‘Brotherhood and Beamlets’  Sukkot 5786

On the holiday of Sukkot, we are commanded to take the Four Species – the lulav (palm branch), etrog (citron), hadassim (myrtles), and aravot (willows) – and to wave them together in all six directions. While this commandment might appear simple, it holds deep spiritual and mystical power. This ritual is deeply symbolic, reflecting unity among the Jewish people, the omnipresence of G-d, and a spiritual harmonization between heaven and earth. To appreciate this more fully, in this essay we will draw a parallel between the Four Species and a modern technological marvel: the Coherent Beam Combining (CBC) laser.

Our Sages in the Midrash [Vayikra Rabbah 30:12] famously teach that each of the Four Species represents a different type of Jew: The etrog has both taste and smell, symbolizing one who possesses both Torah knowledge and good deeds. The lulav has taste[1] but no smell, representing one who studies Torah but lacks deeds. The hadass has smell but no taste, representing one who performs good deeds but lacks Torah. The aravah has neither taste nor smell, representing a person who has neither Torah nor good deeds. According to normative halacha, if even one of the four species is missing, the commandment cannot be fulfilled. Only when all four are taken together, in one bound unit, can the commandment be completed. This is not just a message of inclusion – it is a blueprint for coherence. The Four Species do not symbolize uniformity. On the contrary, they represent diversity within the Jewish people. Sukkot teaches us that unity is not built by erasing difference. It is built by bringing distinct parts into alignment toward a common purpose.

This concept is strikingly mirrored in the world of laser physics, particularly in the design of CBC lasers. What, then,  is a CBC Laser? In the world of optics, lasers are not just sources of bright light. They are defined by their coherence: the degree to which the light waves move in synchrony. In a traditional laser, coherence is achieved by amplifying a single light beam so that all photons travel in lockstep, resulting in a focused, high-intensity beam. But there is a limit to how much power that can generated from a single laser and it might not be sufficient to, say, intercept a mortar shell headed for Sederot. As engineers and scientists pushed the boundaries of laser technology, they discovered that they needed more power than any single laser source could provide. This is where beam combining comes in. In a CBC laser, instead of relying on one powerful laser, light from multiple smaller lasers, called “beamlets”, is combined. Each beamlet is generated separately. On its own, each beamlet is weak and limited. But when all the beamlets are brought together with perfect phase alignment, meaning that they oscillate in synchrony, the result is one single, focused, high-intensity laser beam, created not by a single source, but by a collection of smaller ones working together. Beam combing is not merely stacking beams on top of each other. CBC requires coherence: the beamlets must be carefully calibrated so that their peaks and troughs match perfectly[2]. When they do, their energies amplify one another, creating something more powerful than the sum of its parts[3].

Now let’s return to the Four Species. Each of them, on its own, represents an incomplete Jew. One has Torah but lacks deeds. Another performs good deeds but doesn’t study. A third lacks both. And yet the Torah demands that we combine them. Not just metaphorically, but physically, in our hands. The lulav, hadassim, and aravot are bound together; the etrog is held adjacent to them. And then they are waved as one, in every direction, as a unified spiritual gesture. In this light, the Four Species function as beamlets, individual streams of potential. On their own, they are insufficient. But when brought together with intention, alignment, and coherence, they generate a unified spiritual force that is greater than any individual component. This is not a metaphor for tolerating difference. It is a metaphor for harnessing it. CBC doesn’t erase the identity of the beamlets, rather, it requires their uniqueness, but channels their power into a unified whole. This is the Jewish people. We are not clones of one another. We each have our own path, our own strengths and weaknesses, our own wavelength, if you will. But when we align ourselves with the greater mission – the service of G-d, the pursuit of Torah and the performance of its commandments – our individual energies combine into a coherent spiritual beam that can pierce through the darkness of any situation that the Jewish People might find ourselves.

What happens without coherence? In CBC, if even one beamlet is out of phase, if its light oscillates slightly off from the others, the combined beam loses power[4]. The energy disperses. The signal becomes noisy, scattered, and ineffective. So too in the Jewish community. When we are out of sync, when we allow ourselves to become divided by ego, ideology, or indifference, we lose our effectiveness. Our light becomes scattered. Our national mission is diluted. Our ability to reflect G-d’s light is compromised. This is why the Four Species must be complete. This is why every type of Jew must be present. Not only the righteous, not only the learned, not only the observant. The “aravah Jew”, who appears to have neither Torah nor good deeds, must be part of the bundle. Their beamlet is essential. Without it, the coherence fails. Without it, the spiritual laser cannot form. What matter is not what you do, but who you are.

Let’s add another layer to this metaphor. When we wave the Four Species, we do so in six directions: east, south, west, north, up, and down. Our Sages explain that this waving symbolizes G-d’s presence in all dimensions, and our desire to bring divine unity into every corner of the world. In laser optics, direction matters deeply. A coherent beam must be pointed, focused, and delivered. If we are using our beam to deep-fry a suicide drone, the beam must be aimed with precision. A misaligned beam, even if perfectly coherent, becomes useless. This is the danger of spiritual self-containment. It’s not enough for the Jewish people to be coherent internally. We must also be directed outward, bringing light to the world. Just as a laser is not built to shine inwards but to illuminate or interact with the world around it, so too is the mission of the Jewish people to be a “light unto the nations”, a focused force for holiness and justice.

We live in a fractured world. Politically, religiously, socially, divisions seem to multiply every year. On the second anniversary of the Massacre of October 7, the Jewish People seem every bit as divided as we were on October 6, 2023. The commandment of the Four Species, and the technology of CBC lasers, offer us a powerful message: We do not need to be the same to work together. But we do need to be aligned. We do not achieve greatness by being identical, but by each of us contributing his unique light to a greater coherence.

This Sukkot, as you pick up your lulav and etrog, think of each component as a beamlet, each representing someone in your life or in the Jewish people. Ask yourself:

• Who is missing from the bundle?
• How can I help bring them into phase?
• How can we all align to shine together?

Because when we do shine as one, we don’t just wave branches – we fire a laser.

Ari Sacher, Moreshet, 5786

Please daven for a Refu’a Shelema for Iris bat Chana, Shlomo ben Esther, Sheindel Devora bat Rina, Esther Sharon bat Chana Raizel, Esther bat Hila, Meir ben Drora, and Hodayah Emunah bat Shoshana Rachel.

[1] The Midrash is referring to dates, not to the lulav itself.

[2] This is called “positive interference”.

[3] Power is a function of the square of the amplitude.

[4] This is called “negative interference”.