Let There Be Light: Laser Weapons, Jammers, and 21st Century Ethical Implications

Rachel Petroff Kessler: All right. Now we can begin, and I can officially welcome all of you in the lobby and all of you on Zoom to the first night of our “New Wars, Old Questions: Military Technology and Jewish Teachings in the 21st Century” Scientists and Synagogues program. Right – oh, you can clap.

First, I want to say a big thank you to the Sinai and Synapses organization. Their Scientists in Synagogues grant program made this series possible. And we really appreciate their funding partnership, and also their thought partnership, in putting this together. It’s maybe an interesting topic for us to pick if we’re going to talk about science and religion. I feel like you could think of a lot of things to discuss, and military technologies and science related to those things maybe does not come to the top of your list. But we thought it was maybe an interesting opportunity to take advantage of our positioning and the work of, it turns out, lots of our members and lots of other people who live in this area, to really do some learning on a really interesting and not so simple topic.

So, before we turn things over to our scientists of the evening, I want to offer us just sort of two Jewish texts that we might hold as we move through this series, right. I’ll say it first, same thing I said, if you came to our Shabbat Lunch and Learn, which was meant to sort of prime your palate for this – if you are hoping to walk away with a clear answer on what Judaism says on, like, what to do with all these things, I’m going to just disappoint you right now. And you can work through those feelings for the rest of the class. (laughter) Really, what we’re doing is sort of trying to open up some of our texts and the values of our tradition, and hold them in conversation with the science and the technologies that we’ll be learning about.

Right. So first, famous quote, you’re probably familiar with said by the prophet, namesake of our congregation, “They shall beat their swords into plowshares, their spears into pruning hooks; Nation shall not take up sword against nation, they shall never again know war,” right. We are a people who yearns for peace. We pray for it all the time. Right? “Shalom rav al Yisrael amecha,” “Oseh shalom bimromav, hu ya’aseh shalom,” right? We want peace. This is the hope for the future, right? This is the vision that our tradition holds. But a Torah-stated principle, “if someone comes to kill you rise and kill him first.” Right? This comes from Sanhedrin, rabbinic text, many years later than the Torah, but early, like 200 – 500 CE, a long, strong sense that this is the world that we are in now. And sometimes it is dangerous. And if danger approaches you, you have a responsibility and obligation to do something.

All right, Gary Heiligman, everybody.

Gary Heiligman: Okay. Good evening. I’m the lay member of the team that’s running this with Rachel, and I’m very pleased this evening to introduce Dr. Zachary Epstein. Dr. Epstein received his PhD in laser physics from the University of Maryland three years ago, and been at the Applied Physics Laboratory, where he is a senior professional staff who works with lasers in the military context on a daily basis. And so it’s with great pleasure that I welcome him to talk about lasers, jammers and 21st century technology and its relation to Judaism.

Zachary Epstein: So thank you to Rachel and to Gary and everyone who came here today and the organization Sinai and Synapses for helping to organize this as well. It’s really [great] to be here in this in this lobby with everyone that on a busy weeknight – a cold weeknight as well – came all the way out here to learn Torah and to learn science, and it’s a very holy group, so I feel very, very fortunate to be here.

So there is a quotation here – identifying the source of this quote will be your trivia today.

“From this entity which was like a tiny, narrow point – void of any matter, came forth everything in the entire world.”

So does anyone know, is this the Big Crunch? Is it the Big Bang, The Big Short or the Big Freeze?

So the consensus seems to be the Big Bang. So actually, this is from a classic commentary on the Torah by Nachmanides. (laughter) This is by the Ramban Nachmanides from the 13th century, a famous, well-known rabbi.

And so the question is, where from did the Ramban know this? Was it perhaps the society around him? So as it turns out, what society believed, from all the way in the BCE, until, really the 20th century, everybody believed in temporal infinitism, which means that the way that the world is and the universe is, is the way that it always was. If you go back in time, you would see exactly what you see today. And as you continue to move forward in time, you would also continue to see a stable universe exactly the way it was.

