Scientific Content in Jewish Sources
Professor N. S. Kopeika
about the author
Natan (Norman) Kopeika was born in Baltimore, MD, and
raised in Philadelphia, PA. He obtained BSc, MSc, and PhD
degrees in electrical engineering from the University of
Pennsylvania, specializing in electro-optics. While preparing for his doctorate, he studied privately towards rabbinic
ordination (Yoreh Yoreh), finishing requirements for both
before coming on ạliyah with his family in 1972.
He joined Ben-Gurion University of the Negev in 1973
and reached the rank of professor in 1987. He has chaired both the Departments of
Electrical and Computer Engineering (1989–92) and Electro-optical Engineering
(1998–2005). He is the author of about 190 papers in international professional
journals, about 150 conference papers, and two books on electro-optics. He has
supervised about fifty graduate student dissertations. His areas of specialization include imaging theory and systems, atmospheric optics, effects of ambient environment on semiconductor device surface states and device properties,
interactions of electromagnetic waves with plasma, and thermal and millimeter
wave imaging. In 1999, he and his former student and present colleague Professor
Shlomi Arnon were recipients of the Thomson Prize from the IEE (UK). Since
1994 Professor Kopeika is the incumbent of the Reuven and Frances Feinberg
Chair in Electro-optics at BGU. He has been a Fellow of SPIE since 2000.
He married Miriam Sirota in 1966. They have three children and eight grandchildren, with two of the families living in Beersheva and one in Otniel.
For the past several years, he has served as spiritual leader of the historic
Hadassah Synagogue in downtown Beersheva, founded and named in 1948 after
the medical convoy massacred on Mount Scopus.
Presented at the Moshiach and Science Conference of the RYAL Institute in Beersheva, 14
Iyar 5773.
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86 B ’ OR HA’ TOR AH 23 5775 (2014–2015)
abstract
The eight examples of science in Jewish sources presented below support the
viewpoint of Naħmanides concerning the relationship of science and Torah as
described in his introduction to Genesis. Discussions include a surface physics
explanation for the concepts involved in koshering utensils, as well as a novel
explanation for a discussion in Talmud tractate Pesaħim concerning the size of
the Earth. Examples such as the evaporation-condensation cycle, weather patterns, and sea currents derive from the literal meaning of Biblical verses; while
examples such as sex determination reflect Talmudic understandings of Torah
verses that go beyond the literal meaning. There is no implication here that
the Talmud Sages necessarily understood the scientific aspects of Torah, only
that they transmitted them from generation to generation as Oral Tradition.
introduction
T
he overlap between science and Torah is still the subject of a great
deal of discussion. (See, for example, Aviezer 1990; Bodenheimer
2012–2013.) In these areas of overlap, one would expect mutual compatibility, as two different approaches to the truth. In this paper I shall
present eight examples of science in the Torah, ranging from concepts
known in the ancient world to concepts discovered or developed in
the modern age. Torah refers not only to the Five Books of Moses
and Scripture, but also to the Oral Tradition. The Talmud tells us
that Scripture and the Oral Law were given at Sinai and complement
each other (Talmud Brakhot 5a on Exodus 24:12).With regard to the
Talmud, Shmuel Ha’Nagid distinguishes between halakhah and aggadah. The former, he holds, is law and must be accepted totally; with
regard to the latter, we are obligated to accept only that which is plausible (see Mevo Ha’Talmud for definitions of aggadetah and hilkhatah,
found in most Babylonian editions of the Talmud between tractates
Brakhot and Shabbat). The Talmudic examples here relate to halakhic
issues. Some present straightforward literal meanings as understood
by classical Biblical commentators.
The general approach adopted here is that of Naħmanides, described
in his introduction to the book of Genesis. After discussing the concept
of Torah from Sinai, Naħmanides suggests that the Creation and the
forces of nature were all described or given to Moses and written in the
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Torah in some form either explicitly, or through hints, or numerology,
or in the forms of the letters, or the “crowns” (tagim) above letters.
Naħmanides quotes the description in the Talmud Rosh Hashanah 21b
of the fifty categories (sheạrim) of knowledge created in the world, of
which forty-nine were given to Moses. Naħmanides suggests that the
creation of the universe therefore involved fifty categories of knowledge.
