Free Will and Choice – Lesson 8
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Table of Contents
- The connection between materialism, determinism, and libertarianism
- Chaos and unpredictability
- Epistemic doubt and ontic doubt in Jewish law and in definition
- Ontic room, free choice, and quantum theory
- Rejecting quantum theory as a basis for free choice
- Scales, decoherence, and quantum biology
- Consciousness, collapse of the wave function, and myths
- Philosophical conclusion and continuation of the series
Summary
General Overview
The text raises the question whether a libertarian conception of free will can be integrated into the physical picture of the world, and distinguishes between the non-necessary conceptual connection between materialism and determinism and the factual connection that follows from the laws of physics. It argues that for materialism to be compatible with free choice there must be “ontic room” within physics, and it rejects the attempt to ground such room through chaos and through quantum theory. It concludes that chaos theory provides, at most, epistemic unpredictability, while quantum theory provides, at most, randomness, and is also irrelevant to the scales at which human choice occurs. Therefore, physicalism leads to giving up free choice, and anyone who wants to preserve free choice is pushed toward dualism.
The connection between materialism, determinism, and libertarianism
The text states that conceptually one can be a materialist libertarian or a dualist determinist, and therefore there is no necessary connection between the question whether the world contains only matter and the question whether there is free choice. It argues that people nevertheless connect materialism to determinism and free choice to dualism because the actual laws of physics may impose such a connection. Its goal is to show “room within physics” that would allow free choice within physicalism, and it presents three families of proposals from the literature: chaos, quantum theory, and emergentism.
Chaos and unpredictability
The text argues that the connection people draw between chaos and free choice stems from a conceptual confusion between inability to predict and genuine freedom. It explains that if there is free choice then one cannot predict in advance what a person will do, but inability to predict does not prove free choice, because there may be a deterministic world in which the calculation is too complicated or the information is lacking. It illustrates this with a ball at the top of a symmetric mountain, where tiny deviations and unmeasured wind determine to which side it falls, and with a piece of paper thrown from the third floor whose path cannot be predicted because of the complexity of the winds, while insisting that in both cases “the circumstances completely dictate” the outcome and there is “nothing free” here, only a limitation of knowledge or computation.
Epistemic doubt and ontic doubt in Jewish law and in definition
The text defines epistemic doubt as doubt that stems from lack of information when in reality there is one fixed answer, and illustrates this with knowing whether a boy or a girl was born, and with the case of an agent who betrothed one of two daughters and then both the agent and the father died, so that no one knows who is betrothed even though there is one clearly betrothed daughter. It defines ontic doubt as indeterminacy in reality itself, created when there was no determination of “which one” from the outset, and it brings the case of betrothal not fit for intercourse, when one says, “One of your two daughters, and I don’t care which,” and the example of someone who consecrates “one of them” from among five coins without specifying which one. It states that almost all doubts in Jewish law are generally epistemic doubts, while ontic doubts are pathological, esoteric cases, and presents twilight as, simply speaking, an epistemic doubt: day turns into night at some particular moment that we do not know, while claiming that “ontic” conceptions of twilight are really tied to definitional vagueness in the concept “night,” not vagueness in reality. It explains that a tumtum is an epistemic problem because “inside there is something,” whereas an androgynos is a definitional problem because in reality “everything is clear” and the question is how to define such a creature.
Ontic room, free choice, and quantum theory
The text states that chaos provides at most epistemic room, whereas free choice requires ontic room, in which even with all the information, all the laws of nature, and infinite computational power, the circumstances still do not dictate a single result. It presents quantum theory as the only candidate for such ontic room and explains the double-slit experiment through the history of Young’s experiment in the Newton-Huygens dispute over the nature of light, describing constructive and destructive interference as a wave property that produces a pattern with a central peak. It describes how the double-slit experiment with electrons yields an interference pattern, and that even when “single” electrons are sent, a wave-like pattern emerges. From this comes the idea that the wave function describes “quantum probabilities” that are ontic and not epistemic, by analogy to betrothal not fit for intercourse, where each possibility is “at fifty percent” in the sense of a mixed state and not merely ignorance. It adds that when a detector is placed next to one of the slits, the interference disappears and one gets a particle-like result of two peaks, presenting this as the measurement problem in which “when the teacher is watching,” the particle “behaves itself,” while emphasizing that even then quantum uncertainty remains regarding which slit will be chosen. It describes the Copenhagen interpretation in terms of collapse of the wave function and superposition as a sum of possible states, and presents Schrodinger’s cat as a superposition of “live cat” and “dead cat” until the box is opened as a measurement.
Rejecting quantum theory as a basis for free choice
The text argues that even if quantum theory provides ontic indeterminism, this is at most a mechanism of randomness and not of free choice, because the detector does not “determine” through which slit the particle will pass, but only transfers the system into a state in which the result is determined like a lottery according to the wave function. It states that free choice is a “third state” that is neither determinism nor indeterminism, because choice carries responsibility while a lottery is something that “happened to you,” not an action you perform. It argues that if the wave function dictates a probabilistic distribution of actions, then a consistent choice that deviates from that distribution means departing from the laws of nature, even if the laws are statistical. Therefore quantum theory does not insert free choice into physics.
Scales, decoherence, and quantum biology
The text states that significant quantum phenomena exist at extremely tiny scales, and that biological systems like a cell or a neuron are “huge creatures” relative to that scale, so quantum phenomena in them disappear through decoherence. It explains through the law of large numbers how an enormous collection of components turns microscopic probabilistic behavior into macroscopic classical behavior, illustrating this with rolling a die many times and with the parable of blue and yellow particles that together produce a “green” liquid. It notes that there is a field called quantum biology and that there are attempts to connect quantum phenomena to DNA and to randomness in mutations in evolution, but states that even if there are quantum phenomena there, they provide randomness and not choice. It adds a reservation about the state of his own knowledge on the subject and allows that quantum theory may perhaps “weaken” arguments against free choice without explaining it, with a commitment to return to that later.
Consciousness, collapse of the wave function, and myths
The text presents as a “myth” the claim that human consciousness causes collapse of the wave function, although it attributes such suggestions to Wigner, von Neumann, and Penrose. It describes an experiment in which a detector sends information to a computer that destroys itself, so that no human ever saw the information, and yet the result still became particle-like. From this it concludes that there is no indication that human consciousness is a unique factor in collapse.
Philosophical conclusion and continuation of the series
The text concludes that chaos does not solve the problem of free choice, and quantum theory does not provide a mechanism of choice but only randomness, and is also irrelevant to neurological scales. Therefore, if one accepts physicalism, free choice cannot exist. It presents a dilemma: either deterministic physicalism without free choice, or dualism that may perhaps allow free choice, and declares that in the next lecture he will begin moving into neuroscience in order to examine the issue. It ends with a clarification about the direction of body-mind causality: a non-physical will that affects particles violates laws of physics such as Newton’s second law, whereas the effect of a physical event on an experience such as pain does not contradict any physical law because physics “says nothing about non-physical things” and does not determine what causes pains.
