Transcription
You know, I've spent a lot of time thinking about thinking, not in some abstract philosophical way, but in a practical sense. How do we actually know when we understand something? Because here's the strange thing. Most of us walk around believing we understand things that we don't really understand at all.
Let me tell you what I mean. A few years ago, I was at a dinner party and someone asked me to explain how a refrigerator works. Now, I'm a physicist. I should know this, right? So, I started talking about thermodynamics, heat pumps, compression cycles, all the technical stuff. And then I stopped myself mid-sentence because I realized something uncomfortable. I was using words I knew, sure, but I wasn't actually explaining anything. I was just reciting. If that person had been a child or someone with no background in physics, they would have been completely lost. And that bothered me. It bothered me because I had confused knowing the name of something with knowing the thing itself.
This happens all the time. We learn vocabulary. We learn formulas. We learn to recognize patterns and we mistake all of that for understanding. But understanding is something different. Understanding is what's left when you take away all the fancy words.
So I started doing something that changed the way I learn everything. I started pretending to teach. Now, I don't mean I stood in front of a classroom every time I wanted to learn something new. What I did was simpler than that. Whenever I came across an idea I wanted to understand, really understand, I would find a blank piece of paper and I would write out an explanation as if I were teaching it to someone who knew nothing about the subject. Not another physicist, not a colleague, someone who had never heard the word thermodynamics or momentum or entropy, a curious person with no technical background, maybe a bright 12-year-old.
And here's what happened. Every single time, without fail, I would get stuck. I'd be riding along, feeling confident, and then I'd hit a spot where I'd write something like, "And then the system reaches equilibrium because" and I'd stop. Because what? Why does it reach equilibrium? I thought I knew, but when I tried to explain it in plain words, I realized I didn't. I had a vague sense of it. I could use it in equations, but I couldn't explain it.
That moment, that uncomfortable moment of getting stuck is the most important moment in learning. Because that's the moment when you discover the difference between what you actually understand and what you only think you understand. Most people avoid this moment. When they hit that wall, they tell themselves, "Well, I understand it well enough." Or, "I don't need to know it that deeply." And they move on. But that's exactly backward. That wall is where the real learning begins.
What I do when I hit that wall is simple. I go back to the source. I open the textbook again. I reread the section I thought I understood, but now I'm reading it differently. I'm not reading to collect information. I'm reading to fill in the specific gap I just discovered. I'm reading with a question in mind, and that makes all the difference. You see, the first time you learn something, you're trying to absorb everything at once. It's overwhelming. But when you go back with a specific question, why does the system reach equilibrium? You're like a detective looking for one particular clue. You read past all the stuff you already understand, and suddenly you see the sentence or paragraph that answers your question. It jumps out at you and now you really get it because you needed it.
Then I go back to my blank piece of paper and try again. And I get a little further until I hit another wall. And then I go back to the source again. And I do this over and over until I can explain the whole thing start to finish in simple language that anyone could follow.
Now, you might think this sounds tedious, and sometimes it is, but here's what I found. It's actually faster than the way most people study because most people read through their textbooks or their notes multiple times, highlighting things, making flashcards, trying to memorize. They spend hours and hours and at the end of it, they still don't really understand. They've just become better at recognizing the material when they see it. But when you use this method, when you force yourself to explain it in your own words, you're doing something much more powerful. You're not memorizing someone else's explanation. You're building your own understanding from the ground up and that kind of understanding sticks. You don't forget it the week after the exam. It becomes part of how you think.
Let me give you an example that has nothing to do with physics because I think this applies to everything, not just science. Let's say you want to understand how democracy works. Not just the definition. You can look that up in 10 seconds, but really understand it. How do you do that? Well, you could read books about democracy. You could learn about the separation of powers, checks and balances, representative government, all of that, and you might feel like you understand it. But try this instead. Take out a blank piece of paper and explain to an imaginary person why democracy tends to work better than dictatorship, not using political buzzwords, not quoting the founding fathers. Just explain it in your own words from first principles.
You might start writing something like democracy works because people vote for their leaders. Okay, but why is that better? Because then the leaders have to do what the people want. But do they? What stops them from ignoring what people want once they're elected? Well, they'll get voted out next time. But what if they change the rules so they can't be voted out? What stops them from doing that? See what's happening? You're finding the gaps. And those gaps are where the interesting questions live. Why do we need an independent judiciary? Why is freedom of the press important in a democracy? Why do we need peaceful transitions of power? These aren't just abstract ideas. They're solutions to specific problems that you discover when you try to build up the concept from scratch. And when you go back and read about democracy now after you've struggled with these questions yourself, everything makes sense in a way it didn't before. You're not just memorizing facts about democracy. You understand why it's structured the way it is.