He suggests as possible examples materials or minerals, vegetation,
animals, and mankind. He further suggests that the category not given
to Moses involved knowledge of the Creator, which cannot be given to
those whom He created. The numbers involved, fifty and forty-nine, are
hinted at in the Torah, for example, with regard to the counting of the
ọmer and the counting of years until the Jubilee. Naħmanides maintains
that King Solomon’s knowledge of the strengths and medicinal properties of herbs and his ability to communicate with birds and animals
were all obtained from the Torah.
Below are eight specific examples which can illustrate Naħmanides’
view that science exists in the Torah in the form of the above she’ạrim.
The examples involve concepts rather than a “handbook” of numerical
values. (The Torah is not, of course, a handbook of science.) To these
can be added examples such as the shape of the Earth (Jerusalem
Talmud, Ạvodah Zarah, Chap. 3, halakhah 1, and Isaiah 40:22) and the
Jewish calendar, which have been discussed elsewhere. Naħmanides’
concept of conversion of energy and mass also has been discussed
elsewhere.
examples
1. the size of the earth
A discussion is held in the Talmud Pesaħim 94a concerning the distance a person can walk in one day. The discussion continues with a
statement by Rava that the Earth is 6,000 parsah, and the width of
Heaven is 1,000 parsah. The Talmud says that the former is tradition,
and the latter is reasoning.
A parsah is equal to four mil. A mil is approximately one kilometer,
so that the distance considered is approximately 24,000 kilometers. The
Talmud then quotes Rabbi Yehudah, who says that a normal walking
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distance is forty mil during the day, plus four mil from dawn to sunrise,
and four mil from sunset to the coming out of the stars. The Talmud
infers from this that the time from dawn to sunrise and from sunset
to the coming out of the stars are each one tenth of the duration of
a day (a ratio of four to forty mil), equal to 1.2 hours or 72 minutes,
assuming a twelve-hour day as at the spring and autumnal equinoxes
(tikufat Nisan and tikufat Tishrei). As the discussion continues, eventually the Talmud refutes separately each of Rava’s statements, with the
conclusion that both statements are refuted. However, Rava’s tradition
of 6,000 parsah or 24,000 kilometers can be explained to be in accord
with scientific measurement of the circumference of the Earth. The
explanation is that the 24,000 kilometers represent the arc length of
that part of the Earth in which there is sunlight. This arc length must
be divided into two components — one of direct illumination and one
of indirect illumination. The former represents those areas in which the
sun can be seen directly. Here the time of day is between sunrise and
sunset. Indirect solar illumination is in areas which are in transition
from night to day (between dawn and sunrise) and from day to night
(between sunset and darkness). Rabbi Yehudah indicates that the arc
of each transition region is one tenth of that over which there is direct
sunlight and, according to Rava’s tradition, the sum of all three arcs is
approximately 24,000 kilometers. This means the arc over which there
is direct sunlight, which is half the circumference of the Earth, is 20,000
kilometers. The two transition arcs are then one tenth of that, or 2,000
kilometers each, yielding an arc of 24,000 kilometers over which there
is some sort of sunlight. The meter is defined historically such that
the Earth’s average circumference is 40,000 kilometers. However, the
purpose of the discussion in the Talmud is not to teach us the circumference of the Earth.1
1. Editor’s note: The great Talmudic scholar and philosopher, the Maharal (1520–
1609 C.E.) makes a fundamental point regarding this particular Talmudic source
and others: “Do not think that this measure of the world is a physical measure,
for you must know that the Rabbis did not consider such things at all, because
matters that do not pertain to the essence of the world and its essential truth
they did not discuss at all… This measure of 6,000 given by the Sages is only an
abstraction of essence and spirituality, not a material measure.” Be’er Ha’Golah,
part 6, chap. 4. Other rabbinical sources make similar comments. However, the
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The significance of the position of Rabbi Yehudah concerning the
transition time from day to night and night to day being one tenth
of the day at the equinox (tikufat Nisan and tikufat Tishrei) is demonstrated by the Tosafot, who ruled that the halakhah is according
to Rabbi Yehudah. This is the ruling accepted in the Shulħan Ạrukh,
Oraħ Ħayyim 261:2, although there is a difference of opinion between
the Tosafot and the Vilna Gaon as to how these 1.2 temporal hours are
composed. This halakhic statement of Rabbi Yehudah is basic to my
explanation above of the circumference of the Earth in accordance
with Rava’s tradition.