Full Transcript
[Rabbi Michael Abraham] Okay, first of all, good morning. I want to begin with a short summary of where we are in the overall progression, so we can get into the context. Right now I’m talking about the question of how far one can fit the libertarian conception—that yes, there is free will—into the picture given by physics. And the motivation for having this discussion is because of the not-entirely-unambiguous connection between the question of materialism and the question of libertarianism or determinism, right? The question of whether there is free will or not, and the question of whether the world contains only matter or whether it also contains other dimensions. I said that on the face of it, these two questions are independent. You can be a libertarian and still believe that the world contains only matter—so within matter there are degrees of freedom that allow free choice. And you can be a dualist determinist, meaning you believe that the world contains both matter and spirit, but both operate in a completely deterministic way. Therefore, conceptually, there is no necessary connection between the question of materialism—whether the world contains only matter—and the question whether we have free choice or not. Okay, so how do I want to crack this question of the connection? Because in the end people do connect determinism with materialism. It is commonly thought that someone who is a materialist, someone whose world contains only matter, is also a determinist. He does not believe in free choice. And someone who believes in free choice is a dualist, meaning he usually thinks that besides matter there is also spirit in the world. And the question is why. Because on the conceptual level, you could completely separate the two questions. So then I said that this really is rooted in the laws of physics. It’s not conceptual, it’s simply factual. We check the laws of physics, and what we discover shows us that there indeed ought to be a connection between the two questions. How does that work? In order to show a lack of connection between the two questions, what I basically need to do is show that there is room within physics. Meaning, someone who wants to be, say, a materialist—to believe that the entire world is only matter and physics—and nevertheless believe in free choice, meaning to separate the two questions, has to show how free choice is possible in terms of the laws of physics. Okay? If we rule out the possibilities of fitting these things into physics, then we are back to saying that if you are a physicalist, if you think there is only matter in the world, you cannot believe in free choice. Here we found why these two questions are connected to one another. So in the course of this search, I began discussing it—I said there are three possibilities for where to look, two and then later we’ll see a third: chaos, quantum theory, and emergentism. Those are basically the three kinds of proposals that come up in the literature for inserting free choice into physics. So last time we examined the subject of chaos. And we saw there that the connection people make between chaos and free choice stems from conceptual confusion. That confusion basically hangs the inability to predict what will happen together with the claim that we have free choice. And that connection exists only in one direction, not the other. Meaning, if we have free choice, then it is impossible to predict in advance what we will do. That is certainly true. But if it is impossible to predict in advance what we will do, that does not necessarily mean we have free choice. It may be that we do not have free choice, but it is impossible to predict what will happen or what we will do because it is terribly complicated. Right, the calculation is extremely complicated. There is such a calculation, meaning the world is deterministic, but the calculation is very complicated and therefore it cannot be done. Last time we saw that the inability to predict in the class of problems called chaos is because of complexity, not because of freedom in the system. I brought examples of this, right, I’ll share here the drawing we saw last time. Here, this was the drawing. I said that we put a little ball at the top of a mountain, and the question is whether we can predict to which side it will fall. Now assuming there is nothing around, and the mountain is completely symmetric, and the little ball is a point, and so on—actually even if it’s not a point—it will stay standing in the middle. It won’t tilt to either side. But in reality itself you can’t reduce things that far, and whenever we place it, we will place it a tiny bit leaning right or a tiny bit leaning left, or a slight wind will come and move it right or left. And because of that, it will always fall to one side, but we have no way of predicting in advance which of the two sides it will be, because it depends on complicated things like wind. Climate is a very complicated thing; climate is a chaotic phenomenon, or many chaotic phenomena. Or just placing the ball on the mountain top—the question whether I placed it a little to the right or a little to the left, I have no way of knowing exactly, and it could happen to be a millimeter to the right or a millimeter to the left, and that is what will determine it. Therefore I have no way of predicting in advance where the ball will fall. Does that mean that this ball has some kind of freedom? Meaning, that the circumstances do not dictate what happens to it? The answer is of course no. The ball is dictated; the circumstances completely dictate what will happen with the ball. So why can’t I predict in advance what will happen? Because I do not have all the information, or because the calculation is very, very complicated—one of those two. Either I do not have all the information—that is the case where I don’t know where exactly I placed it, whether I placed it a little to the right or a little to the left; that is lack of information. Or it could be that my information is complete, I placed it exactly in the middle, but the calculation required to know what wind will come is extremely complicated, because meteorology is a very complicated field. And therefore one of these two problems prevents us from predicting in advance what will happen to the ball. But that does not mean there is some sort of departure from physics here, some kind of free choice. There is nothing free here; there is only inability to predict, that’s all. I talked about a piece of paper that I throw from the third floor and it falls down, and of course I can’t know where it will land, because every little gust of wind will carry it in different directions, and I have no way of knowing in advance where it will land. Same thing as here. Again, is there something here beyond physics that influences this piece of paper? Absolutely not. It’s all physics. The physics is complicated, and because the physics is complicated I don’t know how to predict in advance what will happen. But the fact that I don’t know how to predict in advance does not mean there is freedom here. If there were freedom, I couldn’t predict in advance—but the fact that I can’t predict in advance does not necessarily mean there is freedom here. Therefore that is the mistake of people who tie free choice to chaos. Chaos has nothing whatsoever to do with the problem of free choice. Chaos is simply inability to predict because the problem is complicated, not because there is some freedom in it such that no calculation can produce the result. There is such a calculation; it’s just hard for me to do it. That is basically the reason I cannot predict. At the end of the previous lecture I made a distinction between two kinds of doubts, or two kinds of vagueness, if you like. I called them ontic vagueness and epistemic vagueness. Epistemology is the theory of knowledge, and ontology is the theory of being, the study of reality itself.
[Speaker B] A question, yes, if I may. Rabbi, we can’t hear you.
[Speaker C] Nor see you.
[Rabbi Michael Abraham] Yes, my internet disconnected, I’m sorry. There have just been some internet problems since last night, and I hope it will continue okay. In any case, at the end of the previous lecture I distinguished between epistemic doubt and ontic doubt. Epistemic doubt is doubt that arises from absence of information. I’m missing some of the information about reality, and therefore I’m in doubt. I don’t know whether a son was born to me or a daughter was born to me, so I’m in doubt, but what was born is either a son or a daughter. Reality itself has one clear answer. There is no vagueness in reality itself. There is doubt created as a result of absence, or partial absence, of information. That is what I call epistemic doubt, a doubt of knowledge. The problem is that I do not manage to know reality. By contrast, in ontic doubt, this is doubt that exists, that is created because of vagueness in reality itself, not in my ability to know it. I am missing no information. Reality itself is not fully determined—not that I don’t know everything. I gave an example of this: betrothal that is not fit for intercourse. I sent an agent to betroth a woman for me. He betrothed her—he went to a certain man, gave him a perutah, and betrothed one of his two daughters. Okay? Now the man died, the agent, and the father also died. No one knows which of the two daughters is betrothed to me. That is epistemic doubt. Why? Because the one who was betrothed is one specific daughter; the Holy One, blessed be He, knows which daughter is betrothed to me, it’s just that no one in the world knows. So I’m in doubt because I’m missing information. But that information exists. There is an answer, I just don’t know it. That is epistemic doubt. But what happens if the agent comes to the father and says to him: one of your two daughters, and I don’t care which one is betrothed to me with this perutah? Meaning, from the outset he does not define at all which of the two daughters he is betrothing. Fine? Now he doesn’t even need to die, and the father also doesn’t need to die. Now we are all in doubt, but this doubt does not stem from lack of information, as Rabbi Shimon Shkop explains. This doubt does not stem from lack of information. Even the Holy One, blessed be He, does not know which of the two is betrothed to me, because there is no specific one of the two that is betrothed. He betrothed one, but did not define who. Once he did not define who, then there is no one who is betrothed. Meaning, the problem is not only that I don’t know who the betrothed one is; the problem is simply that there isn’t one—there is no one who is betrothed. That is what I call ontic doubt, not epistemic doubt. And maybe you could call it, as opposed to doubt, let’s call it vagueness. Vagueness is because… it’s fuzziness, right, it’s fuzzy logic, logic that deals with vague situations, where the answer is not simply yes or no, but some kind of in-between answers. Okay? So vagueness deals with lack of determination in reality itself. Doubt… in the case of doubt, reality itself is clear, I just don’t know. Right? All the doubts in Jewish law that you can think of are doubts of the second type, the epistemic type. If I found a piece of meat in the marketplace and I don’t know whether it is kosher or non-kosher, and there are stores—right, the whole well-known story—the piece itself is either kosher or non-kosher, that is clear. All that is lacking is my information. Meaning, I don’t know its status, but it has a clear status; the Holy One, blessed be He, knows. Okay? Or a woman—whether she is fit or unfit, disqualified or not disqualified, permitted to a kohen or forbidden to a kohen. Again, the problem is only a problem of information. In reality itself the answer is clear. I do not know. All doubts in Jewish law are epistemic doubts. Ontic doubt means pathological cases like betrothal not fit for intercourse; there are a few more cases like that, but these are really esoteric cases. Very few cases in Jewish law are ontic doubts. Okay?