And it turns out that people very much thought lowly of the Jews for this reason, for the Jews believing that the world came from a point, that the world had a beginning. We look around, we don’t see that there seems to be a beginning in the world. Things seem very consistent. And so we received the Torah at Mount Sinai. And Sinai is the same word as “sinah,” as “hatred.” So the sages say that it’s going to be the case throughout all of history, that there should be an inexplicable hatred of the Jews in the world.  And we saw it in the 1800s. We saw it in the 1900s. We saw it in the 2000s, even today. So these sages sure were right – and also in the time of the Ramban, people thought that it was crazy for him to say such a thing.

And another question will ask is: “From where does the Ramban know this?” If you would read the Torah just word-for-word in the beginning, if we would try to translate “In the beginning, God created…”, or the beginning of God’s creating of the heavens and the earth – it doesn’t say anything about a “point.” So where did he get this? If you and I were back in that day, in the 13th century, if we were going to write a commentary on the Torah, and we were going to write comments about the Torah, you know, we wouldn’t think to say such a thing. So the question is, where did he get this? And so the answer is that when we say “commentary” in English, we mean a person has our own thoughts and ideas, and we put comments on top of something. But the Hebrew word for commentary is perush, which means to take something and to open it up and to reveal what’s inside. So the Ramban, because he had such a deep knowledge of Torah, was able to look at the beginning of Bereshit and to come to this conclusion about the Big Bang.

And so before I speak – it says “Let there be light” in the Torah, because I’m a physicist, in optics and in laser physics, so light is something I think about very much, perhaps too much. When the Torah says “Let there be light,” the question is: What is light? When the Torah says “Let there be light,” what does it mean? Is it just light photons? And so, this is going to have multiple layers, and I’ll explain why – in the Torah, really, there have to be many layers. We learn two things about it. One is that the Torah comes from an infinite Creator, and it’s supposed to enable us to live a life that is going to be a godly resemblance of the Creator. And so if we’re going to resemble an infinite being with something such as the Torah, so it ought to be fairly deep, to have some sort of infinitude within it.

And secondly, we learned that when we learn Torah, we’re connecting with, so to say, the mind of HaShem. Our mind connects to a greater wisdom. And so therefore, if it’s reflective of the mind of HaShem, it should be very deep. King David, regarding the Torah, regarding Hashem, says, “O Lord! Your thoughts are very deep.” The question is, we look around society, and some people see that the Torah is something very deep, and some people feel that it’s trivial or superfluous. There seems to be a wide range of different opinions on the matter. And so you’ll find a trend when you approach this matter, and it’s a verifiable trend. It’s a trend referred to in d’varim; all the way back, it was predicted. It says “For it (the Torah) is not an empty thing from you, for it is your life.” And the Midrash says, regarding this, “For it is not a trifling thing. And if it seems trifling, this is from you.” Meaning, that the emptiness comes from within the person.

We find this very interesting trend in our personal lives, and also in our interactions with others, when a person hasn’t learned very much about Torah. So it seems very simple, nice messages from sweet people. And the more a person learns, I find, and we find if, you know, consult the Rabbi Rachel and then others, that the more a person learns, the more person realizes how deep and layered the Torah really is, and how much there is to learn about the Torah.

So this is an image of a Young Double Slit Experiment. I’m going to speak a little bit about “What is light?” So when we think about light, you have some lamps up here. So what’s happening when the light comes into our eyes? So it seems to be that it sends out photons, it sends out little light particles, and they go to our eyes. And our eyes send signals to our brain, and our brain processes, and we realize that it’s bright, and it’s light. But light is not only a particle. The Young Double Slit Experiment was the first experiment that really showed that light is a wave, and [that] there’s particle-wave duality. So he took a flashlight, and covered it with a light filter, just so that he had only one color. And he sent this light through two slits, through a board that had two slits in it. So you would think, “Well, what comes out on the other side, there’s going to be light from one slit and light from the other slit.”

But that’s not what he saw. He saw that on the other side, in the middle between where the two slits were, there was a bright streak. And he found that as you go further out, it gets dark. And then as you go further out on both sides, it gets bright again. You go further out and it gets dark, you go further out and it gets light again. Very strange, very interesting. And that’s because light is a wave. So if you have this sinusoidal wave, this is the electric field as a function of time or of space. This is a way to represent light.

