And when Jacob made an end of charging his sons, he gathered up his feet into the bed, and expired, and was gathered unto his people. And Joseph fell upon his father’s face, and wept upon him, and kissed him. And Joseph commanded his servants the physicians to embalm his father. And the physicians embalmed Israel. . . . And his sons carried him into the land of Canaan, and buried him in the cave of the field of Machpelah, which Abraham bought with the field, for a possession of a burying-place, of Ephron the Hittite, in front of Mamre. (Genesis 49:33–50:13)
Rabbi Yitzchak said to Rav Nachman: “So said Rabbi Yochanan: Our father Jacob did not die.” Asked Rav Nachman: “Was it for no reason that the eulogizers eulogized, the embalmers embalmed and the buriers buried?” Replied Rabbi Yitzchak: “I am only citing a verse. It is written (Jeremiah 30:10): ‘And you, my servant Jacob, fear not, says the Eternal, and do not tremble, O Israel. For behold, I shall save you from afar, and your progeny from the land of their captivity.’ The verse equates Jacob with his progeny: just as his progeny are alive, he too is alive.” (Talmud, Taanit 5b)
Did Jacob die or not? Is he alive or not? The Torah seems to say that he died; It clearly says he was embalmed, mourned by his children, and buried in the Cave of Machpelah in Hebron. The Talmudic sage, Rabbi Yochanan, states that Jacob did not die—he is alive just as his progeny are alive. This Talmudic statement can be interpreted in different ways. Some Talmudic commentaries say that the expression “Jacob did not die” is metaphoric, in that it suggests that Jacob continues to live (metaphorically, not physically) in his children in the sense that his legacy continues to live so long as his children follow his path. Others say that there is no metaphor here—the comparison is literal. Just as Jacob’s children are physically alive, so too is Jacob physically alive. The third explanation offered by Shelah suggests that Jacob had two aspects to his personality—one signified by his name Israel, and the other by his name Jacob. Shelah states that whereas Israel died, Jacob did not and continues to live.
These three explanations seem to correspond with three models of physical reality—classical physics, the Copenhagen interpretation of quantum mechanics, and the many-worlds interpretation of quantum mechanics.
The first interpretation is based on the question posed by Rav Nachman, “Was it for no reason that the eulogizers eulogized, the embalmers embalmed and the buriers buried?” In other words, Rav Nachman asserts a binary choice—Jacob is either alive or not. If Jacob is alive, how can that possibility be squared with the Torah narrative describing Jacob’s death, embalmment, and burial? Following this binary choice, we must interpret the answer of Rav Yitzchak that Jacob is alive just as his progeny are alive metaphorically—Jacob really did die, but he lives on in his children. This view is emblematic of classical (Newtonian) physics, where a system can only be in one state at a time; for example, a top can rotate either clockwise or counterclockwise, but not both at the same time.
According to the second interpretation, the words of Rav Yitzchak are to be taken literally—just as Jacob’s children are now physically alive, so too is Jacob now physically alive. This view appears to starkly contradict the Torah verses that describe Jacob’s death, embalmment, and burial. The only way to reconcile these two positions is to say that both are true, that is, that Jacob is both dead (as the Torah says) and alive (as the Talmud says) at the same time. This seems absurd from the point of view of classical physics and what we consider common sense, but it makes perfect sense from the point of view of quantum mechanics. As we have discussed many times before on this blog, in quantum mechanics a system is usually in a state of superposition of all possible states, until a measurement has been made or an outcome observed. In this interpretation of quantum mechanics, known as the Copenhagen interpretation, a top can spin clockwise and counterclockwise at the same time.
