Passover, Shabbat and the Principle of Least Action

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Passover, Shabbat and the Principle of Least Action

There is hardly a Jewish holiday more widely celebrated than Passover (Pesach). Jews of all denominations, affiliations, and levels of religious observance—if any at all—gather at the Passover Seder to tell the story of the Exodus from Egypt. What is often lost amid all of the beautiful rituals, not least among them the singing of Had Gadia and other Seder songs, is the deep meaning of this holiday, which is far more profound than a mere recollection of historical events, no matter how important they may be. What is, then, the deeper meaning of Pesach that transcends its historical significance?

On the morrow of Shabbat

One obscure and little-known (outside of the observant Jewish community) mitzvah may lead us to a deeper understanding of the meaning of Pesach – this is the commandment to count the Omer, i.e., to count 49 days between Pesach and the next holiday, Shavuot. The Torah states,

“Count for yourselves from the morrow of Shabbat…” (Lev. 23:15)  

Our sages teach us that, in this verse, Shabbat is a euphemism for Pesach (Mishna 65a). And, in accordance with this statement, we start counting the Omer from the second night of Pesach. Why did the sages, however, equate Shabbat with Pesach? Was it, perhaps, to give us a glimpse of the meaning of Pesach through seeing it through the lens of Shabbat? Let us try to understand what the meaning of Shabbat is, and how it elucidates the meaning of Pesach.

Divine Rest

The Torah says,

“In six days G-d created Heaven and Earth; and on the seventh day, He rested.” (Gen. 20:11)

What does it really mean that God rested after creating Heaven and Earth? Did He get tired? Can the Omnipotent God get tired? The Medrash says that it was as easy for G-d to create the world as it is for us to pronounce the letter Heh, the fifth letter of Hebrew aleph bet, which is merely an act of exhaling. The Sages are telling us that creation was effortless for G-d. (Bereshit Rabba 3:2, 10:12.) If G-d cannot get tired, then what does divine rest mean?

We shall approach this question by asking an easier and more general one: what is the meaning of rest? Let’s look at physics. The cardinal principle of physics is the principle of least action, a.k.a. the principle of stationary action, which roughly states that any system evolves in time so that its action (a function closely related to energy) is stationary. In other words, the system always chooses a path so that its action remain at rest as if being at rest is the ultimate goal of the physical system. Simply put, every system gravitates towards the state of rest.

One of the first scientists to formulate the principle of least action was Pierre Louis Maupertuis, who felt that “Nature is thrifty in all its actions.”

In the 17th century, Pierre de Fermat postulated that “Light travels between two given points along the path of shortest time.” Known as the principle of least time or Fermat’s Principle, this was one of the first formulations of the principle of least action.

He applied the principle broadly:  “The laws of movement and of rest deduced from this principle being precisely the same as those observed in nature, we can admire the application of it to all phenomena. The movement of animals, the vegetative growth of plants … are only its consequences; and the spectacle of the universe becomes so much the grander, so much more beautiful, the worthier of its Author, when one knows that a small number of laws, most wisely established, suffice for all movements.” (Chris Davis. Idle theory)  Leonard Euler gave the least action principle a mathematical formulation later that year.  There is evidence that Gottfried Leibniz first formulated the least action principle in 1707. The modern formulation of the least action principle was given by the Euler–Lagrange equation in the 1750s.



Similarly, the second law of thermodynamics states that the entropy (the measure of disorder) of any closed system increases with time. Chaos increases because the system evolves towards the state of the lowest energy—the state of thermodynamic equilibrium.

This teleological behavior of a physical system aiming at achieving a certain goal—the state of rest—has profound philosophical ramifications. If rest is the teleological goal of evolution of every system in physics, perhaps we can generalize this notion and define a broader concept of rest as the state of achieving a certain goal—one rests having achieved one’s goal.