And so the peaks of the top of the blue wave are aligned with the peaks of the yellow wave. So then we see that they add constructively, it’s taking one and one and adding it. And so you get a larger wave, and you get a lot of light, you get a brighter spot. But if the direction is such that the blue, and the peaks of the blue, are located at the troughs of the yellow, it’s like 1 + (-1) = 0, and you get nothing – you get a dark place. And so this is what’s happening due to what they call superposition, which was a property of waves. Now, if you would reduce the energy in the light, in the flashlight, or you would put a bunch of filters just to make it really, really not very bright, what you would find is that every once in a while there’s a photon — pop! — it goes through a slit, and then it shows up in one location, at one point on the detector. And then pretty soon another photon comes through, and pop!, it shows up at another point in the detector. So very clearly, light is a particle. And if you would allow this process to continue, and you would record where every photon is hitting on the detector – so slowly, if you put all that together, you would see something similar to these, the bright spot in the middle of the bright spots and outside. Those are the locations where each individual photon is going to. So, somehow it seems to be [both] a particle and a wave.

Now, physicists do not like that very much. Jews love it, actually. (laughter) So we say, “Or haTorah.” We have this phrase “Or haTorah,” which means “the light of Torah.” So why does King Solomon – he says this in Proverbs – say that “the Torah is light?”

So the simple analogy is that we live in a world that’s full of darkness. There are so many challenging things occurring in the world – so many problems in the world. We can try to learn from animals to find light in the darkness. But sometimes animals behave altruistically. And sometimes they eat one another alive. There are so many perspectives and ideologies, systems of values, definitions of what is good and what is bad. And there’s no instruction guide to illuminate for us what’s important, and how to live our lives, if we’re just looking at nature, unless we were, perhaps, very discerning. Until the Torah – which lights up the darkness and shines a path for us. It shines a path of righteousness and of truth, and it has changed the entire world and continues to change the world. So in the eyes of King Solomon, this was why the Torah was light, and his words continue to be so relevant today.

And so now we’ve spoken a little bit about light, a little bit about the Torah, and described the structure of light, that it’s a wave and a particle, one question would be: “Well, what is the structure of the Torah?” And light and the Torah are related by King Solomon, so perhaps their structure also corresponds.

So in the Torah, the first thing that we have is the Written Torah. We think of the Torah – so we think of the Five Books of Moses. You put it into a Torah scroll, you wrap it up, and that’s the Torah. And yet when you go to the Torah study at synagogue, after they bring something from Deuteronomy in, from Genesis – then they bring something from the Talmud, and then Ethics of the Fathers, Pirkei Avot, from the Mishnah. And then they bring the Midrash. So we should say to our Rabbi, “Well, we’re going home, or you’re going home, because this isn’t the Torah, the Torah is the Written Torah.” But rather, you find that not only is there the Written Torah, but in addition, there is the Oral Torah, which enables us to understand what is written within the Written Torah. And so while the structure of the Written Torah is very finite, just like a point, it’s very definite. We can point to a Torah scroll and say, “there it is,” and they’re all the same.

So similarly, when we consider the Oral Torah, which has all these different opinions, and deep, lively discussions that still happen today, you know, in all of the study halls, you know, two students studying together passionately, even when class doesn’t require it, debating and discussing. So there are very many truths and many perspectives within it. And so first we would say, “Well, this is very much like a wave. A wave has superposition, it’s the superposition of many truths.” But we might have a problem, to think, “Well, how could it be that there’s different opinions within the Oral Torah? When we look out at the world, there’s a certain truth, and that’s the truth.” So it’s very much like a diamond. If we were looking at a diamond from one angle, we would say, “Ah, this is what the diamond looks like.” But another person would look at the diamond from another angle. And he would say, “No, it looks like this,” because it’s the finitude of our minds. But really, the diamond is a diamond, there are different ways to look at it. And it all is the diamond. So too, with the Torah, all of these different perspectives come together to create the truth in a superposition. And so to highlight all of these different ways, add together and create what we observe as light.And just a final point regarding this is that it’s not only that the structure is related in such a way, but the issue that physicists really have is [that] we want light to be a particle. And ultimately, it turns out that it’s a wave. We want light to be a wave, and it turns out that it’s a particle.

