The human eye can perceive light. But only when it has a wavelength between approximately 380 nanometers (seen as violet) and 750 nanometers (seen as red). But these light rays are only a small fraction of the very broad spectrum of rays that exist, from 0.0001 nanometers in wavelength to a full meter. This covers Gamma rays, x-rays, ultraviolet, infrared, microwaves, and radio waves — none of which the human eye can perceive.
But this is not a science lesson — what does it have to do with Geuloh?
We will see that it is a basis for understanding how the Rebbe can say that the Geuloh is here, all the end times have passed, and yet we remain in golus. On the face of it, there is no logical basis to say that something co-exists with its opposite. Geuloh is the opposite of golus. If we have one, we perforce do not have the other. But let us look at what the Rebbe writes in the maamor of Kuntres 15 Menachem Av 5751 which opens with the words “An end was set for the darkness” (“Keitz sam l’choshech“) (originally spoken by the Rebbe on Tisha B’Av (nidcheh) 5724, twenty seven years earlier).
In section 9 of the maamor, the Rebbe describes the end (“ketz“) of the darkness of golus, which is brought about by a revelation of a new aspect of light (“ohr chodosh“). This aspect of light has no connection with the world, and thus it is capable of completely nullifying the darkness (unlike the aspect of light which illuminates the worlds, which can only “push away” the darkness, but cannot nullify it.) The Rebbe writes:
We must understand, seemingly, […] in the future Geuloh the darkness of golus will be nullified, because then there will be a revelation of a new light above connection with the worlds. However, the world itself (as it is in its parameters, including the revelations that are connected to the worlds) will remain in golus, chas v’sholom.
The Rebbe is saying that the Geuloh is a revelation of a new light that, seemingly, cannot be perceived or grasped by the world since this light is completely beyond any connection with the world. In other words, the Rebbe describes a Geuloh (=revelation of the new light) where the world remains in golus! To use the example of the light-waves: even if someone will direct a tremendous burst of infrared light in your eyes, you won’t even blink because the wavelength of infrared is beyond the realm of human sight — your eyes are simply incapable of perceiving infrared light no matter how strong it might be. The light is shining, and you will remain in darkness — Geuloh is here yet you are in golus!
In other words: the light of Geuloh is in fact here, but it hasn’t penetrated your senses yet and thus you remain in golus which means that the true and complete Geuloh didn’t happen yet.
The Rebbe introduced this concept with the word “seemingly”, which means that this won’t be the end of the story. And the Rebbe continues:
Thus, it is understood that even though the nullification of the darkness of golus comes from the essence of the light, higher than the light which illuminates the worlds, nonetheless, the Geuloh will be (also) in the parameters of the world. This is because the revelation of the essence of the light that will be in the future Geuloh will shine in a revealed way also in the light that illumines the worlds, and through this — in the worlds [themselves].
A big relief! Seemingly, the worlds could remain in the darkness of golus even when the light of Geuloh is shining. But, in fact, this “new light” will also illumine in the worlds, as described. We might think that by writing this, the Rebbe is simply uprooting the “seemingly”, telling us that it is not part of the equation at all. But, in the following (and final) section of the maamar, the Rebbe explains how the “new light” will shine in the worlds (which “seemingly” is not possible, since it is beyond connection with the parameters of the worlds):
…also the nullification of the darkness that will be in the future Geuloh will be in the world in its inner dimension (“b’pnimiyuso”). That even though the nullification of the darkness that will be in the future comes about because of the revelation of a new light which is beyond connection with worlds, nonetheless, the world will be a vessel also for this light. And through this will be fulfilled the intent for a dwelling place for Him, may He be blessed, in the lower worlds, that the lower (within its own parameters) will be a dwelling place for His essence.
The key words here are that the nullification of darkness “will be in the world b’pnimiyuso” — meaning that it will not be obvious, rather you will have to look for it “b’pnimiyus”, and “the world will be a vessel also for this light”. This means that it is not “automatic” that the light of the Geuloh will also illuminate in the world (and automatically nullify the “seemingly” problematic “golus amidst Geuloh” issue) — rather, it comes about through our avoidoh. Not only do we have avoidoh which draws down and reveals the “new light”, we also have an avoidoh which is to make ourselves (and the world) a vessel for perceiving this “new light”, and an avoidoh to “open our eyes” to this new perception.
(At the farbrengen of Parshas Mishpotim, 5714, the Rebbe told a story of the Rebbe Maharash taking his son (the Rebbe Rashab) on a tour of the heavenly realms. Among the “sights” they saw was a chossid sitting in a brightly lit heavenly chamber with his eyes closed. The great light in his chamber was generated by the many chapters of Tanya this chossid had memorized. But, despite all that light, his eyes were closed: he was lacking understanding. The lesson for us, explained the Rebbe, is that we need to open our eyes; not just to repeat from memory, but to understand what we are learning.)
If we go back to our example of the light-waves: imagine that a person could develop his power of sight so that he would be able to perceive also infrared wavelengths, and also ultraviolet wavelengths! But even so, he still has to open his eyes in order to allow the light in see what was previously unseen. So, too, by us: we have rectified the vessels to receive the light of Elokus, we simply have to let that light in.
This is the “problem”: the Geuloh is here, the “new light” is shining, and we have even succeeded in making the world a vessel for this light. But as the Rebbe famously said numerous times: we need to open our eyes. The direct way to do this is through learning the subjects of Moshiach and Geuloh.* Tanya explains that the “eyes of the soul” refer to chochma, which is Torah. The Rebbe also alludes to this in the beginning of the maamor:
It is known that every revelation is via Torah (“Torah Ohr” — “the Torah is light”). From this it is understood, that since the nullification of the darkness of the golus is via light, therefore, in order to draw closer and speed up even more the future Geuloh, this is via the study of Torah in the subject of the light. (Footnote 14: in addition to the fact that Torah in general is light, in particular Pnimyus Hatorah — via the study of Torah in the subject of light this is brought about even more so.)
To summarize: The light of the Geuloh is inherently beyond our grasp, nonetheless we can make ourselves and the world a vessel to perceive it as it shines within the familiar light of this world. However, this will be “b’pnimiyus“, and in order to open our eyes to grasp this new light we have to open our eyes — via Torah. Via Torah, particularly Pnimiyus HaTorah, we can grasp the inner dimension of what we see in the parameters of our world* and identify and perceive that the light of Geuloh is shining there. But until then, until we bring in the light of Pnimiyus HaTorah, it is possible that we can remain in the darkness of golus (b’chitzoniyus) even as the light of Geuloh is shining full force!
* As the Rebbe says in Dvar Malchus parshas Chukas: “Through understanding Pnimiyus Hatorah and the soul of the matter, one is able to see there also the hidden good, even though one does not see this revealed, or one even sees the opposite (the opposite of good).”