Indeed, the system is described by a wave function which tells us how likely the system is to be found in any one state. We can force the system into a single defined state only by an act of observation, which collapses the wave function. Thus, conceptually speaking, Jacob could be considered to be in a state of superposition of being dead and alive simultaneously. Why we do not observe macroscopic (visible to a naked eye) objects, such as people or animals, in a state of superposition is a difficult question not fully understood to this day. John von Neumann argued that, because the Schrödinger equation is linear, any linear combination of its solutions is also a solution (which is the very reason why quantum-mechanical objects could be in a state of superposition). No matter how large, any object is made of molecules, which in turn are made of atoms that are, in turn, made of subatomic particles. If subatomic particles obey the Schrödinger equation, so too must atoms, and so too must molecules, and thus so too must the object itself. Today, in fact, large groups of atoms and molecules are routinely put in a state of superposition in physics labs. There is no reason why a large object, say, a cat or a person, could not be in a state of superposition.
This paradoxical situation was illustrated by the Gedankenexperiment proposed by Erwin Schrödinger in 1933—the famous Schrödinger cat experiment. As described in the earlier chapter, “Two Beginnings,” the experiment begins as follows: a cat together with some radioactive material and a vial of poisonous prussic acid are placed in a closed chamber. A Geiger counter, which immediately detects when a single atom of radioactive material has decayed, is also placed inside the chamber. The Geiger counter is connected to a relay, which is connected to a hammer suspended over the vial of prussic acid. As soon as one radioactive atom decays, the Geiger counter detects the decay and trips the relay, which then releases the hammer that smashes the vial of poison, killing the cat. Based on the amount of radioactive material and its half-life, we can calculate that there is a 50% chance that, within, say, one hour, one atom of the radioactive material will decay. Prior to the observation, the state of the atom is a linear superposition of two possibilities: the decayed and not-decayed atom. Accordingly, the state of the cat, which is entangled with the rest of the system, is also a linear superposition of two physical possibilities: the cat is alive and the cat is dead. In other words, before the measurement takes place, the cat is in a surreal state of superposition of being dead and alive at the same time.
As we illustrated in many examples before, the Torah and Talmudic sages were very comfortable with the quantum way of thinking (that is, quantum logic) and used quantum-mechanical constructs freely. Thus, the sages have no difficulty viewing Jacob in a state of superposition of being dead and alive simultaneously.
This structural parallel goes even further. Just as in the Schrödinger cat experiment, where the feline is entangled with the radioactive material, the state of which determines the cat’s state (and fate), so too is Jacob’s fate entangled with that of his children. Indeed, Rav Yitzchak states, “The verse equates Jacob with his progeny: just as his progeny are alive, he too is alive.” In our quantum-mechanical parlance, we would say that Jacob is entangled with his progeny. Thus, the state of his progeny determines Jacob’s state—“just as his progeny are alive, he too is alive.”
The last interpretation proposed by the Shelah suggests that Israel died, whereas Jacob did not die. In other words, the Shelah suggest that both events took place—Jacob, as known by his name Israel, did die, whereas he, as known by his name Jacob, did not die. This approach is reminiscent of Hugh Everett’s many-worlds interpretation of quantum mechanics, in which every possibility is realized in different branches of the universe. Every event, according to Everett, causes our universe to branch out. In the Schrödinger cat experiment, the decay of the radioactive atom causes the universe to branch out into two daughter universes—in one, the atom decays and the cat dies; in the other, the atom does not decay and the cat does not die. It seems that the Shelah’s approach could be cast in similar terms. Jacob’s death caused our universe to branch into two universes—in one universe, where Jacob is known by his other name Israel, he dies; in the other, Jacob lives. Shelah, of course, knew nothing about the branching of the universe, but he may have used the two names of Jacob as a euphemism for what modern physics would call the branching of the universe into two.
Thus, three interpretations of the momentous event of the passing of our patriarch Jacob, when viewed allegorically, give us three models of the universe as described by three theories of physics.
