Terms that are followed by an asterisk have their own entries in the glossary. All transliterations are from Hebrew.

Adam HaRishon (lit. “the first man”)—Biblical Adam

Adam Kadmon (lit. “primordial man”)—the will of the

Or Ein Sof* to create

Ahavat Hashem—love of G-d

Ahavat Yisrael—love of a fellow Jew

Aleph Bet—The Hebrew alphabet

Amidah—The silent prayer said while standing

Assiyah—The world of “action,” lowest of the four worlds of Creation

Atzilut—The world of “emanation,” highest of the four worlds of Creation

Atzmut—The essence of G-d

Avodat Hashem—service of G-d

Baal Teshuvah (lit. “a returnee”)—one who has become

observant of the commandments

Benoni—the intermediate person; between the Tzaddik* and the Rasha*

Beriah—The world of “creation,” second-highest of the four worlds of Creation

Binah—Sefirah* of understanding

Bitachon—trust in G-d

Bnai Yisrael (lit. “the children of Israel”)—the Jewish people

ChaBaD—acronym for Chochmah*, Binah*, Daat*—also the name of the worldwide chassidic* movement

ChaGaT—acronym for Chessed*, Gevurah*, and Tiferet*

Challah—bread used on Shabbat* and holidays

Chassid (pl. chassidim)—follower(s) of the chassidic* movement

Chassidic—movement of Judaism that focuses on the study of Kabbalah*; founded by the Baal Shem Tov

Hassidism—chassidic* philosophy

Chaya—Hebrew for “living one”; second-highest of five general souls

Chayot Hakodesh (lit. “holy beings”)—A Group of angels

Chessed—Sefirah* of kindness

Chochmah—Sefirah* of wisdom

Daat—Sefirah* of Knowledge

Daat Elyon—Supernal knowledge

Daat Tachton—terrestrial knoweldge

Dirah BeTachtonim—quoted from the Midrash*: G-d desired to have a “dwelling place in the lower worlds”; the purpose of Creation

Drush—“homiletical” interpretation of the Torah*; second highest level of Pardes*

Ein Sof (lit. “without end”)—the Infinite G-d as enclothed in Creation

Elokut—G-dliness

Emet—truth

Emunah—faith

Farbrengen—chassidic gathering

Gehinom—Hell

Gevurah—Sefirah* of strength

Gilgul—reincarnation

Hashgochah Pratit—Divine providence

hatzlachah—success

Havaye—the Tetragrammeton; four-letter name of G-d

Hiddur Mitzvah—Beautification of the Mitzvah*; i.e. doing a commandment in a beautiful way

Hod—Sefirah* of splendor

Kabbalah (lit. “received”)—mystical tradition of the Torah*

Kaddish—prayer recited in the memory of a departed soul

Kav—circular “beam” of pre-Tzimtzim* Light*

Kedushah—holiness

Kelipah (pl. Klipot; lit. “peel” for “shell”)—words used by

Kabbalah to describe coverings of impurity.

Kelipat Nogah (lit. “illuminating shell”)—Klipah* that can be utilized for good

Keter—Sefirah* of crown

Malchut—Sefirah* of kingship

Mashiach (lit. “anointed one”)—the Messiah

Mazal (pl. Mazalot)—constellation or planetary influence

Memale Kol Almin—Light* that fills all worlds; also referred to as the Kav*

Mezuzah—parchment scroll attached to doorpost

Midrash—anthology of rabbinic scriptural commentary

Mikvah—ritual bath used for spiritual purification

Mishnah—Oral Law of the Torah* compiled by Tannaim* under the leadership ofRabbi Yehudah Hanassi.

Mitzvah (pl. Mitzvot)—Divine commandment(s) derived from the Torah*

Modeh Ani—first words of the following prayer said immediately upon awakening: “I offer thanks to You, living and eternal King, for you have restored my soul within me; Your faithfulness is abundant.”

Mussar (lit. “rebuke”)—a movement of Judaism that encourages people to study ethics and morals and to improve character.