[Speaker C] So what about twilight?
[Rabbi Michael Abraham] So they asked me about twilight last time. Simply speaking, twilight too is an epistemic doubt, not an ontic one. Day passes at some stage and becomes night; I just don’t know at which moment that happens. That is the straightforward conception of twilight. I said that the lomdim there, right, the analytical scholars there, introduce all sorts of additional possibilities, and maybe it also depends on a dispute among the tannaim, but that is the straightforward conception of twilight.
[Speaker B] That actually reminds me… it reminds me of the example you often give about that drawing that turns from a fish into a bird or something, where I understood from you precisely that there is no point at which it becomes a fish into a bird.
[Rabbi Michael Abraham] נכון, but there the problem is only one of definition. I don’t think the problem is in reality; the problem is in the definition: what do you define as a fish and what do you define as a bird. By the way, also with twilight, the conceptions that see twilight as an ontic doubt and not an epistemic one are also of that type. It’s not really doubt in reality; reality itself is completely clear. Everything that happens, the Holy One, blessed be He, knows exactly what happens. How much light there is at every moment, the Holy One, blessed be He, knows. The question is a definitional one: how much light has to be present for us already to call such a state “night.” But that is not a question about reality; it is a question of definition: how do I define the concept of night. Therefore here you might perhaps call it ontic doubt, doubt in reality, but it isn’t really. In reality itself there is no doubt whatsoever. At every moment there is a given amount of light and the Holy One, blessed be He, knows it completely. At most I do not know it—that is epistemic doubt. Why then is there perhaps a doubt that looks like ontic doubt? Because I don’t know how to define the concept “night.” How much darkness or how much light has to be present so that it is no longer called day but called night. But that is a question of defining a concept. That is vagueness, like the heap paradox or things like that.
[Speaker C] And what about an androgynos?
[Rabbi Michael Abraham] An androgynos too is, in my opinion, a question of definition. With a tumtum—yes, with a tumtum too it’s an epistemic question. Because inside there is something, I just don’t know what is there. And an androgynos has both signs, but there is no doubt here. In reality itself everything is clear. There is nothing that is either this or that in reality. The question is one of definition: how do I define such a creature? Do I define it as a man, as a woman, or as both. And again, it’s a question of definition. It’s very hard… to think of doubts that are really ontic doubts, actual vagueness.
[Speaker D] What? He has until a quarter to five.
[Rabbi Michael Abraham] Cases that are not fit for intercourse are an excellent example of this. There are others. For example, someone has five coins in his pocket and says, one of them is consecrated property. He consecrates one of them. But he doesn’t care which one. So it’s like betrothal not fit for intercourse: there is one coin that is consecrated, but it is not a defined one. It’s not that I don’t know which consecrated coin it is. There is no one specific coin that is consecrated. I consecrated one, but I didn’t define which. And so on.
[Speaker E] Sometimes there’s retroactive clarification, where even though at first I don’t define and I don’t know, retroactive clarification tells me what it was determined to be.
[Rabbi Michael Abraham] In the topic of retroactive clarification there is a dispute among the medieval authorities (Rishonim), the view of Rashi, that in the topic of retroactive clarification, according to the one who says there is no retroactive clarification, the initial state is epistemic doubt. Meaning, when I say, for example, in the case of one who buys wine from the Cutheans, right? I have a barrel of wine and I say: two log out of it—I want to separate one-fiftieth, average-quality wine for terumah—so I say, two log out of the hundred that will remain on Saturday night shall be terumah. Now the question is whether I’m allowed to drink now. This is the topic of retroactive clarification. And Rashi’s claim is that even according to the one who says there is no retroactive clarification, the reason I’m forbidden at the moment to drink the wine is because perhaps I’m drinking terumah. Meaning, Rashi understood that within the system there are two log of terumah, I just don’t know which two log are the terumah and which are not. There are others who hold that there is no terumah in the system at all, because one cannot separate terumah in such a way. Now according to Rashi’s view, that there are two log, here we need to discuss: does he mean epistemic doubt, that there are two defined log and I just don’t know which, or that they are mixed because liquid is mixed with liquid, so with liquid mixed into liquid everything is mixed into everything and I cannot be careful to drink the log that are not terumah—or does he really mean it as ontic doubt, and he is basically claiming that every two log have some aspect of terumah in them. Every two log. Like one who betroths one of two women, or consecrates one of several coins he has in his pocket, and so on. So here too, I basically separated—I applied the designation of terumah to one pair of two log out of the hundred log here. But since I did not define which two log, because I defined it only for the future, and a future definition does not take effect in the present according to the one who says there is no retroactive clarification, then this is basically a situation as if I separated two log but did not determine which two log. Exactly like betrothing one of two women. That is probably the more plausible way to understand Rashi’s view. Okay? So yes, that too can be a state of lack of determination in reality itself. Meaning, ontic doubt is what I called vagueness, fuzziness. Now I return to our line of argument. So basically we are now in a situation where chaos is epistemic doubt. By contrast, free choice is supposed to be vagueness. Not doubt. There has to be something in reality itself that is free. It can go this way and it can go that way—not that I just don’t know what will happen. That’s what happens in chaos. Rather, in reality itself it can happen this way and it can happen that way. You understand, after all, what is free choice? Free choice means—and I talked about this, I’m only reminding you—free choice means that right now there are given circumstances. And let’s say I know all the information about the circumstances, everything, and I also know all the laws of nature, and I have infinite computational power. All the problems of chaos are gone. Still, the libertarian basically says that a human being can freely choose whether to do X or not do X. Meaning, the circumstances do not dictate what will happen in the next moment. What will happen in the next moment can be more than one possibility, even though the circumstances are fully defined, fixed, and known. That is the meaning of free choice. What does that mean? It means that the freedom here is not epistemic freedom. That is, it’s not that I’m missing some information about the physics, but that the physics simply does not determine it. Even if I knew all the physics, free choice would still remain. That is basically the claim. Or in other words, in order to insert free choice into physics I need to find ontic room in physics, not epistemic room. After all, chaos was epistemic room and not ontic room. So now the question is whether there is ontic room in physics. The only candidate for this is quantum theory. Therefore it is natural to discuss quantum theory here in this context. I want to do that briefly. And again I’m sharing the diagrams. So look, as Richard Feynman said, the best way to present quantum theory is through the two-slit experiment, the double-slit experiment, okay? So I— the history of the double-slit experiment is pretty old, beginning I think in the seventeenth or eighteenth century, Young’s experiment, eighteenth, Young’s experiment, and the background to it is a dispute between Huygens and Newton, Huygens-Fresnel and Newton, over the question of what light is. Newton argued that light is made up of tiny particles of light, and Huygens argued that light is a wave. Meaning, it is a spread-out entity. Think, for example, of a wave in