondence the verse 7:23 reads "קו (qav) ten cubits from the one brim to the other … and a קוה (qava) of thirty cubits did circle it round about". Thus the ratio of a circle to diameter becomes (30xqava)/(10xqav)=333/106.

Notice that that all objects in the tabernacle where straight. May be this is the reason why Rambam draw the Menorah with straight branches? If in the "heavens", in the spiritual world, there are no curved lines, the circle is perhaps represented there by a polygon. In case of the perimeter of the circle, the hexagon could serve as a model. In case of the area, the dodecagon could be the model. In the first case the perimeter is equal 2∙3∙radius of the surrounding circle; in the second case the area equals 3∙square of the radius, as if π=3. That is why the Sages considered the equality π=3 not as an acceptable approximation but as a reflection of a certain spiritual truth.

There is a lot more material there and it is well worth a look, especially if you are mathematically inclined.

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I think we already have two such answers –  Shmuel Brin Nov 21 '13 at 7:12
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@ShmuelBrin - Read it again. –  user4523 Oct 7 at 8:31

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