Nefesh—Hebrew for “soul of vitality”; lowest of five general souls

Nefesh Elokit—G-dly Soul of a person

Nefesh HaBehamit—Animalistic Soul of a person

NeHiY—acronym for Netzach*, Hod*, and Yesod*

Neshamah—Hebrew for “breath of life”; third-highest of five general souls

Netzach—Sefirah* of victory

Nigleh—revealed dimension of Torah*

Nistar—inner dimension of Torah*

Nistarim—clandestine Kabbalistics during the days of Baal Shem Tov

Olam (lit. “concealment”)—world

Olam Haba—the World to Come

Ophanim—Group of angels

Or - Light—English for “Or.” metaphor for Divine energy

Or Ein Sof—Hebrew for “Light of the Infinite”; metaphor for Divine energy used in Creation

Or Makkif—a peripheral Light*

Or Pnimi—an inner Light*

Pardes (lit. “orchard”)—acronym for four levels of Torah* study

Pshat—“simple” interpretation of the Torah*; most basic level of Pardes*

Rasha—wicked person

Rebbe—leader of Chassidim*

Remez—“illusionary.” interpretation of the Torah*; third highest level of Pardes*

Rosh Hashanah—The Jewish New Year

Ruach—Hebrew for “spirit”; fourth-highest of five general souls

Ruach Hakodesh (lit. “holy spirit”)—Divine inspiration

Seder Hishtalshlut—chain-ordered process used in Creation

Sefirah (pl. Sefirot)—a channel of Divine energy or attribute used in Creation

Seraphim—Group of angels

Shabbat—Sabbath

Simchah—joy

Shechinah—Divine Presence

Rabbi Menachem Mendel Schneerson
Lubavitcher Rebbe
Menachem Mendel Schneerson at the Lag BaOmer parade in Brooklyn, 1987.
Synagogue	770 Eastern Parkway, Brooklyn, NY
Began	10 Shevat 5711 / January 17, 1951
Predecessor	Yosef Yitzchok Schneersohn
Personal details
Born	April 5, 1902 OS (11 Nissan5662)[1] Nikolaev, Kherson Governorate,Russian Empire (present-dayMykolaiv, Ukraine)
Died	June 12, 1994 NS (3 Tammuz5754) (aged 92[2]) Manhattan, New York, USA
Buried	Queens, New York, USA
Dynasty	Chabad Lubavitch
Parents	Levi Yitzchak Schneerson ChanaYanovski Schneerson
Spouse	Chaya Mushka Schneerson
Semicha	Rogatchover Gaon

Rabbi Menachem Mendel Schneerson (April 5, 1902 – June 12, 1994), known as the Rebbe^[3][4] was an Orthodox rabbi, Talmudic scholar, and the last Lubavitcher Rebbe. He is considered one of the most influential Jewish leaders of the 20th century.^[5][6][7]

As leader of the Chabad-Lubavitch movement, he oversaw its expansion from a small group into the largest and most dynamic force in Judaism today,^[8] with an international network of over 3000 educational and social centers.^[9][10] The institutions he established include kindergartens, schools, drug-rehabilitation centers, care-homes for the disabled and synagogues.^[11]

Schneerson is noted for his contributions to Jewish continuity and religious thought,^[12] as well as his wide-ranging contributions to traditional Torah scholarship.^[13] He is recognized as the pioneer of Jewish outreach.^[14][15]

In 1978, the U.S. Congress designated Schneerson's birthday as the national Education Day U.S.A.,^[16] honoring his role in establishing the Department of Education as an independentcabinet-level department.^[17] In 1994, he was posthumously awarded the Congressional Gold Medal for his "outstanding and lasting contributions toward improvements in world education, morality, and acts of charity." ^[18]

Life[edit]

1902-1923[edit]

Menachem Mendel Schneerson was born on Friday, April 18, 1902, equivalent to 11 Nissan, 5662, in the town of Nikolaev.^[19] His father was Rabbi Levi Yitzchak Schneerson, a renowned Talmudic scholar and authority on Kabbalah and Jewish law.^[20] His mother was Rebbetzin Chana Schneerson (nee Yanovski). He was named after the third Chabad rebbe, the Tzemach Tzedek, from whom he was descendent in direct paternal lineage.