the sea, right, waves we know in water. If we put a piece of wood on the water, even though there are waves, the wood rises and falls; the wood does not really move with the wave. Why? Because in the wave, what moves forward is not the water. The water does not move forward with the wave in principle—of course it moves a little because of the conditions—but the water does not move forward in the wave. What moves forward in the wave is some kind of force field or energy that passes through the water, but the water itself does not move forward. So you can’t say that the wave is made of water molecules or atoms—yes, molecules, water molecules. You can’t say it is made of that, because the wave is not the water at all. The water is the medium through which the wave passes. So what is the wave? The wave is some sort of entity—energy, a field, or a force field, or something like that—which is a global entity; it is not located at one particular point. The whole phenomenon is what is called a wave. A wave is not a collection of small things that together create a wave. That would be if I saw the water as the wave, but the water is a collection of little things that together are water. But when I talk about the wave, I am talking about a phenomenon whose essence is global, not local. Meaning, it is not a phenomenon located at one point in space, but one that is spread over a large region of space. It is not made up of a collection of many little things. Okay? That is basically the definition of a wave. Now the dispute between Huygens and Newton was about light: what is light? Newton argued that light is a collection of tiny particles, and Huygens argued that light is a wave. So Young suggested doing an experiment to check who was right. That experiment is based on a phenomenon, phenomena characteristic of waves, called interference. What is interference? When two—say, I send two waves from two different sources—if they meet in the same region, then there is some interaction between them; they add up in some way. Let’s say that the wave is drawn in the shape of a sine curve. Just look for a moment at this picture—do you see this picture? There is a wave here that goes up and down, let’s say something like this, and there is another wave whose peak would be around this area, so the sum of the two waves would look like basically some kind of plateau, there would be a high peak here and here. Okay? By contrast, if the second wave has an anti-peak here, then it will cancel out this peak and reach zero. That is called constructive interference or destructive interference. Okay? That is a phenomenon of waves. In particle phenomena, of course, that does not happen; each particle stands on its own. Now he says, let’s see. In Young’s experiment, basically what he did was send beams of light and pass them through a screen—this is the screen—and in this screen here there is a slit. Okay? Here there is a slit, and this is the light source. The light source sends out a beam of light—this is the dotted line—here there is a slit, and it goes through to a celluloid screen, to a screen that photographs, that records the image, the impact of the light, okay? A photographic screen. Now obviously if I send light through this slit, then the light will arrive at the region on the photographic film opposite the slit. Right? Because the light—all the other directions, all these rays, those that go like this and those that go like this and those that go like this—all of them will get blocked. The only one that will pass, the only light that will pass, is just the light that comes directly to the slit and continues here. Therefore the image we will see on the photographic film is the graph. When I check the amount of light that arrives on the photographic film, we will see that here there is a peak in the amount of light, there are slight deviations to here, and here no light arrives, and here no light arrives either. Okay? So that is if we send a collection of particles. This is a source of particles, and in all directions—notice all these arrows—it sends particles in all directions at random. Now there are two slits, there is a slit here and a slit here. So of course all the particles that hit the screen here will not pass through. The particles that do pass through are those that arrive at this slit and those that arrive at this slit. Those that arrive at this slit continue onward and create a peak here. Those that arrive at this slit create a peak here. And what we get is an image of two peaks. Okay? The particles basically arrive more or less in the region opposite the slit. There will be some particles that arrive a bit here, there will be some particles that arrive there, but overall there will be some peak that slopes down. And opposite the second slit there will again be a peak that slopes down.
[Speaker G] This is a picture of the two-
[Speaker H] slit experiment.
[Rabbi Michael Abraham] Okay, for some reason I always come back on mute. In any case, the picture of two slits when I send particles is a picture of two peaks. What happens when I send a wave? Right, what did Young get when he did an experiment with two slits, not with one slit? He got this picture. Now notice, this picture is a wave beam. I send light, like from a flashlight, and the light goes in all directions, and here there are two slits. Notice, he got the two peaks that would also be obtained from particles, but in the middle there is another big peak, which is the interference of the two rays arriving from here and from here. Okay? These two rays go on, some goes here and some goes here, and they interfere constructively, as it's called. And therefore this is the wave picture. When Young got this result, it was seen as a decision in favor of Huygens. Newton was a great genius, but in optics he lost, meaning he was wrong. He thought it was particles, and Young's experiment showed that it was waves. Okay? By the way, that's not the end of the story. But that's what happened in Young's experiment.
Well, a hundred years later, a similar debate developed in the wake of quantum theory regarding particles. They did Young's experiment with particles, again a two-slit experiment. Right? So again, in the one-slit experiment, the single-slit experiment we saw here, whether it's particles or waves, the result is the same result. Therefore a one-slit experiment cannot decide whether we are dealing with particles or waves. But a two-slit experiment can decide. In a two-slit experiment, notice, this is the particle result, a peak here and a peak here. And this is the wave result: a peak here, a peak here, but also a high peak in the middle. Okay? And therefore the two-slit experiment, because there is interference of the rays coming from this slit and this slit, there is a ray that goes like this and a ray that goes like this, and they interfere constructively, because it is the same distance between the two slits; when they travel the same distance the interference is constructive, so therefore a peak is created in the middle. That's with waves. With particles there will be only these two peaks, there won't be a peak in the middle.
So once again a debate arose in quantum theory about the nature of particles, of electrons. They decided to do a two-slit experiment with electrons. They did the experiment, and to their amazement they discovered a picture like this. That is, it turned out that electrons too are waves. Basically there are interferences of electrons. But here people said that maybe, although I think in principle that's not correct, maybe it's simply because there are many electrons in the beam and they spread out along this photographic film, and therefore it looks like a wave. What will happen if we do an experiment with a single electron? Or a very, very sparse beam that sends one electron at a time, pauses, then another electron—not a stream of many electrons. In such a case people had no doubt that the picture obtained would be this one, since a single electron is certainly a particle; it's not many, so they don't spread out over space. One electron, if I send a single electron. And then another single electron and another single electron at a slow rate. The expected picture is this one. Some of the electrons will pass through this slit, there will be a peak here; some of the electrons will pass through this slit, there will be a peak here; there will be no middle peak here. To their amazement they discovered that the picture obtained is this one. Even in the case of electrons, a sparse electron beam, there is a peak in the middle.