So we find in the Gemara, in Shabbos, in the Talmud in Tractate Shabbat, that there is a potential convert. And he went to Shammai and he said, “I want the Written Torah, but I do not want the Oral Torah. Will you convert me?” He said, “I want to light to be a point. I don’t want it to be a wave.” The Shammai sent him out. He said, “That’s not the way the Torah works, and that’s not the way light works.” So he went to Beit Hillel. And he said, “I want to learn the Written Torah tutorial, and I want to convert, but I don’t want Oral Torah.” So basically, Hillel said, “Here, come sit down with me.” You know, this was the greatest scholar in all of Israel, in addition to Shamai. And he sat down with the convert to learn the Aleph Bet. And he teaches him an Aleph and says, “This is an Aleph,” he teaches him a Bet and says, “This is a Bet.” And he says, “Come back next week, we’ll continue.”

So the potential congregant comes back in the next week. Beit Hillel points him to a Shin and says “this is a Bet.” And so the congregant is very confused. He says, “But last week, you told me that this was an Aleph, this was a Bet.” And [Beit Hillel] explains that without the Oral Torah, if all we had was the writing in the Torah, we don’t know anything, we don’t even know what a letter is. So he says, “You cannot have the written Torah without the Oral Torah.” You want light to be only a particle, [but] it really is also a wave.

And similarly, we have two have Halachas, Jewish laws, that illuminate this as well. So the Oral Torah, it’s not supposed to be written down. When you write something down, it becomes very defined and finite. And so for many years, it was entirely oral and spoken for 1,000 years. And then comes the destruction of the Second Temple. And it was acknowledged that if we would not write something down, we would lose the whole Torah. We were being dispersed to all of the different nations, to where we are today. And so what they did was they wrote it very tersely, into the Mishnah. But not so much, because it’s not supposed to be written. And later on, they realized that that was insufficient, and wrote it in a little more — it’s still very terse, but a little more — into the Talmud. And that’s what we discuss very often today. And the reason that it can’t be written into a book, the oral law, there’s a Jewish law that it has to be oral. It’s because people want for light to be a particle, but no, really, it’s a wave.

And similarly, when it comes to the Written Torah, when we have the Written Torah, we would think, “Well, maybe we’ll make it oral, you know, maybe we will speak it by memory,” it turns out that there is a Jewish law, which tells us that with the exception of certain things like kri’at Shema, the reading of the Shema, a person is not allowed to recite the Torah by heart. You have to have the physical written Torah there. So if on the other side, you want for light to always be a wave, so you can’t. It has to also be a particle. So the structure is very similar in this way. And just to mention, “eilu v’eilu, divrei Elohim chayim,” the words of the Talmud, which say that Beit Hillel has his opinions, and Beit Shammai has his opinions. They apply the same Oral Torah, but they get different results. When they apply it to the Written Torah, they come to different conclusions. And we say that both of these are the words of the living and eternal God. And this is the principle of superposition. This is occurring in the oral law. And it’s no coincidence.

And so those are some of the parallels. So the question now is, “Why do physical light and the Torah, which is referred to as light – why do they have so many parallel, some of which include modern scientific theories, like particle and wave duality, which the sages of old were not involved with?” And similarly, the Ramban and Chazal teach us. And when they say Chazal, it’s translated to “the sages.” In English, it would “wise ones of blessed memory.” But when we talk about sages, you know, we think cute old men, or, like, a course of ancient philosophy in college – it’s very difficult to relate. But here’s what the sages say about the sages. Rabban Gamaliel, in Berachot, calls them ba’alei t’risin, which means “shield bearers.” So Rashi explains – he has a famous commentary on the Talmud, and on the Torah, he was an unbelievable scholar – he explains that “Torah scholars are called shield bearers, because when they argue and dispute in the beit midrash, in the study hall, they battle each other in Torah, like warriors wielding shields.”