In 1907, when Menachem Mendel was six years old, the Schneersons moved to Yekatrinislav (today, Dnepropetrovsk), where Rabbi Levi Yitzchak was appointed Chief Rabbi of the city. He served until 1939, when he was exiled by the Soviets to Uzbekistan.^[21] Schneerson had two younger brothers, Dov Ber who was murdered in 1944 by Nazi collaborators and Yisrael Aryeh Leib, who died in 1952 while completing doctoral studies at Liverpool University.^[22]

Schneerson who was described as a slim boy with blond hair,^[23] was gifted with extraordinary intelligence and empathy.^[24] During his youth, he received a private education and was tutored by Zalman Vilenkin from 1909 through 1913. When Schneerson was eleven years old, Vilenkin informed the boy's father that he had nothing more to teach his son.^[25] At that point, Rabbi Levi Yitzchak began teaching his son Talmud and rabbinic literature, as well as Kabbalah. Schneerson proved gifted in both Talmudic and Kabalistic study and also took exams as an external student of the local Soviet school.^[26] He was considered an Illui and genius, and by the time he was seventeen, he had mastered the entire Talmud, some 5,894 pages with all its early commentaries.^[27]

Ebla
Ruins of the outer wall and the "Damascus Gate"
Shown within Syria
Alternate name	Tell Mardikh (Arabic: تل مرديخ‎)
Location	Idlib Governorate, Syria
Coordinates	35.798°N 36.798°E
Type	settlement
History
Founded	c. 3500 BC
Abandoned	7th century AD
Periods	Bronze Age
Site notes
Excavation dates	1964–present
Archaeologists	Paolo Matthiae
Ownership	Public
Public access	Yes

A clay tablet found in Ebla, Syria

The Ebla tablets are a collection of as many as 1800 complete clay tablets, 4700 fragments and many thousand minor chips found in the palace archives^[1] of the ancient city of Ebla, Syria. The tablets were discovered by Italianarchaeologist Paolo Matthiae and his team in 1974–75^[2] during their excavations at the ancient city of Tell Mardikh.^[3] The tablets, which were found in situ on collapsed shelves, retained many of their contemporary clay tags to help reference them. They all date to the period between ca. 2500 BC and the destruction of the city ca. 2250 BC.^[4] Today, the tablets are being held in the Syrian museums of Aleppo, Damascus, and Idlib.

Language[edit]

Two languages appeared in the writing on the tablets: Sumerian, and a previously unknown language that used the Sumerian cuneiform script (Sumerian logograms or "Sumerograms") as a phonetic representation of the locally spoken Ebla language.^{[citation needed]} The latter script was initially identified asproto-Canaanite by professor Giovanni Pettinato, who first deciphered the tablets, because it predated the Semitic languages of Canaan, like Ugaritic andHebrew. Pettinato later retracted the designation and decided to call it simply "Eblaite", the name by which it is known today.^[4]

The purely phonetic use of Sumerian logograms marks a momentous advance in the history of writing.^[5] From the clumsier system developed by Sumerian scribes, employing a mixed use of logograms and phonetic signs, the scribes at Ebla employed a reduced number of signs from the existing systems entirely phonetically, both the earliest example of transcription (rendering sounds in a system invented for another language) and a major simplifying step towards "reader friendliness" that would enable a wider spread of literacy in palace, temple and merchant contexts.