Or, in other words, let's make it even more extreme. Suppose I do an experiment with a single particle, one electron. I send one electron toward this screen, and in this screen there are two slits. The picture obtained is this picture, from a single electron. That basically means that a single electron is a wave and not a particle. And this is the beginning of the whole scandal of quantum theory, where particles are seen as waves and waves as particles. The accepted interpretation of this experimental result was that in fact this wave that we measure here is a wave that describes probabilities, the probabilities of an electron passing through this slit or through this slit. But notice, this is probability in the ontic sense and not in the epistemic sense, and that is why quantum theory is so important for this discussion. Why? Because if it were a probability in the sense that either the particle passes here or it passes here, then what would happen with a single particle? We would get either this peak or this peak; we cannot get this whole picture from a single particle. If with a single particle we get this whole picture, that means that the particle itself partially passed through here and partially through here, and part of it interfered here toward the middle in constructive interference.
Or in other words, the wave we are talking about in the context of an electron is a wave of quantum probabilities. And quantum probabilities basically mean—think of the electron itself as a wave. That's not exactly right, because it doesn't work exactly like light; it's a wave of probabilities, not a wave of the particle itself, but it is not a particle in the epistemic sense. It's not that I don't know whether the particle passed through this slit or this slit. The particle passes through both slits. I remind you again of betrothal not handed over for intercourse; it's exactly the same thing, completely quantum logic. When I betroth one of two women, it's not that there is a fifty percent chance that this one is betrothed to me and a fifty percent chance that that one is betrothed to me. That's true in a situation of epistemic doubt, where one of them is really betrothed to me and I don't know who, so I say there's a fifty percent chance it's Rachel and a fifty percent chance it's Leah. But in the case of betrothal not handed over for intercourse, then here Rachel is betrothed to me with fifty percent intensity and Leah is betrothed to me with fifty percent intensity. It's not that there is a fifty percent question whether Rachel is betrothed to me or a fifty percent question whether Leah is betrothed to me. That would mean that only one of the two is betrothed to me and I don't know which. But in ontic doubt, it means that each of the two is fifty percent betrothed to me, and therefore I need a bill of divorce from both of them. We talked about doubt according to Maimonides, that Torah-level doubt is ruled leniently, so why can't I have relations with one of them—after all, I only have a doubt? The answer is no, it's certain: she is certainly betrothed to me by fifty percent.
The same thing in quantum theory. In quantum theory, its novelty over chaos or over other statistical phenomena is that here the statistics are ontic and not epistemic. That is, the particle itself passes—fifty percent of it passes through one slit, fifty percent of it passes through the other slit, and some of it interferes in between and creates this middle peak. And therefore quantum theory is perceived as a possible basis for discussing ontic gaps. That is, within the physical world itself it turns out that there are possibilities that are both possible in reality itself, not merely that I don't know. In that sense this is not like chaos, which is only epistemic, because here the vagueness is fuzziness, not doubt; it's vagueness. In reality itself there are two possibilities. And this is really fertile ground for believers in free will. Because it basically means that even if the given reality exists—here, I sent one particle from here, everything is given. I sent one particle from here, there are two slits, everything is given. Now tell me what physics says. Physics says that it can. It can pass through here, and it can also pass through here. So that means exactly free choice.
Now I'll say more than that. Suppose I place a detector next to this slit. A detector, right, is something that measures the passage of the particle. If the particle passes through this slit, the detector will beep. If the particle passes through this slit and the detector is here, then the detector won't beep. Okay? Now I put a detector next to this slit, where my cursor is. The picture obtained, to the physicists' amazement, is this picture. The interference disappeared; a particle picture is obtained. When the detector beeps, then the particle passed through this slit. When the detector doesn't beep, then the particle passed through this slit. But in any case it passes through only one slit, therefore there is one peak here and a second peak here. There is no middle peak; the peak that was here does not exist. And this is what is called the measurement problem, or: when we measure where the particle passes, it goes back to behaving nicely. It stops being a wave and goes back to being a particle. It doesn't like being watched when it's a wave. If you check it, it behaves like a particle, yes, like a student in class—when the teacher is looking, he behaves nicely. When the teacher isn't looking, he does all sorts of tricks. Okay? It's exactly the same with this particle. If we do not look through which slit it passed, it passes through both of them and also interferes with itself. If we do look through which slit it passed, we put up a detector, then it passes either through this slit or through this slit, but I get two peaks. There is no interference.
Now understand, there is a very interesting point here, because the fact that I put a detector here does not say through which slit it will pass. It can pass either here or here, but it can pass through only one of them, not both together. If there is no detector, it can pass either here or here or through both together, and then there is interference. If there is a detector, then it can pass either here or here, but there is no interference. But it's not that if there is a detector we return to classical behavior. In classical behavior the particle passes through the slit toward which you sent it. Okay? In the quantum view, no. Even if I measure it and it goes back to behaving like a particle, there is still quantum uncertainty. The uncertainty says the question is whether the particle will pass through here or the particle will pass through here. The fact that it is a particle only means that it does not pass through both places together. It passes through one of them. But quantum theory still remains; we have not returned to classical physics. Rabbi. Yes.
[Speaker G] What is the definition of a particle in this context?
[Rabbi Michael Abraham] What do you mean? A little point-like ball running around, the way you intuitively understand it.
[Speaker G] So if it's a little ball, like the smallest thing there can be, then how does it pass through two places?
[Rabbi Michael Abraham] So I'm saying, if it's a little ball, then it doesn't pass through two places, it—
[Speaker G] passes through one of them. So why is there interference? You just said—no, there is no interference.
[Rabbi Michael Abraham] If it's a little ball, then there is no interference. If you measure it, it's a little ball; if you don't measure it, it's a wave. So if it's a little ball, then it will pass either here or here. It can also pass through here.
[Speaker G] The measurement affects whether it's a little ball or a wave? How can that be?
[Rabbi Michael Abraham] That's quantum theory. Don't get me tangled up in this issue. I don't think anyone knows how to explain it, but that's what quantum theory says. Feynman once said—you know, there are myths among physicists—that Arthur Eddington, they once told him, because he was a British physicist, perhaps one of the first very well-known astronomers, a Nobel Prize winner, and they once told him that there are only three people in the world who understand relativity theory. So he asked, who is the third? It's obvious that it's Einstein and him; the only question is who the third is. But Feynman, following him, said that's not true at all: relativity theory is very easy to understand; there are many people who understand it. Quantum theory nobody understands. Including those who built it. Quantum theory cannot be understood. But those are the facts. Yes, in the book I brought some motto from a Japanese physicist who wrote a book—Michio Kaku—he wrote a book called Hyperspace, and there he says that quantum theory is the most absurd and stupid theory in the world. Its only drawback is that it is completely true. Meaning, it's very irritating, very incomprehensible, but time after time we get slapped in the face with confirmations that it works. Okay, so you can't fight this with 'God does not play dice,' but it didn't help him. Meaning, he lost that battle. Okay, but before I continue.
[Speaker G] So what does quantum theory actually say?
[Rabbi Michael Abraham] What? Again?
[Speaker G] What does quantum theory say?
[Rabbi Michael Abraham] In brief, what I've said until now. Quantum theory basically says that a particle, as long as you haven't looked at it, is basically a wave. And therefore it can pass through both slits and also interfere with itself. If you look at it, that's already measurement theory in quantum theory. I'll say again, there are different reconciliations here, different interpretations; I'm using the Copenhagen interpretation, the accepted interpretation, without getting too tangled up. So if you look at the particle, then it goes back to being a little ball, but you still cannot know through which of the two slits it will pass. It will pass through only one, not two. There will be no interference, but through one of the two, and therefore the picture will still be a picture of this and this, two peaks.