This is something very rigorous, and something that’s really a war. It’s something that people fight about very strongly, because what we want is to get to the truth. And similarly, it’s written in Ethics of the Fathers and Pirkei Avot (2:10) that reveal it, as I said: “Warm yourself by the fire of the sages. But beware of their embers, lest you be burnt, for their bite is the bite of a fox, their sting is the sting of the scorpion. Their hiss is the hiss of a serpent. And all their words are like fiery coals.” So these are the sages, when we say chazal. They say that God looked into the Torah and created the world.

So the Torah is saying in the Midrash, is that it’s not only a book of wisdom, but rather, it’s the code, the blueprint, from which the world was created. So it’s like the blueprint of a house. If we look at the blueprints of the house, we might not know exactly what it is. We might be able to have different interpretations, as far as “How do we understand this? Does this does this translate to a door?” Now we’re looking at every blueprint, and we’re going to say that this is the door? Or maybe it’s a window. So there’s different code, there are multiple ways to define how to translate a code into reality.

So the written Torah, we understand, is the blueprint or the code for creation. It’s not a separate thing or a book of wisdom, but creation itself is within the Torah, and the Oral Torah, then, contains a set of rigorous tools to decipher the Written Torah. So in Rabbinic Judaism, we have the Oral Torah. And you’ll know that because I can show that really, the Torah is such a code, because the Torah is a code in such a way. And it’s so terse. So when we advance divergent interpretations, this happens throughout Jewish history, and these interpretations often lead to a lack of Jewish cohesion. And so the first time we see this was in the case of Korach and his followers. So he challenged Moshe himself. He said, “Moshe, your interpretation of the written Torah is improper, here’s my interpretation.” And he and his followers, they ended up falling into a pit in the earth – had a very unnatural natural death.

And so we would think he was well-intentioned, but the sages teach us that really, he had an alternative motivation. It was that he wanted to be accepted into the ranks of leadership. And so the lesson for us all, and when we want to have different positions in situations of leadership, is to really think about: is it that we’re going to do the best job being a leader, or do we want the honor of being a leader in certain ways?

And there were the Tzedukim, very similarly, influenced by the Greeks in ancient Israel. The Tzedukim felt that the Greeks had a superior culture. And they wanted to be like the Greeks, they wanted acceptance. There was a procedure where they would take the bris and they would do a surgery on it in order to stretch the skin so that when they would run with the Greeks, in doing athletics, the Greeks wouldn’t know that they were Jews, and they wouldn’t know that they were circumcised. So this was how much they wanted to be Greek. And so therefore, they were susceptible to these alternative interpretations. So they became the Tzedukim. And they split off and created a tremendous division within the Jewish people that spoken about throughout the Talmud. And the Kara’im, in 9th and 10th century, in the Islamic Caliphate; they were very much influenced by the golden age of that culture. And so they also were susceptible, and they took their own interpretation. And now, you know, they split off, and there’s a lot of division and difficult feelings, hurts, and ultimately, there’s very few left.

And in Germany, in the 19th century (correction: 20th), many Jews were among the secular biblical critics. And when we read, you know, any German Jew from the 20th century, besides maybe one or two that we’ve heard of, if we see their writings, interestingly, you would see that the way that they describe the Jewish people, they spoke with the identical anti-Semitism, as Jews, as the German society surrounding them. And specifically, in the 20th century, it was a very particular type of anti-Semitism. And similarly, the Christians – they were also influenced by the Greeks, the early Christians. And so they too, were susceptible to be connected with Yehuda ben Prakiah’s failed student, and they followed after him, and they separated totally from the Jewish people and became the Christians.

So what we find in Torah, we see that somehow this propagates throughout all of history. And this is because the Torah is a book of stories, it tells us the precedent and sets the precedent. It’s a predecessor for everything that comes forth. So when we look in the Torah, and we learn from the Torah, we can now understand everything and see the patterns that happen within society, and know how to act in the future.

