I want to preface this essay by declaring that I cannot know for sure whether what I am about to write is correct. This essay merely represents the closest I can get to a possible answer. I leave it to those far greater than myself to determine whether in fact God has allowed me to arrive at the correct answer.
Currently, the physics world is abuzz with the multiverse hypothesis, the claim that there could be multiple physical universes existing throughout the vast expanse of space. I don’t personally agree with the reason physics posits for the claim that they need such an idea. It seems to me largely designed to suit their claims that the miracle of life on earth is a random event, which could occur without Divine intervention. However, the idea did get me wondering whether there could be multiple tzimtzum bubbles throughout the Infinite Light.
According to Lurianic Kabbalah, God withdrew His Infinite Light, evenly all around to form a spherically shaped space within which to create various realms, both spiritual and physical. Kabbalah refers to this process as the “tzimtzum”. I asked two instructors of Kabbalah, whether this process could of happened more than once - making for multiple tzimtzum bubbles within the Infinite Light. To my surprise I was told that they didn’t think so, but, if such a thing would happen, the resultant tzimtzum bubbles wouldn’t really be different from each other.
I still don't understand why they answered me as they had. I figured that Infinite potential could easily bring forth a vast variety of forms. However, I have a hypothesis that perhaps this unexpected limit is introduced by starting with a fixed foundation, namely that of male/female duality. The tzimtzum is really the emergence of the ultimate cosmic female. Once the cosmic female emerges, the Infinite Light becomes, seemingly by default, the ultimate cosmic male - in relation to her. With such a fixed foundation, the variety of outcomes are more limited than expected.
Ultimately, there can only be one cosmic female on this level. The way the tzimtzum is emerges is by polarizing and gathering all feminine potential from within the Infinite Light. Just as there can only be one Infinite Light, there can only be one entity which has gathered up all feminine potential to become the Infinite Light’s polar opposite.
There also is a principle, which I have seen mostly used in Rabbi Ashlag’s school (but I also saw Rabbi Aryeh Kaplan employ it as well), that on the spiritual level spatial closeness and distance is defined by similarity and dissimilarity. Two entities which are similar are said to be close. Two entities which are dissimilar are said to be distant. It’s a lot like psychological closeness and distance. Two people who are neighbors can be distant and two people on different ends of the planet can be close. So what happens spiritually if two entities progressively become the same? Based on this thinking, we have to say that they eventually merge into one entity, one identity. There’s no longer a “two”. Similarly, two entities which are exactly the same to begin with can never even begin to emerge as distinct. In spirituality, exact duplication does not exist. Only a “difference” can produce a number “two”.
So under such circumstances, identical tzimtzum bubbles can never yield two separate bubbles. With each bubble being the same, by the spiritual rules of space, they’d just be too similar to become two.
Can there be a reality of a tzimtzum minus something to create the necessary difference for there to be a second tzimtzum in the Infinite Light? Such a measure would create a “difference”. However, it would not exist in the Infinite Light on the same level as the Lurianic tzimtzum bubble; meaning, it would not be the matching cosmic feminine to the Infinite Light (based on the Chabad notion that it takes the highest light to suppress light - which is what the tzimtzum is). It would end up being a lower level within the already existing tzimtzum bubble.
Can there be a reality of a tzimtzum plus something to create the necessary difference for there to be a second tzimtzum in the Infinite Light? Yes, but everything feminine in the Infinite Light already went into the tzimtzum bubble. All that’s left to add on, is from the cosmic masculine aspect of the Infinite Light. Such a state actually does exist. It exists along the progressive stages of differentiating out the cosmic feminine from the cosmic masculine. Since, the differentiation does not happen all at once, conceptually there are stages along the way. Kabbalah calls these stages, the “Tahiru Illa’ah” (the Celestial Brightness). However, as long as there are aspects of cosmic masculine mixed in, the cosmic feminine is not polarized enough to become the matching cosmic feminine to the Infinite Light. Her feminization is incomplete. She’s not yet the tzimtzum bubble discussed at the beginning of the Lurianic work “Etz Chaim”.
So based on the above it seems to me that there is only one tzimtzum bubble. Firstly and primarily because only one entity can be formed from all that’s feminine within the Infinite Light. There’s nothing left to form another one with; certainly not on equal stature. Secondly, no exact duplicates can exist in spirituality because of how space functions on that level and since the tzimtzum bubble is the first expression of empty space, some rarified notion of space certainly exists there.