2. treifah
The prohibition given in Exodus 22:30 against eating treifah refers to
animals that would die within twelve months because of an internal
or external blemish conforming to the definitions of treifah (Talmud
Ħulin 42a, 57b-58a). There is some question as to whether the implication is a literal twelve months (Pri Ħadash on Shulħan Ạrukh,
Yoreh Deạh 57:18), or thirteen months for a leap year (Siftei Kohen
on Shulħan Ạrukh, Yoreh Deạh 57:18), or 365 days (solar year, Pitħei
Tshuvah on Shulħan Ạrukh, Yoreh Deạh 57:18). The Talmudic discussion implies that it is essential for the animal in question to be
capable of surviving the various changes in seasonal conditions such
as heat and cold that occur during a normal year in order for it to not
be considered treifah (Talmud Ħulin 57b-58a). Consistent with the
concept that the kashrut of permissible animals is associated with life,
and treifah with death (ibid., based on Leviticus 11:2), if the animal
in question is female then the ability to become pregnant is sufficient
for the animal not to be considered treifah even before the “twelve
month” trial period has passed (Siftei Kohen on Shulħan Ạrukh Yoreh
Deạh 57:18). Such criteria for determining whether or not an animal is
treifah can be applied only in cases of doubt. (See Ạrukh Ha’Shulħan,
Yoreh Deạh 57:78 for a list of examples.) If there is a conflict of opinion, the clear halakhic criteria take precedence over “twelve month”
author is suggesting that Rava’s tradition, although rejected by the Talmud itself,
can be explained in accordance with modern knowledge.
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or pregnancy criteria (Siftei Kohen on Shulħan Ạrukh, Yoreh Deạh
57:18). Even if medical opinion is that under certain conditions a nontreifah animal will not survive for the “twelve month” period, we do not
add such conditions to those for which an animal is considered treifah
(Maimonides, Mishneh Torah, Sheħitah 10:12–13). Similarly, even if
modern medical opinion is that some or all of the treifot listed by the
Talmud Sages are conditions under which animals can live rather than
die, we still do not change the list of treifot (ibid.). We neither add
nor detract from the halakhic list of treifot, no matter what medical
opinion may be (Meiri on Talmud Ħulin 57b-58a). The association
of death with treifah does not necessarily apply for all animals with a
given treifah condition (Siftei Kohen on Shulħan Ạrukh, Yoreh Deạh
57:18). It is recognized that some animals considered treifah can survive
for “twelve months” (ibid.).
Nevertheless, the “twelve month” criterion supports the connection
of the laws of treifot to the above concepts of life and death (Levin and
Boyden, 1969).
3. kirchhoff’s law and conservation of energy
Kirchhoff ’s Law of Thermal Radiation (1860) states that the radiant
emission and the absorption of a material body in thermodynamic
equilibrium are equal (Siegel and Howell, 1983). This stems from
conservation of energy and implies that the radiant energy emitted
by the surface of a body is equal to that absorbed by it when the body
is in thermodynamic equilibrium with its surroundings. If an object
is heated, it absorbs energy and becomes hot. If the heating process
is stopped, that object does not remain hotter than its surroundings
but cools until it reaches thermodynamic equilibrium with the surroundings. If the ambient temperature remains unchanged, the energy
gained by the object equals the energy lost (ibid.). Such surface effects
are analogous to the Talmudic concept of ke’volọ kakh polto (Talmud
Pesaħim 30a, 74a), which is the basis of koshering utensils which have
absorbed a forbidden substance. The utensil must be heated to at least
that temperature at which the forbidden ingredient was absorbed in
order for that ingredient to be released or “emitted.” By then immersing
the object in cold water, the forbidden ingredient is removed.
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The koshering process can be understood physically from surface
physics as follows. Molecules inside a given material usually have
identical molecules around them, and chemical bonds can be formed
between them. However, molecules on the surface do not have identical
molecules in the outward direction with which to form bonds, since the
outward direction involves a different material — usually air. Hence,
the surface molecules usually form weaker bonds with ambient external
molecules such as oxygen, nitrogen, water vapor, and so on, since there
are no identical molecules in the outward direction with which to form
bonds. When an object is heated, such bonds can be broken, and if
a forbidden ingredient is located on the surface, it can form bonds
with the surface atoms of the utensil. The forbidden ingredient is thus
adsorbed onto the surface.2 To kosher the utensil, its surface must be
heated to at least that temperature at which the forbidden ingredient
was adsorbed in order for such bonds to be broken and the forbidden
ingredient to be released. By immersing the utensil in cold water, the
forbidden ingredient is removed from the surface so that it cannot be
re-adsorbed elsewhere in the utensil.