And so now that we’ve said that the physical world is, at first, one of the challenges with alternative interpretations like this, is science. So the Christians had a very particular interpretation. And within that interpretation, it’s said that all the planets, and the Sun, revolve around the earth. So everyone’s familiar with Copernicus, and Galileo, that the Church persecuted for science. And this very much leads to this conception that science and the Torah are incompatible, science and religion are incompatible. And indeed, the early Christians, as you know, and the Church, they weren’t compatible. But the Oral Torah, fortunately, is compatible with science. So I’ll give you an example. We read in the beginning, “Hashem created the heavens and earth, and shamayim v’aretz.” So some of these different interpretations – we want to say it means “In the beginning, God created the heavens and the Earth,” or “the sky and the earth.” Well, see, the only problem is that on the second day God created light. And we know today in science that light came before the Earth. So fortunately, as Jews, we understand that firstly – some say it’s in God’s creating the heaven.

But even regardless of this, what is the heavens? Shamayim – does this mean the sky? So if we look at the word shamayim, you understand that it’s a combination of an aish and mayim, a combination of the words for “fire” and “water.” And what we learned from that is that it means the spiritual world. Because in this world, fire and water don’t mix. If you take fire, and you take water, fire is going to steam up the water and it’s going to evaporate and disappear. And if you would take water and put it on a fire, so you extinguish the fire. So therefore, in this physical world, aish and mayim do not exist. So therefore, shamayim, as we understand it in oral Torah, to be in the habit, the spiritual world, and the sky, the spiritual world. And so then the aretz would be the physical universe. And indeed, we know it’s not the Earth, because several, several days later, we have the Earth.

So what we see here is that the physical world is encoded within the Torah, such that everything physical is a manifestation of something spiritual. And I’ll give a couple examples, because it’s a very abstract concept. So taking non-kosher animals – there’s a common misconception that pig is not kosher because it has bacteria, and the person would eat pig and get sick back in the day. Whereas today, you know, “We can cook it, so it’s no problem, totally kosher.” So this concept, we can think of why people like this concept, but it happens to be that the Torah doesn’t say such a thing. It says that non- Kosher animals are non-Kosher – pigs and shellfish – because the Torah says they’re not Kosher. And it says that these things are spiritually damaging, you know, for a Jew to eat. It says that it’s going to affect a Jew’s ability to connect with God. And so this is the spiritual reality that the Torah says. So when it manifests itself into the physical world, it’s not a coincidence that we see that pigs have bacteria. And we see that shellfish have bacteria. And that, physically, that something that might be spiritually unhealthy manifests itself in a way where the physical reality reflects the spiritual reality. And so to physical light, we have a light. We know what light is, but it’s merely a manifestation of something spiritual.

So I’m not going to speak about this slide so much, but we’re talking about the layers of Torah, and this is going to become relevant to the next couple sides. We have Pshat, the simplest layer, the surface layer of the Torah. Just to read it, word by word, just to understand what the Torah’s talking about.

The second layer that our tradition speaks of is Remez. It’s like a hint.

And one layer deeper, we have Drush, contextual, non-contextual, moral and philosophical explanations, and Halachic discourse.

And the fourth level is Sod, Kabbalah, the hidden or secret meaning. So Jewish physicists observe striking parallels between the hidden part of the physical world, in other words, in science. Many of them write beautifully these topics, among them Andy Goldfinger here in Maryland, Yosef Sebag, Gerald Schroeder, Chaim Presby, Aaron Schreiber, Avi Rabinowitz, Yehuda Levi, Harold Gans. These are just a few. So there’s something going on, that Kabbalah and the Torah, science and the Torah, have had such parallels. And the reason is because the physical world came out of the Torah. So they should reflect one another.

So now that we’re talking about “what is light?”, so first there’s physical light – so after the creation of shamayim v’aretz, at the beginning, so first, we have tohu vavohu, the Torah says. Which means that first we have tohu, which is complete and utter emptiness. And then we have vohu, which, the Ramban explains, is the four elements of the universe – meaning we have matter and antimatter, positive charges and negative charges. Similarly, we have the four fundamental forces of the universe. We have the magnetic force, gravity, with strong force and weak force. And through these forces and these particles come the four types of matter. Because of these physical principles, we have gas, we have solid, we have liquid, and we have plasma. And so we understand, from the great Bal Shem Tov, in the 1700s, he says that the primary goal of religion, the greatest goal of the Jewish people and every individual Jew, is to unify the four letters of Hashem’s name, YHWH. We can talk Kabbalistically about what this means. But he says this is the greatest goal of the Torah.