In any case, the point is, just to complete the amusing historical description, that Newton doesn't give up so quickly; he too was no small genius. You remember that he lost the argument over what light is. It turned out that light is a wave. Quantum theory turned the wheel back. A wheel, yes—it turned the wave back into a wave. So it turned the wheel back, and suddenly told us that if we do Young's experiment—and they did—if you do Young's experiment with a very sparse beam of light, light at a very, very low intensity, meaning single photons. I'm already using the language of quantum theory. You get this picture, the two-slit experiment. It's particle-like. And then quantum theory basically says that not only is the electron also a wave and not only a particle, but light too is not only a wave but also made up of particles that today are called photons. Okay? And absurdly enough, Einstein was actually the first to discover them, or to discover the indication of their existence, even though he was one of the fiercest opponents of quantum theory. Meaning, he himself created it and then fought against it all his life.
[Speaker C] Just to complicate things, there's Schrödinger's cat.
[Rabbi Michael Abraham] Yes, I'll get to that in just a moment. Okay. So quantum theory isn't hard to complicate. But I דווקא want to present only the basic scheme so that we understand why, in my view, this is unrelated to the question of free will. Okay? So now, the interpretation—as I started to say earlier—the accepted interpretation of quantum theory is basically that every—now I'm no longer distinguishing between wave and particle, because every entity in the world, both an electron and light, can be both wave and particle. So you can't speak about waves and particles as distinct entities, but rather as different states of physics. There is a particle state and a wave state.
Now wave-wise, say in the wave state, we're talking about some particular function that receives a specific value only if I measure it. For example, if you recall the two-slit experiment, then as long as the electron is a wave it is basically present throughout space, it passes through both slits, it interferes with itself, it is basically a wave. Okay. If the electron—if I measure it—the electron is a particle; the measurement puts it into a particle state, and now it has a location at a certain point in space. The electron, when I measure its location, suddenly turns into a particle that has a well-defined location at a certain point in space. This is what is called the collapse of the wave function. And the accepted description of this matter is the following. Basically, what does wave mean? Wave means exactly—as in betrothal not handed over for intercourse. If I were teaching quantum theory at the university, I would begin with a Jewish law introduction. I think that's the best explanation of quantum theory. Because there too you can understand it intuitively. In quantum theory they immediately start with something you can't grasp intuitively, whereas in the legal world there is no problem understanding this. The quantum state is a natural and compelling state in that situation.
So what happens there is the following. There is a state of superposition, as it's called. Superposition means that when I relate to the particle as a wave, this means a sum of particle states. That is, when I say that the particle is a wave, I am basically saying: this particle is the sum of a particle passing through slit A plus a particle passing through slit B plus a particle passing through both—a sum of many, many states. Okay, and this sum together is called the wave function. And that is what is called superposition. And when I ask myself through which slit the particle passed, the answer is: the particle passed both through slit A and through slit B, even though it is supposedly a particle. Because it isn't—it is a superposition of several particle states.
And here I come to the example Eli raised earlier of Schrödinger's cat, yes, the experiment that tries to reduce this view to absurdity. It's a hypothetical experiment, of course. You put a cat inside a closed box, and inside this box there is a vial of poison, poisonous gas, such that the moment the vial opens, the poison disperses in the box and the cat dies. Okay, now the opening of the vial I leave to a switch that determines whether the vial opens or does not open, and it is a quantum switch. That is, either it opens or it doesn't open—it's a superposition of two states. Fine? Now the question before I measured what happened is: what is the condition of the cat? Like children's puzzles—where is the cat hiding in this picture, right? So it turns out that according to the accepted interpretation of quantum theory, the cat is both alive and dead. It is in a superposition of a state of a live cat and a state of a dead cat. The sum of these two states is the cat's condition until the measurement. When I open the box, I will discover either a live cat or a dead cat there. Why? Because opening the box is a measurement. I look: is the cat alive or dead? The moment I looked, it went back to being a rational cat. Now it is already either a live cat or a dead cat. By the way, I can't know which. Either alive or dead—I can't know which—but it will be either alive or dead; it will not be both together. As long as I haven't opened the box, it will be both together.
Now what this basically means is that ostensibly an opening has appeared for hanging free will on quantum theory. Quantum theory allows me to insert free will into physics. Why? Because I can now say that a person is in a given situation, but that situation is a superposition. Now the moment he chooses, this superposition collapses; it becomes a well-defined state, but he can choose either state A or state B. The superposition allows him both states. By the way, there is a certain probability for each state. For example, if we go back to the electron passing through the two slits, then even in the electron case I can tell you what the probability is that it will pass through slit A and what the probability is that it will pass through B. I cannot tell you through which slit it will pass. But I can tell you what the probability is that it will pass through each of the slits. That yes, even in the particle state. Meaning, the wave function basically describes what the probability is for each measurement result I perform. If I measure whether the particle passes through slit A, then knowledge of the wave function will tell me the probability of getting that it passed there and the probability of getting that it did not pass there.
Okay, so coming back to us: basically, the interpretation of quantum theory for free will says that quantum theory lets me insert free will into physics. Why? Because one can say that the person is in a state of superposition, and choice is some kind of collapse of the wave function into a given state. For example, I have to choose whether to give charity or not give charity, so my brain is in superposition. Okay, now since it is in superposition between a state of giving charity and not giving charity, like the live cat and the dead cat. Okay, and King Solomon, of course, knows—I have another solution for him to the problem of the two women with the live child and the dead child. Okay? Let him give both of them a superposition of a live child and a dead child. In any case, for our purposes, the person is in a superposition of Mickey giving charity and Mickey not giving charity. He is in a superposition. Now the moment we measure, or I decide, or if you like others look, then it collapses into one of the two states: either I give charity or I don't give charity. And there you have a situation in which the current circumstances do not dictate the next result deterministically. There can be two results, and both are acceptable according to the laws of physics even though the given state now is completely known. So ostensibly quantum theory allows free will within physics—that is the claim.
[Speaker G] Rabbi, how does superposition allow a thing and its opposite?
[Rabbi Michael Abraham] It's not a thing and its opposite, it's either A or B.
[Speaker G] But A contradicts B.
[Rabbi Michael Abraham] It doesn't contradict B. A is different from B. And passing through slit A and passing through slit B is contradictory only if you assume that this is a particle that can pass through one slit. But if it's a wave, then it can pass through both. And when it passed, it passed either through A or through B; it didn't pass through both. You don't get to a contradiction. It's otherness, not contradiction.
[Speaker G] And dead and alive? I didn't understand. In dead and alive.
[Rabbi Michael Abraham] Why is dead and alive not a contradiction? It is in a superposition of a state of a dead cat with a state of a live cat. That's not a contradiction. It is in the sum of two states. Now when you measure it, it will be either dead or alive, it won't be both. But even before that it wasn't both, understand. To say that it is in superposition does not mean that it is both dead and alive. Rather, that the state it is in is a compound state, fifty percent of which is a state of death and fifty percent of which is a state of life. Metaphorically, it is rattling—half dead, half alive. Of course that's not true, but only to illustrate. It's a mathematical hybrid of two states. It is not to say that it is both alive and dead. It's like when I betroth one of two women, Rachel and Leah. Right? If Rachel is my wife, then Leah is not my wife. If Leah is my wife, then Rachel is not my wife. Correct? Because I betrothed only one. So what is the superposition state we described? It is a sum of states. Either Rachel is betrothed to me and Leah is not, or Leah is betrothed to me and Rachel is not. The real state is the sum of these two states. But it's not correct to say that both Leah is betrothed to me and Rachel is betrothed to me, because only one is betrothed to me. In each of the two states only one is betrothed to me. Which one is that one? It could be either of them.