The koshering process can be explained by analogy to the concepts
which comprise Kirchhoff ’s Law. As in the previous examples, this
does not mean that the Talmud Sages knew infrared or surface physics, but rather that analogous concepts are contained in the Torah in
the form of ke’volọ kakh polto (ibid.) rather than Kirchhoff ’s Law. The
latter deals with absorption and emission of radiant energy; the former
can be explained in terms of adsorption and emission of “forbidden”
substances which also depend on energy.
4. gender determination
Talmud Niddah 31b states that if a woman reaches satisfaction (mazraạt)
first, if she conceives the child will be male; if her male partner reaches
2. Editor’s note: Adsorption is the adhesion of atoms, ions or molecules onto a
material surface, from a gas, liquid, or dissolved solid. This process creates a film
of the adsorbed substance on the surface of the material, to which the author’s
explanation applies. In contrast, absorption is a process in which the external
substance penetrates into the bulk of the material, to which the author’s explanation does not properly apply.
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satisfaction first, the child if conceived will be female. This is based
on Leviticus 12:2 in which the words ki tazriạ appear to be superfluous. This particular Talmudic concept is now known as an important
factor in gender determination (Rorvik and Shettles, 1970; and
Shettles and Rorvik, 2006). The biological explanation is the following. Y chromosome sperm, which produce males, are of different
physiological structure than X chromosome sperm, which produce
females. The male-producing sperm have a smaller “head” but larger
tail, thus making them less rugged with a shorter lifetime, but faster
than the female-producing sperm. If the female partner reaches satisfaction first, her medium is more favorable in alkalinity to the sperm
and the faster male-producing sperm with their longer tails are more
likely to reach the egg first. However, if it is the male partner who
reaches satisfaction first, the medium in which the sperm have to travel
is more acidic, which is detrimental to the less rugged male-producing
sperm, thus making it more likely that the female-producing sperm will
reach the egg first. In the latter case, a girl child is more likely to result.
Reliability of this phenomenon is about 75–90 percent. (Shettles 1970;
and Shettles and Rorvik 2011). It is not infallible because of statistical
variations, e.g., some males have sperm that is more abundantly male
or female, rather than half and half. (The author has been informed by
physicians that they actually use this insight of the Talmud in advising
their patients.) This medical discovery had to wait until the 1960s when
discovery of the different physiological features of the X and Y chromosome sperm became better understood. Differing lifetimes of both
types of sperm further limit reliability. This method of choosing the sex
of babies, known as the Shettles method, is also therefore dependent
on the accuracy of prediction of ovulation time.
The Whelan method has also been suggested as a way to choose the
gender of babies. It contradicts the Shettles method in many aspects,
especially the timing of copulation with regard to ovulation. However,
reliability is only about 56–68 percent, which is much closer to the
natural 50 percent probability range (Whittle and Rodeck, 2006).
Again, the Torah is not a biology textbook. Nevertheless, this is an
example of a law of nature clearly described in the Torah.
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5. weather patterns
Ecclesiastes 1:6 tells us that winds blow in cyclonic patterns: “The wind
blows to the south and turns to the north; round and round it goes, ever
returning on its course.” Although today cyclonic wind patterns are
seen easily in satellite photos, they were not confirmed until Benjamin
Franklin discovered them about 200 years ago. This understanding is
the literal meaning of this verse according to the major classical commentators Rashi, Ibn Ẹzra, and Radak. It is attributed in the Talmud
Bava Batra 25b to Rabbi Yehoshuạ and in Midrash Yalkut Shimọni to
Rabbi Eliẹzer, both of whom consider how wind directions change in
a cyclonic pattern according to the position of the sun in the spherical
envelope of the sky surrounding the world (Rabbeinu Ħananel on
Talmud Bava Batra 25b).