And I heard of a friend who had a grandfather, an old Moroccan man, who everywhere he went, he would mutter something. He would tie his shoe, he would mutter something. He would open the bathroom door, he would mutter something. And his grandson asked him, “what are you saying?”. He said, “l’sheim yichud HaShem,” “for the sake of the unification of the Holy Name.” And this comes up very often. So this is the greatest goal, says the Bal Shem Tov, of Judaism. And as it turns out, the greatest goal in science, the greatest goal of all physics, is to take not the four letters of HaShem’s name, but the four physical forces, and to unify them into a unified field theory. So interestingly, the greatest goal of the Torah, the Jew, and the greatest goal of science, are the same.

So Torah is also spiritual light. We learn that King Solomon’s Proverbs, “For a Mitzvah is a lamp, and the Torah is light.” So a Mitzvah is a vessel for us to receive and to release light. And the Torah he calls light.

In defense, what are the answers to jammers? So in defense, filters are the preferred strategy both for jammers and for decoys. So if someone tries to jam you and puts a bunch of light into your attack, but if you have a filter, to be able to filter out what they’re sending with the jammer, or you know, what their jammer light looks like, and [knowing] what you’re supposed to be looking at, you can get rid of the jammer light if it’s not too strong. If it’s too strong, you have no actual chance. 

And similarly, [with] incorrect targeting, you have decoys. But if you have a filter, you can say, “Look, I analyzed this object and it’s not accelerating. It’s not is the missile, this is the missile, this is what’s accelerating.” And so in defense, filters are the preferred strategy for dealing with jammers, and with decoys. And so similarly, we learn – this is something that was predicted back in the days of Deuteronomy. Moses says, “Judges and officers you shall place at all the cities at your gates” – it’s in Shoftim. And so the Siftei Cohen says, “the human body is a city with seven gates, seven portals to the outside world – two eyes, two ears two nostrils and a mouth. Here too it is incumbent upon us to place internal judges to discriminate and regulate what should be admitted what should be kept out, and officers to enforce the judges’ decisions.”

And for every person this means something different. As Jews, we’re not a society that believes in censorship. And at the same time, we’re not a society that believes everything that comes in, we’re going to indiscriminately and uncritically consume. And so as Jews, we stand somewhere in the middle. There are very few things where maybe we won’t be exposed to. There are certain places that you can’t go, we can imagine. But really, when it comes down to it is that we as individuals have to be empowered to choose what we want in our lives, and what we don’t. The people around us influence us. Do people make us feel good or bad? Do they make us better or worse people? How do we interact with them? What interactions? What activities make us feel better and more connected and more involved in life, and which things make us feel very down?

Similarly, the things that we’re exposed to – say, it could be a television show that makes us feel very good, and excited, and we interact well with the family and their children. It could be another one where there’s a character, who’s the main character, that we feel attached to, who speaks in a way that’s not appropriate for a Jew to speak. And so it can be, for us to watch this character, that maybe a person finds if they spend a lot of time watching a character speaking in a certain way, eventually “I’m going to start speaking this way.” We’re human beings, we’re very susceptible to influence. 

And similarly, someone might listen to a radio show. And the person speaking is very angry about the matter they’re speaking about. And we understand that in Judaism, with most things we want to be in between. We want to be generous, but we also want to be careful about not giving too much outside of our family. We have to be active in things, but we also need to know when to rest. All the different character traits – we don’t want to be too strong, we don’t want to be too weak. We have to find the middle ground in all the character traits, says the Rambam. But the one thing he says is that when it comes to anger, that’s a character trait that a Jew is not supposed to have. And so a person who listens to someone speaking angrily about a certain topic, a person, naturally, when that matter comes up, is going to feel angry about it. Perhaps there’s another person who talks about it very well. 