This notion finds its support in the Hebrew language. The Hebrew word for “rest,” מנוחה (menucha), shares the same two-letter root—נ (nun) ח (chet)—with the word הנחיה (hanchiyah), “guidance,” i.e., leading towards a goal. Thus, when Moses questions God’s intentions in leading Israelites to the Promised Land, Gd replies, “פָּנַי יֵלֵכוּ, וַהֲנִחֹתִי לָךְMy Presence will go with thee and I will give thee rest.” (Ex. 33:14) Alternatively, the last phrase can be translated as “…and I will guide thee [to the Holy Land].”

The other word that shares the same tow-letter root—נ (nun) ח (chet)—is the word נחת (nachat), which can be translated as satisfaction, gratification, contentment or rest. One experiences all these emotions—satisfaction, gratification, and contentment—having reached one’s goal, i.e., one is at rest having achieved the state of psychological equilibrium.

Now we can understand the meaning of the divine rest. God set out to create the world. He toiled six days creating Heaven and Earth and, having completed His creation, He rested on the seventh day, Shabbat, having achieved His goal of creation. Our required rest on Shabbat is a way to connect ourselves with the Divine purpose of creation and proclaim a purposefulness of being. When we celebrate Shabbat, we recognize our Creator and celebrate His Purpose in the creation.

Higher Shabbat and Lower Shabbat

The Zohar states that there are two Shabbats – the higher Shabbat and the lower Shabbat.

It is difficult to imagine that the whole purpose of Creation was merely the creation of the material world as beautiful, as it was. As our sages teach, God created this world for the sake of man, the only being in the universe, endowed with freedom of choice and the ability to serve the Creator out of free will. This is why we celebrate Jewish New Year—Rosh HaShanah—not on the 25th day of Elul, when the physical world was first created, but five days later, on the first day of Tishrei when Adam and Chavah (Eve) were created. It is no accident, therefore, only after God created man—the “crown of creation”—on the sixth day, God was able to rest on the seventh.

Originally, this mission of serving the Creator was given to all mankind, but Adam and Eve disobeyed the will of the Creator, thereby missing the opportunity to realize the purpose of creation. …Then Cain killed Havel and the humanity went downhill from there. Regrettably, the humanity as a whole failed its mission.

By taking the people of Israel out of Egypt, God chose His people and sanctified them, and gave them the mission to fulfill His will—to bring Godly light into the world. The Exodus from Egypt marks the birth of the Jewish people as a nation. It also marks the covenant between God and His people. Thus, at the moment of the Exodus, the original plan of creation was finally realized. In this light, the Exodus takes on a cosmic significance, comparable to the creation of the world. That is precisely why the Torah calls Pesach—Shabbat. Just as the first Shabbat celebrated the completion of creation of the physical world, the Exodus from Egypt signified the realization of the spiritual purpose of Creation.

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About the Author:

Alexander Poltorak was trained as a theoretical physicist in Russia. He is Chairman and CEO of General Patent Corporation. Dr. Poltorak served as an Assistant Professor of Biomathematics at Cornell University Medical College, as an Assistant Professor of Physics at Touro College, he guest-lectured at Columbia University School of Engineering and Business School. He is presently affiliated with the CUNY serving as an adjunct professor of physics at the City College of New York and Research Fellow at the Institute for Ultrafast Spectroscopy and Lasers. Alex Poltorak authored several books and many articles. He blogs about physics, kabbalah and Jewish philosophy.


  1. dovid kaplan April 3, 2013 at 7:55 am - Reply

    i found this article so informative, stimulating and inspirational. it is not only written well, the concepts flowing seamlessly to each other, but in a way that glorifies Torah & Mitzvahs… Chazak U’Boruch!

  2. Tomer Tamarkin April 16, 2017 at 11:43 am - Reply

    Outstanding article. The differentiation between the 25th day of Elul and the first day of Tishrei or the day of “The Creation” is not well understood by most Jews. This has been explored by Dr. Gerald Schroeder in an attempt to reconcile the “biblical age” of the world (and Universe) with the age of the world (and Universe) based on physics. I would be interested in this author’s views on Schroeder’s paper at:

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