Like, you know the story about oneg Shabbat, that the Or Sameach once said about the Rogatchover—they were both rabbis in Dvinsk, in Danzig, right? So the Rogatchover was the rabbi of the Hasidim and the Or Sameach was the rabbi of the Lithuanians, the Mitnagdim. So the Or Sameach once said about the Rogatchover that when he rides the train for an hour, he finishes half of the Talmud. So they asked him: which half? So he said: whichever one you want. Meaning, he finishes both halves. That's a state of superposition.
Anyway, for our purposes, this claim that says I can insert free will into physics through quantum theory ostensibly keeps alive the possibility of being a materialist on the one hand, believing that the whole world is matter and physics and that's all, and on the other hand being a libertarian, believing in free will. That is the importance of the discussion of quantum theory. Now I want to explain why I disagree, why I think that with quantum theory this doesn't work. First of all, I want to claim that even if all this were true, this still would not be free will but a lottery. When I place a detector next to one of the slits, the detector does not determine through which slit the particle will pass. It only moves the particle from a wave state to a particle state. But through which of the two slits will it pass? That is a lottery whose probabilities are determined by the wave function. That is, the detector does not determine through which slit the particle will pass.
Now free will—and I prefaced this, remember van Inwagen? I said it's all a matter of a dilemma, that there cannot be free will because it's either determinism or indeterminism, meaning a lottery. And I argued that free will is a third state. It is not determinism, of course, but it is also not indeterminism. When a person chooses freely, we assign him responsibility for what he does. That is the meaning of saying that he has free will. If a person just performed some arbitrary lottery, that is not an action whose results you are responsible for. That is something that happened to you, not something that you did. An action that you do is not an indeterministic action; it is an act of choice. And therefore my claim is that at most quantum theory says that random action can also exist in the physical world. But I am looking for a mechanism of free will, not of randomness. And in that sense this is a confusion very similar to chaos. Chaos takes a deterministic phenomenon that cannot be predicted and wants to insert free will into it. That's just confusion. But in quantum theory they want to take a phenomenon that is random and insert free will into it—that too is confusion. Because free will is neither deterministic nor random. It is a third mechanism. And we discussed this at length in previous classes.
Therefore I think there is a conceptual error here. In the end—let me phrase it differently. Suppose I always choose to give charity. My wave function says, for example, that there is a sixty percent chance that I will give charity and a forty percent chance that I won't give charity. So my wave function says that according to the laws of quantum theory, if they check me a hundred times, then in sixty of those times I will give charity and in forty I won't, the law of large numbers. Okay, and what if I choose to give charity a hundred times? Then I deviate from the laws of quantum theory. So that means that in any case I deviate from the laws of nature. So why does it matter if the laws of nature are statistical? You still need to get to the point that choice deviates from the laws of nature, because the distribution that quantum theory determines is a random distribution. But free will means that I decide what I do, not that I hold a lottery. I decide. To decide does not mean to hold a lottery. Therefore I think that even if this interpretation were correct, this analogy—and in a moment I will explain why it is not correct—but even if this analogy between free will and an act of collapse into a state in quantum theory were correct, it still would not explain the concept of free will as we understand it. And therefore quantum theory does not give me a possible platform for inserting choice into physics.
There is another reason for this. I said earlier that Schrödinger's cat experiment was not actually performed, and it's not accidental that it wasn't performed. It's very hard to do such an experiment, even though in description it sounds terribly simple. And why? Because the phenomena of quantum theory exist only on a very, very small scale. I wrote my doctorate on micron scales. At microns this is already considered macroscopic. To see quantum phenomena there is really exotic. I'm talking about ten to the minus six meters, just so you understand—that is, one millionth of a meter, okay? One ten-thousandth of a centimeter, or one thousandth of a millimeter, all right? A thousandth of a millimeter. This is called a huge macroscopic system in quantum theory. And what I did there was not show—not the first to show—but try to do calculations according to a known effect that exists; these are called mesoscopic systems, systems of small size but not too small, okay? Or large but not too large, where there are still quantum phenomena, and to show that you can also see quantum phenomena there. Okay? But in principle quantum phenomena exist at the level of the individual particle. An individual particle is nothing; these are sizes of I don't know what, ten to the minus I don't know how much, ten, twelve meters, okay? Very small things, nanometers or picometers or something like that.
Therefore, at scales—why, for example, does quantum theory say that if we throw a ball at a wall it can pass to the other side? There is some probability that it will pass to the other side. Why do we never see that? Why is it obvious to us that a ball cannot just pass through a wall? Because a ball is a large object. On large scales quantum theory does not work. Not that it doesn't work—it works, but the result is the classical result. Why? Because of the law of large numbers. And again, these are very complicated phenomena, and I am really describing everything here in a nutshell, okay? The claim is—think for a moment about what a large object is. Take the ball. If it were a microscopic particle and I threw it at the wall, it would have some chance of passing through the wall—this is called tunneling, okay? It can pass through the wall to the other side and it can return. There are two possibilities: either it passes or it returns. But when the ball is a large ball, it always returns. Why does it always return? Think of the situation: after all, the ball is a collection of many, many particles, right? Now each particle has some probability of passing, but a greater probability of returning. A small particle, say, will pass forty percent of the time, okay? And sixty percent of the time it will return. Now when I have many small particles and all of them do this together, the probability that they return is one.
Think about a die that you roll. What is the probability that it lands on four? A fair die: one sixth. Can you predict how many times it will land on four if I throw it twelve times? The answer is no. We'll say twice, but there is almost no chance that what will actually come out there is twice. It will come out once, it will come out five, it will come out three; on average it will come out twice, but that is a very poor prediction. But if you throw the die twelve billion times and I predict that it will land two billion times on four, that will be an excellent prediction. This is called the law of large numbers. That is, it turns out that when we repeat an experiment many times, its results converge to the theoretical probability. In a single experiment it's very hard—by the way, these are very common statistical errors—to make a prediction about a single experiment based on statistical calculations; that is often a bad prediction. Very, very problematic, and people are not aware of this—there are all sorts of paradoxes as a result.
Think of it another way. Think now of a container of liquid in which each particle in this liquid can be yellow and can be blue with fifty percent probability. So if you put one particle in this jug, in this cup, then there is a fifty percent chance that it will be yellow, a fifty percent chance that it will be blue, right? Now if you put in two particles, same thing: twenty-five percent that both are yellow, twenty-five percent that both are blue, and fifty percent that one is yellow and one is blue, each time someone else, and so on. What happens when you put in a hundred particles, or ten to the hundred particles if you like? You will always get a green liquid. Why? Because there will be lots of yellow particles, lots of blue particles, and taken together the whole liquid will simply be a mixture of blue and yellow—it will be green. That means that when I gather very many particles, I will not see quantum phenomena. Each particle by itself is either yellow or blue; no particle is green. Each particle is either blue or yellow; it has no green state. But the system as a whole is green. And that is what happens in the transition from small systems to large systems. In small systems there are pathological quantum phenomena—it passes through that slit or through this slit or whatever you want. But when you take a ball, the ball is a collection of many, many small particles. The ball behaves the way we know from classical physics, because the sum of all the quantum probabilities in the end gives Newtonian mechanics. Therefore Newtonian mechanics is still correct today for large bodies. Newton doesn't give up so easily, as we also saw in optics.