Archaeological context[edit]

The tablets were discovered just where they had fallen when their wooden shelves burned in the final conflagration of "Palace G". The archive was kept in orderly fashion in two small rooms off a large audience hall (with a raised dais at one end); one repository contained only bureaucratic economic records on characteristic round tablets, the other, larger room held ritual and literary texts, including pedagogical texts for teaching young scribes. Many of the tablets had not previously been baked, but when all were preserved by the fire that destroyed the palace, their storage method served to fire them almost as thoroughly as if in a kiln: they had been stored upright in partly recessed wooden shelves, rectos facing outward, leaning backwards at an angle so that the incipit of each tablet could be seen at a glance, and separated from one another by fragments of baked clay. The burning shelving pancaked – collapsing in place and preserving the order of the tablets.^[6]

In physical cosmology, the Copernican principle, named after Nicolaus Copernicus, states that the Earth is not in a central, specially favored position in theuniverse.^[1] More recently, the principle has been generalized to the relativistic concept that humans are not privileged observers of the universe.^[2] In this sense, it is equivalent to the mediocrity principle, with important implications for the philosophy of science.

Since the 1990s the term has been used (interchangeably with "the Copernicus method") for J. Richard Gott's Bayesian-inference-based prediction of duration of ongoing events, a generalized version of the Doomsday argument.

Origin and implications[edit]

Michael Rowan-Robinson emphasizes the Copernican principle as the threshold test for modern thought, asserting that: "It is evident that in the post-Copernican era of human history, no well-informed and rational person can imagine that the Earth occupies a unique position in the universe."^[3]

Hermann Bondi named the principle after Copernicus in the mid-20th century, although the principle itself dates back to the 16th-17th century paradigm shift away from the Ptolemaic system, which placed Earth at the center of the universe. Copernicus proposed that the motion of the planets can be explained by reference to an assumption that the Sun and not the Earth is centrally located and stationary. He argued that the apparent retrograde motion of the planets is an illusion caused by Earth's movement around the Sun, which the Copernican model placed at the centre of the universe. Copernicus himself was mainly motivated by technical dissatisfaction with the earlier system and not by support for any mediocrity principle.^[4] In fact, although the Copernican heliocentric model is often described as "demoting" Earth from its central role it had in the Ptolemaic geocentric model, neither Copernicus nor other 15th- and 16th-century scientists and philosophers viewed it as such.^[5][6] It wasn't until the late 20th Century that Carl Sagan could claim "Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people.".^[7]

In cosmology, if one assumes the Copernican principle and observes that the universe appears isotropic or the same in all directions from our vantage-point on Earth, then one can infer that the universe is generally homogeneous or the same everywhere (at any given time) and is also isotropic about any given point. These two conditions make up the cosmological principle.^[3] In practice, astronomers observe that the universe has heterogeneous or non-uniform structures up to the scale of galactic superclusters, filaments and great voids. It becomes more and more homogeneous and isotropic when observed on larger and larger scales, with little detectable structure on scales of more than about 200 million parsecs. However, on scales comparable to the radius of the observable universe, we see systematic changes with distance from the Earth. For instance, galaxies contain more young stars and are less clustered, and quasars appear more numerous. While this might suggest that the Earth is at the center of the universe, the Copernican principle requires us to interpret it as evidence for the evolution of the universe with time: this distant light has taken most of the age of the universe to reach and shows us the universe when it was young. The most distant light of all,cosmic microwave background radiation, is isotropic to at least one part in a thousand.

Modern mathematical cosmology is based on the assumption that the Cosmological principle is almost, but not exactly, true on the largest scales. The Copernican principle represents the irreducible philosophical assumption needed to justify this, when combined with the observations.

Bondi and Thomas Gold used the Copernican principle to argue for the perfect cosmological principle which maintains that the universe is also homogeneous in time, and is the basis for the steady-state cosmology.^[8] However, this strongly conflicts with the evidence for cosmological evolution mentioned earlier: the universe has progressed from extremely different conditions at the Big Bang, and will continue to progress toward extremely different conditions, particularly under the rising influence of dark energy, apparently toward the Big Freeze or Big Rip.

GALILEO AND EINSTEIN Overview and Lecture Index

1. Counting in Babylon      PDF      Spanish Version     Belorussian Version

Babylon had in all probability the earliest written language. At the same time, an elegant system of weights and measures kept the peace in the marketplace. Their method of counting was in some ways better than our present one! We look at some ancient math tables, and ideas about Pythagoras' theorem 1,000 years before Pythagoras.

