The missing fourth circuit element

24:36access memory. And to understand that, we really have to understand something called the memister. Okay. Okay. Let's go back to 1970. There are three types of fundamental circuit components. The resistor, the inductor, and the capacitor. This is the stuff of undergraduate physics. And if you're an electrical engineer, I'm really sorry for your loss, but you probably you probably deal with this every single day, right? Um, a resistor is something that resists electric current. So, it drops a voltage across a resistor. And um, an inductor is something that takes a changing current and creates um,

25:17another current that's going in the opposite direction. So, it kind of stores energy using a change in current. And a capacitor is something that stores energy using charge. Okay. Now, Leon Chua in 1971, he was at UC Berkeley, he said, let's look at these three components that we've got. We've got a capacitor, right? A capacitor is something that has a relationship between charge and voltage. If I store a bunch of charge, that stores a voltage difference. I've got a resistor. That's a relationship between voltage and current. Right? As current goes through, there's a voltage drop. And I've got an inductor. That's

25:58something that has to do with current and magnetic flux. Okay? There's four variables, though, >> right? >> And there's only three components, right? So, for those who may be audio listeners, we're looking at a square. It kind of looks like those uh those one, two, three, four. I don't know what you call. >> Oh, the Yeah. Yeah, the thing we used to do in elementary school that would tell me like what my fate was. >> Yeah, the paper thing. Yeah, >> you can let us know in the comments. But but on each of the four sides you have exactly the components you mentioned and each of the four corners you have the charge, voltage, current and flux. And

26:38the point here being we've talked about every relationship but one side of the square >> but one side of the square right there should be Leon Chua decided there should be a relationship between flux and charge the flux capacitor >> in some sense. Yeah. Yeah. And he deemed this thing the memortor he said there should be something out there. Okay. This is a component where the resistance changes dynamically based on the charge flow. and he he ruled that if there is such a relationship what this thing is going to do is it's going to remember the state when the power is off. Okay, let's the telltale sign. He he also showed okay if if experimenters are

27:19looking at this thing, he was a theorist and he said if experimenters are looking at this thing, all you got to do is look at the IV curve. Okay. The um the IV curve is the current and the voltage >> on the two axis. >> Voltage on the axis. >> Yes. Okay. And if we look at the IV curves, they're all very unique. On the top left, that's a normal resistor. Okay. As I increase the voltage, I'm going to increase the current across the resistor. And there you've got a line. This is a nonlinear resistor. A linear resistor would be like the stuff that we do in undergrad physics is just like, oh, V equals IR. That's not entirely true, right? The R is a function of the

28:00V. So it there's going to be like some nonlinear resistance where like at low voltage the resistance is not that high and then at high voltage the resistance is way higher. Things like that. Um or maybe no it's the other way around. At high voltage the resistance is lower because you know there's more pull. So like the it's easier to shuttle electrons through. Okay. So that's what we're seeing in the top left corner. Okay. On the top right corner and the top in the bottom left corner we're seeing the IV curves for a capacitor and an inductor. Okay. Those things cycle around those things. And this is something that everyone knows from, you know, if you've ever done RC circuits, you'll you'll know that there's an

28:41oscillation that happens in RC and RL circuits. Especially if you if you combine a capacitor and an inductor, the capacitor gets charged and the inductor doesn't get charged and then the inductor gets charged, the capacitor gets discharged. So there's a cycling that happens and that is something that is characteristic of like s and cosine. You got the unit circle, the x-axis is s, the y-axis is cosine. Great. Leona said, "I should be looking for something called a memortor where charge and magnetic flux are related to one another. And what I would see is a curve that looks like a loop, a figure 8 loop.

29:24And the challenge is there is no way to combine the other three curves to get that fourth curve. >> Interesting. >> Okay. It is an independent element in electronics. >> It's it's fundamental. It's not derivative. >> Yes. Exactly. You know what? You see what I'm saying? It's like [clears throat] it's like you can't make you can't make an electron out of quirks. >> Right. >> Right. Similarly, you can't make a memory by just cleverly placing resistors, capacitors, and inductors together. This is an independent component that is one of the four fundamental components of electronics. >> And this sort of goes back to our previous visual, which you know in this

30:05context of those four parts, you needed this is sort of the missing piece to the puzzle of the fundamental elements. >> Yeah. And it's just a mathematical argument >> which is so >> which is so cool to think about right that it's just like there's there's four variables we've only got three components there should be a fourth one theorists have value everybody okay >> it's it's very cool and one more thing I want to say about the memor IV curve right um notice that for a capacitor and an inductor at zero voltage there is a nonzero current okay that means it can't store data Because if I turn the thing off, there's going to be current and

30:46that's going to dissipate whatever the the stuff was happening, right? A resistor could store data because at a zero voltage, there's zero current, but it only stores a one. It's whatever the resistance is. So, it's not really storing anything. If we go back to Claude Shannon's um information theory, I need two things to store data. I need a zero and a one. >> A memory, on the other hand, at zero voltage, it can be in two states. It can be in a low resistance state or a high resistance state. >> This is so good. This is so good. >> Now all of a sudden people start paying attention because this could be a substrate for nonvolatile memory. Meaning I turned the thing off. But

31:26depending on the history of where I was on the curve, I could be in either a low resistance state or a high resistance state. If I can sense that, that's my 0 and one computers. >> As a quick uh visual analogy here, cuz we're basically looking at this figure 8 that's kind of like a racetrack. You remember Hot Wheels as a kid? >> Yeah. >> So, you remember how you could have the you could have a figure eight like that, but one side would be going under and then it would come back and it would be going over. And that's kind of what we're saying where it can be in two states at that center point. It can be on the top part of the Hot Wheels track or on the bottom part of the Hot Wheels track. And that's that mechanism is how we're storing the zero and one. How we're able to have two states, which means we can have a zero and we can have a one. >> Exactly. Yeah. And for the Formula 1

32:06fans, the only circuit that does this is Suzuka in Japan. It's the there's a figure 8 that's beautiful. One day we'll go. Um, so the theorist has done his job. He's like, there should be this thing and specifically this is what you guys should look for. >> Um, it takes 40 years.