6. suspension of the earth in space
An expression describing G-d’s majesty used in Rosh Hashanah hymns
extolling the Creation of the universe, is toleh erets ạl belimah. This
is from Job 26:7 where, according to commentators such as Rashi,
Metsudat Zion, and Ibn Ẹzra, belimah is composed of the two words
beli mah, which together mean “nothing,” i.e., G-d suspends (toleh) the
Earth on nothing” (Yalkut Shimọni 913). Commentaries on the Rosh
Hashanah prayer book explain belimah similarly. Although homiletical teachings have been suggested, the literal meaning (according to
Metsudat David and Metsudat Zion) is that the Earth is suspended in
space with nothing to support it. This is the description given by the
traditional Targum translation. The verse describes how, indeed, the
Earth appears in space from afar. In the Midrash, Rabbi Abahu uses the
word belimah (beli mah) to refer to G-d Who conceals Himself (k’eilu
aino) while supporting the world.
7. sea currents
In 1839 Matthew Maury noticed that Psalm 8:9 describes paths of the
sea (orħot yamim). Up to that time sailors had not yet charted ocean
currents nor used them to navigate. Maury understood the potential
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94 B ’ OR HA’ TOR AH 23 5775 (2014–2015)
advantages of such currents for navigation. His landmark book The
Physical Geography of the Sea, published in 1855, is considered a milestone in the beginning of oceanography. He understood the significance of the phrase “paths of the sea” literally, and then looked to find
ocean currents and streams. His understanding of this verse is actually
the literal meaning according to the Targum, Ibn Ẹzra, Metsudat David,
and Radak, all of whom specifically describe man as building ships
which pass through paths of the sea.
8. the evaporation-condensation cycle
Ecclesiastes 1:7 describes how rivers run into the sea but the sea is never
full. Classical Biblical commentators on this verse explain the reason as
being the evaporation-condensation cycle, and connect it to Amos 5:8,
in which G-d is described as “calling the water of the sea and pouring it
upon the face of the Earth.” Ibn Ẹzra, Radak, and Metsudat David agree
that evaporation is the literal meaning of these verses. The commentaries distinguish between saltwater and sweet water, i.e., even over the
sea, water is evaporated (“called”), but only sweet water forms clouds.
Actually this idea comes from the midrashim in Ecclesiastes Rabati 1:13
and Yalkut Shimọni 967, based on a discussion reported between Rabbi
Yehoshuạ and Rabbi Eliẹzer. The evaporation-condensation cycle is
also described by the Targum on Genesis 1:2.
conclusion
These eight examples of science in the Torah can be understood to support the view of Naħmanides that the Creation and the forces of nature
were all described or given to Moses and written in the Torah either
explicitly or implicitly. The Torah, of course, is not a science textbook.
In this regard, it is interesting to note that Rabbi Yehudah Ha’Nasi
did not hesitate to admit in a discussion on a certain scientific topic
that the wise men of the nations of the world are correct and those of
Israel incorrect (Talmud Pesaħim 94b). Furthermore, the fact that certain natural phenomena are described clearly in the Talmud does not
mean that the Talmud Sages understood their scientific implications,
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SCIENTIFIC CONTENT IN JEWISH SOURCES 95
but rather that these teachings were transferred from generation to
generation as part of our Oral Tradition.
references
Aviezer, N. 1990. In the Beginning. Brooklyn, NY: Ktav.
Bodenheimer, J.S. 2012–2013. “Our Sages’ Knowledge of Nature.” B’Or
HaTorah. vol. 22, pp. 125–136.
Kopeika, N.S. 1998. A System Engineering Approach to Imaging. Bellingham,
WA: SPIE Optical Engineering Press, pp. 135–137.
Levin, S.I., and E.A. Boyden. 1969. The Kosher Code of the Orthodox Jew.
NewYork: Hermon Press.
Rorvik, D.M., and L.B. Shettles. 1970. Your Baby’s Sex: Now You Can Choose.
New York: Dodd, Mead and Co.
Shettles, L.B. 1970. “Factors Influencing Sex Ratios.” Intl. J. Gynecology and
Obstetrics. Sep 1970, vol. 8, no. 5, pp. 643–647.
Shettles, L.B., and D.M. Rorvik. 1970. How to Choose the Sex of Your Baby.
New York: Broadway Books.
Siegel, R., and J.R. Howell.1983. Thermal Radiation Heat Transfer. 2nd edition. New York: Hemisphere.
Whittle, M.J., and C.H. Rodeck. 2006. How to Choose the Sex of Your Baby:
The Method Best Supported by Scientific Evidence. New York: Random
House.
Photo by Zev Rothkoff,
copyright ©.
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