And things like this, you know, to everyone each their own, everyone has to – we think about it in our own lives. What are the things that we filter out and what are the things we want? What are the things we take in? We can think critically about the things that we’ve decided we do want to take in also.  

And so on that note, I want to turn to my favorite field, of nonlinear optics. And I’m going to share a little bit about what is nonlinear optics, and take a whole different turn and say what can we learn from nonlinear optics. So a CO2 drive laser is a good example, but really the concept of nonlinear optics is that you take some sort of laser power, something that changes very quickly in time, [such as] a short pulsed laser, you can get a lot of energy, in a really short pulse, or you can take two lasers at different frequencies and beam them together in order to create a short pulse as well, in a sense. 

And so you take this light, and you pump it into a nonlinear medium. So what’s interesting is that every medium, really, is nonlinear. When you send a light through a prism – say, white light, you send it through a prism, it separates the colors, red to green. But it didn’t create the color, it just dispersed the colors into different directions. So that’s linear optics. Nonlinear optics is when you hit the prism so hard that you cause the electrons to do all kinds of crazy things, nonlinearly. And they produce different colors of light, with all sorts of very interesting nonlinear effects that have many applications in defense, and in medicine, and in many things in the world. 

In one application, say, [is] if we want to use the laser light for remote detection, or as a laser weapon. So you take the laser light, and you focus it down real good on the material, where it’s reflected at high intensities. And you spread it out and you send the beam off to a target for remote detection, or whatever your application is. So nonlinear optics, it’s interesting – it existed all along, but usually only interacted with linear optics. You have to hit a nonlinear medium so hard that we cause these existing properties of the material to manifest themselves. And they always existed, but we just didn’t know we needed to hit it with a lot of light. 

Similarly, this is something that relates to Mussar. I don’t know if there are Mussar classes here. So Mussar is a traditional field of Jewish study that became very popular in the 1700s and 1800s, with Rav Salanter and others. And the idea is to look at Torah and really think about what are our characteristics. We learn certain principles about how we should be. What does a Godly person look like in the Torah? And so we analyze ourselves in very careful, very particular ways. And we realize things about ourselves that we didn’t even know existed. And it turns out often that these things are manifested in our everyday life, and we influence them through Mussar. We have the opportunity to learn about these things, about ourselves, and to change them and our lives in a beautiful, Godly way. 

And various ethical questions that come up. These are very complicated Halachic questions. Laboratory eye damage – what’s the level of risk? Who pays the damage if someone’s eyes get damaged in the experiment? When you use lasers, there’s back-scattered light. And also can you use lasers to blind your enemies? Is that humane? Lasing down a hijacked plane – what if there’s people on the plane? Are they innocent or are they a rodef? When you’re considering approaching someone to kill them, did you come to kill them? And so, I want to make sure there’s at least a few minutes for some discussions, questions.

So we’ve spoken a little bit about the depth and the layers of the Torah, we’ve talked about what is light, “For mitzvah is a lamp, and Torah is light”? (Proverbs 6:23) We’ve spoken about wave-particle duality, how the properties of the Torah and the properties of light, in tremendous ways, parallel one another in ways that only modern science has discovered. We’ve looked at the steps of creation, of what that means. We’ve looked at lasers versus ordinary light, a light source absorbing and amplifying a structured beam for interactions which resembles the original source. We found that in a sense, we are like a laser source. We’ve looked at the role of lasers in OrHa Torah, in ensuring the bright future, the light, of the Torah. We’ve looked at countermeasures and ethical and moral parallels. We’ve looked at laser jammers, and laser generation of probes and jammers, and nonlinear optics and ethical/moral parallels. And just briefly, [we’ve been] touching on some different Halachic questions, which I encourage those who are interested to see what’s said about them and have discussions here. 

Rachel Petroff Kessler: Zach, thank you so much. First of all, I want to say that I deeply appreciate the plumbing of a metaphor, and I feel like I have a much richer sense of what we can mean when we talk about, right, the light of Torah being a light to the nations. I’m really going to be sitting for a while with this sense of the duality of light, and how that speaks to us as a people. And it’s why we’re so good at comedy – we’re very comfortable with “yes, and,” and the multiplicity of possibilities that might exist out in the world.