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Quantum Theory

/Quantum Theory

Abraham Meets Abraham from a Parallel Universe

And he [Abraham] lifted up his eyes and looked, and, lo, three men stood over against him…  (Gen. 18:2)   On this blog, we often discuss a collapse of the wavefunction as the result of a measurement. This phenomenon is called by some physicists the “measurement problem.” There are several reasons, why the collapse of the wavefunction—part and parcel of the Copenhagen interpretation of quantum mechanics—is called a problem. Firstly, it does not follow from the Schrödinger equation and is added ad hoc. Secondly, nobody knows how it happens or how long it takes to collapse the wavefunction.  This is not to mention that any notion that the collapse of the wavefunction is caused by human consciousness leading to Cartesian dualism is anathema to physicists. It is a problem, no matter how you [...]

Quantum Cheshire Cat and Resurrection

In memory of my father, Abraham Shamshin ben Reuven, ע"ה   For those of us who can't get enough of Schrödinger cat, comes a new feline—Quantum Cheshire Cat—the creation of an Israeli physicist, Yakir Aharonov. In Alice in Wonderland, Alice meets a grinning Cheshire cat. To her amazement, the cat disappears leaving only his grin behind: "All right', said the Cat; and this time it vanished quite slowly, beginning with the end of the tail, and ending with the grin, which remained some time after the rest of it had gone. Well! I've often seen a cat without a grin, but a grin without a cat! It's the most curious thing I ever saw in my life!" According to Martin Gardner, the statement "a grin without a cat" is a reference to mathematics dissociating itself [...]

Symmetry and Love — Jewish Chromodynamics

Ye are standing this day all of you before the Lord your God: your heads, your tribes, your elders, and your officers, even all the men of Israel, your little ones, your wives, and thy stranger that is in the midst of thy camp, from the hewer of thy wood unto the drawer of thy water; that thou shouldest enter into the covenant of the Lord thy God—and into His oath—which the Lord thy God maketh with thee this day. (Deut. 29:9-11) The above verses at the beginning of the Torah portion Nitzavim that is always read in the week preceding the Jewish New Year, Rosh HaShanah, are usually interpreted in terms of the unity of Jewish people: You are standing this day all of you [read: standing together in perfect unity]. This is not [...]

First Fruits and the Wave-Particle Duality of Nature

…Thou shalt take of the first of all the fruit of the ground, which thou shalt bring in from thy land that the Lord thy God giveth thee; and thou shalt put it in a basket and shalt go unto the place which the Lord thy God shall choose to cause His name to dwell there. And thou shalt come unto the priest that shall be in those days, and say unto him: 'I profess this day unto the Lord thy God, that I am come unto the land which the Lord swore unto our fathers to give us.' And the priest shall take the basket out of thy hand, and set it down before the altar of the Lord thy God. (Deut. 26:2-4) And the priest shall take the basket out of [...]

The Pilot Wave

And on the day that the tabernacle was reared up the cloud covered the tabernacle, even the tent of the testimony; and at even there was upon the tabernacle as it were the appearance of fire, until morning. So it was always: the cloud covered it, and the appearance of fire by night. And whenever the cloud was taken up from over the Tent, then after that the children of Israel journeyed; and in the place where the cloud abode, there the children of Israel encamped. At the commandment of the Lord the children of Israel journeyed, and at the commandment of the Lord they encamped: as long as the cloud abode upon the tabernacle they remained encamped. And when the cloud tarried upon the tabernacle many days, then the children of Israel [...]

Mishkan – a Metaphor for Quantum Reality, II

Continuing the theme of my last post, Mishkan – a Metaphor for Quantum Reality, the analogy between the Tabernacle (“Mishkan”) and quantum reality goes even deeper. The quantum world is best described today by the Quantum Field Theory. According to this theory, there are no particles, only fields. When we interact with a field, it manifests itself as a quantum of the field, which, to some extent, looks and behaves like a particle. For example, when we interact with an electromagnetic field, it manifests itself as a photon – a quantum of the electromagnetic field. An electron, according to the Quantum Field Theory, is not really a particle but a quantum of the electron field, which is a quantum field that is spread across the entire universe. This quantum is an excitation of [...]

Mishkan – a Metaphor for Quantum Reality

And when the Tabernacle is set to travel, the Levites shall take it down; and when the Tabernacle camps, the Levites shall set it up… (Num. 1:51) During the wonders of Israelites in the desert, the Tabernacle (Heb. “Mishkan”), existed as a sanctuary only during their encampments. Whenever they traveled, the Mishkan was taken down and disassembled to be carried by Levites during the journey. When God commanded Moses to set the camp, the Mishkan was reassembled and set up again. Let us fast forward some three-and-a-half thousand years to the beginning of the 20 c. It was a time of great intellectual turmoil. The discovery of the atom’s structure by Rutherford, according to which atom resembled a solar system with a nucleus at the center and electrons orbiting the nucleus, was followed [...]

Half-Shekel – Metaphor for Entanglement

This they shall give, everyone who goes through the counting: half a shekel according to the holy shekel. Twenty gerahs equal one shekel; half of a shekel shall be an offering to the Lord Ex. 30:13 In this week’s Torah portion, Ki Tisa (Ex. 30), Jewish people are given the commandment of donating a coin as atonement, not just a coin – half a coin. But why half? If God thought, twenty gerahs would be too much, He could have commanded Moses to mint another coin worth ten gerahs. But no, the coin was to remain what it was—worth twenty gerahs—and Jews were to give half a coin. Don’t you find it peculiar? I don’t, because half-coins are my favorite metaphor when explaining entanglement to my physics students. What is entanglement? When obtaining [...]

Sacrifices and incenses – fields and entanglement

(Recent Purim celebrations distracted me from writing on the weekly Torah portion. But I didn’t want to miss the opportunity to share my thoughts on the last week’s Torah portion – Tetzaveh. So here it is.) At the end of the weekly portion, Tetzaveh, Torah speaks of the burnt offerings (Heb. qorbanot) and the incense offerings (Heb. qetoret). The Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson, contrasts these two types of offerings by highlighting their symbolism. The Hebrew word for a burnt offering or sacrifice, qorban, is etymologically related to the word  qarov “close,” qiruv “to bring close” and qerovim “relatives,” as they all share the same root QRB “to be close.” Sacrificial offering (qorban) meant to bring a person who brought it close (qarov) to God. The Hebrew word for incense offerings, qetoret, [...]

Purim: Celebrating Randomness

The story of Purim, which we read in the Book of Esther, is a story about a righteous Jewish leader who held fast to his principles refusing to bow down to a rabid anti-Semite. It’s a story about a courageous Jewish queen, Esther, who saved her people risking her life. And yet, this holiday is not called by the name of Mordechai or Esther, it  is called Purim, because, as the Book of Esther informs us: For Haman the son of Hammedatha the Agagite, the adversary of all the Jews, had devised to destroy the Jews, and he cast the pur—that is the lot—to terrify them and destroy them… Therefore, they called these days Purim after the name pur. (Book of Esther, 9:24,26) This is odd because the casting of the lot (pur) [...]