Principle of Least Action I
The least action principle is an expression of teleological reasoning where the initial states of the system are determined by the endpoints—the beginning and the end.
What Is a Soul? II. Anatomy of the Soul
In the biblical story of the creation of Adam, the Torah states: Then the Eternal G‑d formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul.Genesis 2:7 The word translated into English as “soul” in the original Hebrew is nefesh. This is the first and the lowest level of the soul given to Adam. The taxonomy and anatomy of a soul in Judaism are quite complex. Original biblical sources speak of three levels of the soul: nefesh (“soul”), ru’ach (“spirit”),[1] and neshamah (“breath”).[2] The Kabbalah speaks of the five levels of the soul: nefesh, ru’ach, neshamah, chayah, and yechidah. This is based on classical rabbinic sources. As stated in the midrash, “By five names is the soul called: nefesh, ru’ach, [...]
Physics of Tzimtzum II — Collapse of the Wave Function
In the previous post “Physics of Tzimtzum I—The Quantum Leap”, we gave a general overview of the mystical doctrine of tzimtzum—the cornerstone of Lurianic Kabbalah. It is time to get into the details. The first phrase that describes the process of tzimtzum in Etz Chaim states: Ein Sof “contracted” (tzimtzem) Himself in the point at the center, in the very center of Ohr Ein Sof. This sentence raises several difficult questions: First, what could it possibly mean that the Infinite (Ein Sof) “contracted” (tzimtzem) Himself? In Hebrew, the word tzimtzum comes from the root TZM, which means “to diminish” or “to fast,” that is, to “diminish” oneself.[1] It can also mean “to be precise,” that is, to remove ambiguity.[2] The repetition of the root TZM is a grammatical form of doubling down, an extreme [...]
Physics of Tzimtzum I — The Quantum Leap
Introduction “In the beginning G‑d created the heavens and the earth.” (Genesis 1:1) “In the beginning G‑d created the heavens and the earth,” the Torah says. However, what was before the “beginning”? It is like asking, What was before the Big Bang? In physics, until relatively recently, such questions were discouraged. The prevailing wisdom was that time and space had been created by the Big Bang, and there was no “before” before the Big Bang. Mishnah discourages such thinking, too. The sages point out that the first letter of the Torah, the letter bet, is open on the left and closed on the right:[1] The text of the Torah and the history of the world proceed from that opening on the left. The closed right side of the letter bet visually walls off [...]
Quantum Cheshire Cat vs. Venomous Snakes
A Study in Form and Matter And Moses prayed for the people. And the Eternal said unto Moses: “Make thee a fiery serpent, and set it upon a pole; and it shall come to pass, that every one that is bitten, when he seeth it, shall live.” And Moses made a serpent of brass, and set it upon the pole; and it came to pass, that if a serpent had bitten any man, when he looked unto the serpent of brass, he lived. (Numbers 21:8-9) The Torah portion, Chukat, tells a bizarre story. Jews complain against G‑d and Moses. G‑d gets angry and sends venomous snakes that bite and kill many Jews. The people repent and ask Moses to pray for them. In response to Moses’s prayer, G‑d instructs him to make a [...]
Counting Weeks and Days
There is a Biblical Commandment to count the days between the Passover and Shavuot, the Feast of Weeks (a.k.a. Pentecost). We start counting on the second day of Passover (the first day of the barley harvest in the land of Israel, when the wave-offering of the omer, i.e., “sheaf,” of ripe barley was made in the Jerusalem Temple) and finish on the eve of Shavuot—the day when two loaves of bread made of wheat were offered at the Temple. There are exactly seven weeks (forty-nine days) between these two holidays; we are commanded to count the weeks and the days. These forty-nine days are called days of Sefirat HaOmer (the ays of “counting the Omer”) or simple days of Sefirah. This commandment is given in the following verses of the Torah: And ye shall count [...]
Wigner’s Friend Paradox
Amicus est Socrates, magister meus, sed magis est amica veritas. “Socrates is my friend but a greater friend is truth” – Plato c. 428-348 BCE. Amicus Plato, sed magis amica veritas. “Plato is my friend, but a greater friend is truth" – Aristotle, Nicomachean Ethics, 350 BCE. Amicus Plato amicus Aristoteles magis amica veritas. “Plato is my friend, Aristotle is my friend, but a greater friend is truth.” – Isaac Newton, Cambridge Student Notebook, 1661 You are my friend, but what is truth? – Eugene Wigner, 1961 If Isaac Newton summed up the aphorisms of Plato and Aristotle in his student notebook, exactly 300 years later, Eugene Wigner put this notion on its head. Although taking a poetic license, I put Wigner's words above in quotation marks, I do not know if he [...]
The Puzzle of Pi
March 14 is celebrated by nerds around the world as the Pi Day. When written in digits, 3/14 represents first three digits of the number traditionally represented by the Greek letter “π” (pronounced pi) – 3.14. Pi Day is celebrated by eating pie and discussing the significance of π. Some folks who have too much time on their hands compete at memorizing decimal digits representing the value of pi. The record presently stands at 67,890 digits! While eating pie is optional, discussing the significance of π is truly mandatory. So, what is π and why is to so important? π is arguably the most famous mathematical constant, expressing the ratio between the circumference of a circle and its diameter. If you take a circle with a diameter of 1, the circumference of this [...]
Joseph—the Master of Time
The story of Joseph’s incarceration ends with his successful interpretation of the dreams of the Pharaoh’s chief butler and the chief baker. He ingeniously interpreted ordinary objects (tendrils of grapes and baskets of bread) as symbols of the units of time (Interpreting Dreams). Even greater insight was Joseph’s understanding that the engagement in time, manifested by the chief butler’s personally squeezing the grapes into the cup and placing the cup in Pharaoh’s hand, symbolized life for the chief butler. Conversely, the passivity of the chief baker, who dreamt of baskets of bread sitting on his head, with birds eating from the baskets, symbolized the opposite of life. Girolamo Brusaferro [...]
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 [...]