 Strictly speaking, Torah does not say that Jacob died. When the Torah described the death of Abraham, it said, “And Abraham expiredand died (vayamat) in a good old age.” (Genesis 25:8) Similarly, it says about Isaac, “And Isaac expired, and died (vayamat), and was gathered unto his people…” (Genesis 35:29) Here, however, the Torah merely says that Jacob expired without mentioned that he died (vayamat). This glaring omission was the source of Rashi’s commentary: “But no mention is made of death in his regard. Our rabbis of blessed memory said, ‘Our father Jacob did not die.’” (Rashi on Genesis 49:33) In that Gemara Rabbi Yitzchak quotes Rabbi Yochanan who said that Jacob didn’t die. Rabbi Nachman argues that, albeit the Torah doesn’t say that he died, but it does say in the subsequent verse that Jacob was embalmed and that his children mourned for him and buried him. It is implicit that Jacob died.
 The same cave where Adam and Eve, Abraham and Sarah, Isaac and Rebecca, and his wife, Leah were buried.
 Yochanah (Johanan) bar Nappaha (or Nafcha) (180–279 CE) was a prominent sage (Amora) of Talmud. He is quoted thousands of times in Jerusalem and Babylonian Talmuds and is credited with compiling Jerusalem Talmud.
 See Maharsha on Taanit 5b and Rashba on Ein Yaakov, ibid.
 In his commentary on Taanit 5b, Rashi writes, “Our father Jacob did not die, but lives forever… the fact that the ‘embalmers embalmed’ was only because they thought he had died.”
 The Zohar, states that when a tzadik (a righteous person) departs, he is to be found in all the worlds more than during his lifetime.” (Zohar III, 71b) See also Tanya, Igeret HaKodesh, Epistle 27.
 Isaiah or Yeshayahu ben Avraham Horowitz (1555–1630), also known as the Shelah HaKadosh (“the holy Shelah”), was a great Rabbi and a Kabbalist in Prague. He is known by the acronym of his most famous work—the commentary on the Pentateuch, Shei Luchot HaBrit.
 Rabbi Isaiah Horowitz, Shnei Luchot HaBrit, Parshat Vayechi.
 The Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson, suggested in one of his talks that the reason Jacob is the only forefather of whom the Torah does not say that he died is this: Jacob personified the sefirah of Tiferet—the attribute of truth. Just as truth is immutable and eternal, so too Jacob has achieved immortality. However, this needs to be understood. The concept of truth must be considered in the context of the system of logic that is used. In logic, the semantic principle of bivalence states that every declarative sentence expressing a proposition has only one truth value—either true or false. A logic satisfying this principle is called a two-valued logic or bivalent logic. Aristotelian logic is an early example bivalent logic. However, it multi-valued logic, this is not necessarily the case. Thus, is the three-valued logic, there could three values of truth—true, false, and a third value that could be in between true and false or an unknown. It is possible to view quantum logic as a three-value logic, wherein the third value is the superposition of true and false. The first explanatory approach discussed above is an example of a two-valued logic where semantic principle of bivalence holds true. However, the second and the third approach should be analyzed in the context of three-valued logic, semantic principle of bivalence does not hold true. Alternatively, these ideas could be analyzed in the context of the law of excluded middle, which states that for any proposition, either that proposition is true or its negation is true.
 Rav Nachman bar Yaakov (died 320 CE)—a Talmudic sage, a third generation of Amoraim, who lived in Babylonia and was a chief justice of the exilarch’s court.
 Rabbi Yitzchak (Isaac) Nappacha, was a Talmudic sage who lived in 3rd-4th centuries, a second generation Amora from Galilee. He was a student of Rabbi Yochanan and is credited with calculating Rabbinite calendar, which is in use till today.
 See the footnote 5 above.
 For example, an electron can be in a superposition of states spin-up and spin-down, which is somewhat analogous to a top spinning clockwise and counterclockwise at the same time.
 This is called the Born rule: the square amplitude of the wave function gives the probability of finding the system in a particular area of the configurational space.
 Readers somewhat familiar with quantum mechanics may argue the process of decoherence (dissipation of information into a surrounding environment) destroys the state of superposition. However, it has been well-established that decoherence alone cannot fully account for the collapse of the wave function (and the state of superposition).
 A thought experiment. Unlike biologists, physicists do not sacrifice cats and other animals on the altar of science.