The Kabbalah concept of Tzimtzum

The tzimtzum or tsimtsum (Hebrew צמצום ṣimṣūm "contraction/constriction/condensation") is a term used in Kabbalah to explain the doctrine that God began the process of creation by "contracting" his Ohr Ein Sof (infinite light) in order to allow for a "conceptual space" in which finite and seemingly independent realms could exist.

This primordial initial contraction, forming a ḥālāl happānuy "vacant space" (חלל הפנוי) into which new creative light could beam, is denoted by general reference to the tzimtzum. In contrast to earlier, Medieval Kabbalah, this made the first creative act a concealment/Divine exile rather than unfolding revelation.

Because the tzimtzum results in the "empty space" in which spiritual and physical Worlds and ultimately, free will can exist, God is often referred to as "Ha-Makom" (המקום lit. "the Place", "the Omnipresent") in Rabbinic literature ("He is the Place of the World, but the World is not His Place"[1]).

In Kabbalistic interpretation, this describes the paradox of simultaneous Divine presence and absence within the vacuum and resultant Creation. Relatedly, Olam — the Hebrew for "World/Realm" — is derived from the root עלם meaning "concealment". This etymology is complementary with the concept of Tzimtzum in that the subsequent spiritual realms and the ultimate physical universe conceal to different degrees the infinite spiritual lifeforce of creation.

Their progressive diminutions of the Divine Ohr (Light) from realm to realm in creation are also referred to in the plural as secondary tzimtzumim (innumerable "condensations / veilings/ constrictions" of the lifeforce). However, these subsequent concealments are found in earlier, Medieval Kabbalah. The new doctrine of Luria advanced the notion of the primordial withdrawal (a dilug – radical "leap") in order to reconcile a causal creative chain from the Infinite with finite Existence.

"Prior to Creation, there was only the infinite Or Ein Sof filling all existence. When it arose in G-d's Will to create worlds and emanate the emanated ... He contracted (in Hebrew "tzimtzum") Himself in the point at the center, in the very center of His light. He restricted that light, distancing it to the sides surrounding the central point, so that there remained a void, a hollow empty space, away from the central point ... After this tzimtzum ... He drew down from the Or Ein Sof a single straight line [of light] from His light surrounding [the void] from above to below [into the void], and it chained down descending into that void. ... In the space of that void He emanated, created, formed and made all the worlds."
— Etz Chaim, Arizal, Heichal A"K, anaf 2[2]