So for our purposes, what does this actually mean? The question is on what scales it is relevant for quantum phenomena to exist. In the accepted view—although there are various works trying to argue something else—in the accepted view, one neuron in the brain, which is the individual nerve cell in the brain, we'll talk about that in the next class, the basic unit of the brain, is far too large for there to be quantum phenomena. Far too large. A cell in general, a biological unit cell, is a huge creature in physical terms; that is, there are no quantum phenomena in it in principle. There are many works trying to find quantum phenomena in these systems, but it almost never happens—in fact it doesn't happen. Therefore taking quantum theory and saying that this is a possible explanation for free will within physics is a very problematic statement, because free will takes place on scales that are very, very large relative to quantum theory. It doesn't work on those scales. On those scales there is decoherence, meaning the quantum phenomena disappear. And therefore this is actually interference—by the way, the disappearance of quantum phenomena is interference—and therefore to say that quantum theory gives an explanation for free will is to place it on a scale that is not relevant to quantum phenomena. And as I said earlier, even if it were relevant, it still would not explain, because it would give randomness and not free will.
One final remark in the context of quantum theory. There is some myth, as far as I know at least it is a myth—I haven't been in the field for many years—that human consciousness causes the collapse of the wave function. Wigner did propose this, and von Neumann, and very important and intelligent people proposed this. Penrose too, I think, advocated this for a certain period. All of them, by the way, except Wigner—actually both of them are mathematicians, von Neumann and Penrose—many mathematicians deal with this, and they basically proposed that what causes the collapse of the wave function is measurement because human consciousness is involved here. Human consciousness—this is really telekinesis, right? That by my thought I cause changes in reality. And there are many science-fiction stories and many myths surrounding quantum theory, that quantum theory basically says that human thought causes changes in reality. In the accepted views today, that is not true; it is a myth.
For example, they did an experiment where they placed a detector next to one of the slits in the two-slit experiment, and this detector sent the information to a computer drive—not that a person looked and saw whether the particle passed or didn't pass. This information was burned into a computer's memory, and then the computer destroyed itself. No human consciousness saw this information that the particle had passed through the slit. No interaction with human consciousness whatsoever, and still the particle behaved like a particle. Meaning, the fact that there was a detector there caused it to behave like a particle regardless of human consciousness. Another myth that has to be taken off the table, which serves those same people who want to hang free will on quantum theory. They say that free will is basically human consciousness that manages to bring about the collapse of a wave function that allows several possibilities. Well, no. There is no indication that human consciousness does anything here that something else doesn't do—unintelligible mysticisms, or things that cannot explain this within physics.
So if I summarize, it seems to me that quantum theory also does not succeed in allowing me to insert free will into physics, although if we could then quantum theory really would allow us to remain materialists. That is, one could remain a materialist—the whole world is only physics—and nevertheless support free will. But quantum theory does not allow that. And therefore a person now has to decide between two options: either you are a materialist, and then you must give up free will, not be a libertarian; or you are a dualist, or you are a libertarian, and then you must be a dualist and not accept physicalism, meaning the view that the world is only matter and only physics.
And now we have reached the result at which I will stop the class: what stands before the decision, face to face, the two options between which one must decide, is either a deterministic physicalist view—and now I do indeed connect the question of materialism to the question of libertarianism. Either you say that the world is only matter and physics and then there is no free will, or you say that there is another dimension in the world, and then free will may be possible. May be, not necessarily, because it may be that it isn't. So now we really have connected the question of materialism to the question of determinism. Because now we have seen that physics, if we accept physics, does not allow free will. So if you are a materialist and you think that the laws of physics determine everything, free will cannot be possible. And therefore if I now settle the question of materialism or the question of libertarianism, I have done the same work. All right? So that's what we'll get into in the next class, where we'll begin working on neuroscience and on how, through neuroscience, we examine this issue, and after that it will take us a few meetings, and after that I will summarize and that will be the end of the series.
[Speaker C] Just one remark: today there is a field called quantum biology dealing with all sorts of things.
[Rabbi Michael Abraham] That's what I meant, yes, that they say that even on the biological scale there are quantum phenomena. By the way, it's also important in connection with evolution, because evolution also assumes that there is randomness in the emergence of mutations.
[Speaker H] And the question—
[Rabbi Michael Abraham] How can there be randomness if physics is deterministic? So there too they want to claim that at the level of DNA there are some quantum phenomena. I don't know exactly where that stands; I am far from being an expert in that field. But as far as I know, it still doesn't really make it possible to explain free will. And here I really say this with reservation, because I don't fully understand it. I said, in any case it still isn't free will, because even if there can be quantum phenomena at the biological level, that will give me randomness, not choice.
[Speaker C] Okay, that's the first point.
[Rabbi Michael Abraham] Yes, and therefore I say that in any case, for our purposes, it's not all that important.
[Speaker E] Even if we say that it doesn't explain the issue of free will with certainty, maybe it somewhat weakens the arguments against free will—quantum theory somewhat weakens them.
[Rabbi Michael Abraham] Correct, I'll get to that at the beginning of the next class. I really may add one more remark about that: the question whether free will can hide because of quantum theory. Not be explained by quantum theory, but quantum theory allows us to explain that maybe there is free will and we don't sense it. Right, exactly. So I'll deal with that. Fine. Okay. Anyone else? For me—
[Speaker B] There’s a question that’s a bit more connected to last week. We said that if a person raised his hand out of choice and will, then we see that as contradicting physics, because there’s some spiritual factor that started some chain of electron transfer and somehow entered this world. And we said that if we accept that will affects the body, then we’re giving up the laws of physics. But when you spoke about the opposite direction—say you get hit in the leg and you feel pain—then that doesn’t contradict the laws of physics, and I wanted to sharpen why.
[Rabbi Michael Abraham] Physics—does physics forbid the physical world from causing non-physical things? I don’t know of any such law in physics. Physics forbids non-physical things from affecting physics, because it claims exclusivity. But physics says nothing about non-physical things.
[Speaker B] Isn’t that like—it’s not the reverse of saying that will causes some movement of electrons?
[Rabbi Michael Abraham] So the opposite direction? No, not at all. When you say that will causes the movement of electrons, you’re basically saying that this electron moved even though no physical force acted on it. That contradicts the laws of physics. But when you say that I felt pain because I got wounded in the leg, there are no laws of physics that say what causes pain. Pain is not in the domain of physics.
[Speaker B] Right, that’s it—for me it sounds like this side says that the last stop in the chain of electron transfer is, say, the soul, and that doesn’t seem logical to me.
[Rabbi Michael Abraham] No, not at all. The last stop from the standpoint of physics is the physical world. But physics does not determine that there are no further stops after that, ones it doesn’t deal with. That’s unrelated. There’s no contradiction here. No law of physics is being violated here. In the effect of will on
[Speaker H] a particle, the second law of Newton is violated. Simply put, Newton’s second law is not correct if will affects a particle. But if the particle affects the will, what law does that contradict? No law. At most, it contradicts an assumption of physicists who are materialists, but their assumptions are their own responsibility; they are not laws of physics. Anyone else? Okay, we’ll stop here. Sabbath peace. Sabbath peace, more power to you.