2. Early Greek Science: Thales to Plato    PDF    Spanish Version

In the ancient port city of Miletus, there took place a "discovery of nature": philosophers tried to understand natural phenomena without invoking the supernatural. The Greeks imported basic geometric ideas from Egypt, and developed them further. Members of the Pythagorean cult announced the famous theorem, and the (to them) alarming discovery of irrational numbers! The Greeks had some ideas about elements and atoms. Hippocrates looked for non-supernatural causes of disease. Plato formulated a rationale for higher education, and thought about atoms.

3. Motion in the Heavens: Stars, Sun, Moon, Planets

A brief review for moderns of facts familiar to almost everybody in the ancient world: how the sun, moon and planets move through the sky over the course of time.

4. Aristotle

A brief look at the beginnings of science and philosophy in Athens: Plato's Academy and Aristotle's Lyceum. On to Aristotle's science: "causes" in living things and inanimate matter, Aristotle's elements, and laws of motion.

5. Measuring the Solar System

We look at some startlingly good measurements by the Greeks of the size of the earth and the distance to the moon, and a less successful (but correct in principle) attempt to find the distance to the sun.

6. Greek Science after Aristotle

Strato understood that falling bodies pick up speed (contrary to Aristotle's assertions). Aristarchus gave a completely correct view of the solar system, anticipating Copernicus by 2,000 years or so. Science flourished for centuries in Alexandria, Egypt: Euclid, Apollonius, Hypatia and others lived there, Archimedes studied there. Archimedes understood leverage and buoyancy, developed military applications, approximated Pi very closely, and almost invented calculus! (See also the next lecture.)

7. Basic Ideas in Greek Mathematics

Nailing down the square root of 2. Zeno's paradoxes: Achilles and the tortoise. Proving an arrow can never move - analyzing motion, the beginning of calculus. How Archimedes calculated Pi to impressive accuracy, squared the circle, and did an integral to find the area of a sphere.

8. How the Greeks used Geometry to Understand the Stars

The universe is like an onion of crystal spheres: Plato, Eudoxus, Aristotle. More earthly ideas: Eudoxus and Aristarchus. Understanding planetary motion in terms of cycles and epicycles: Hipparchus and Ptolemy. These methods were refined to the point where they gave accurate predictions of planetary positions for centuries (even though Ptolemy believed the earth was at rest at the center of the universe).

How Greek Science Reached Baghdad    PDF

Some Later Islamic Science   PDF

9. Galileo and the Telescope

Copernicus challenged Ptolemy's worldview. Evolution of the telescope. Galileo saw mountains on the moon, and estimated their height - the first indication that the moon was earthlike, not a perfect ethereal sphere at all.

10. Life of Galileo

A few facts and anecdotes to try to give something of the flavor of Galileo's life and times, plus references to books for those who would like a more complete picture.

11. Scaling: why giants don't exist

One of Galileo's most important contributions to science (and engineering): the realization that since areas and volumes scale differently when the size of an object is increased keeping all proportions the same, physical properties of large objects may be dramatically different from similar small objects, not just scaled up versions of the same thing. We explore some of the consequences.

12. Galileo's Acceleration Experiment

Galileo argued against Aristotle's assertions that falling bodies fall at steady speeds, with heavier objects falling proportionately faster. Galileo argued that falling bodies pick up speed at a steady rate (until they move so fast that air resistance becomes important). He constructed an experiment to prove his point (and we reproduced it).

13. Naturally Accelerated Motion

This lecture presents the core of Galileo's analysis of motion in free fall, which he referred to as "naturally accelerated motion". This is challenging material if you're new to it, but crucial in progressing from an Aristotelian or medieval worldview to that of Galileo and Newton, the basis of our modern understanding of nature. Galileo used his new-found understanding of falling motion to prove that a projectile follows a parabolic path, if air resistance can be ignored.