This is what I mean by the difference between knowing the name of something and knowing the thing itself. Knowing the name is easy. Knowing the thing requires work, but it's the kind of work that actually gets you somewhere.
Now, there's another piece to this that I think is crucial. When you're explaining something in simple language, you can't hide behind jargon. Jargon is useful. Sometimes it's a shorthand that lets experts communicate efficiently. But it's also a trap because it lets you fool yourself into thinking you understand something when you're just familiar with the words. I'll give you an example from my own field. In quantum mechanics, we talk about wave function collapse. Students learn this term. They use it in equations. They can pass exams on it. But ask them to explain what it actually means, what's really happening physically. and most of them can't because they've learned to use the term without ever building a real mental model of what it represents. The same thing happens in every field. In medicine, doctors talk about idiopathic conditions. Do you know what idiopathic means? It means we don't know what causes it. But it sounds much more impressive than saying we don't know. In business, people talk about synergy and optimization and leveraging core competencies. What do those phrases actually mean? Often nothing very specific. They're just comfortable words that let you avoid the hard work of precise thinking.
When you force yourself to explain something without jargon, you can't do that. You have to actually understand what's going on. And if you can't explain it simply, that's a sign. It's a sign that you don't understand it as well as you think you do.
Now, I should tell you this is humbling. When I first started doing this seriously, I was shocked at how many things I thought I understood but actually didn't. I'm a physicist. I've won awards. I've taught at universities. And yet, when I sat down and tried to explain basic concepts in simple language, I found holes in my understanding all over the place. But that's good. That's the point. The goal isn't to feel smart. The goal is to actually be competent. And competence comes from being honest with yourself about what you know and what you don't.
There's something else I've noticed about this way of learning. When you understand something deeply enough to explain it simply, you start to see connections you didn't see before. You start to notice that the same basic principles show up in different contexts. The way a refrigerator works isn't really all that different from how an air conditioner works or how a heat engine works. They're all just moving energy around using the same basic ideas. And once you really understand those basic ideas, you can figure out new situations without having to memorize every specific case. This is what people mean when they talk about first principles thinking. Though I don't love that phrase because it sounds fancier than it is. It's just understand the basics really well and everything else gets easier.
I used to have students come to me and say, "Professor Fineman, I've read this chapter three times and I still don't get it." And I would ask them, "Have you tried writing out your own explanation?" Usually, they hadn't. They thought reading was learning. But reading is just the first step. Understanding comes from engaging with the material, wrestling with it, trying to reconstruct it in your own mind. Sometimes they'd say, "But I don't know enough to explain it yet." And I'd tell them, "That's exactly why you should try to explain it." Because trying to explain it is how you find out what you don't know. You don't wait until you understand something to explain it. You explain it in order to understand it. It's like the old saying, you don't really know something until you can teach it. But I'd go further than that. You don't really know something until you can teach it to someone who doesn't already speak your language, who doesn't already share your assumptions. That's the test.
And here's what I find beautiful about this. It works for everything, not just academic subjects. You can use this to understand how your car works or how the economy works or how your relationship with your spouse works. Anything that's worth understanding is worth trying to explain in simple terms.
Let me tell you about one more thing I've noticed. When you explain things this way, you often end up with an explanation that's different from the textbook. Not wrong, just different. You come at it from a different angle, use different analogies, emphasize different aspects, and that's fine. In fact, that's better than fine because that explanation is yours. You built it. You understand why every piece is there because you put it there yourself. This is the opposite of what most education does. Most education tries to give you someone else's understanding already packaged and complete. Read this. Memorize that. Here's how to think about it. But understanding doesn't transfer that way. You can't just download someone else's understanding into your brain. You have to build your own.
Think about it this way. If I wanted to teach you how to cook, I could give you recipes. I could tell you exactly what ingredients to use, exactly what temperature, exactly how long to cook it. And if you followed my instructions precisely, you'd probably make something decent. But you wouldn't really know how to cook because the first time something went wrong, you didn't have one of the ingredients or your oven runs hot or you wanted to make twice as much, you'd be lost. But if instead I taught you about how heat changes proteins, how salt enhances flavors, how fat carries aromatics, how acid balances richness, if I taught you the principles, then you could figure things out yourself. You could improvise, you could create, you wouldn't need my recipes anymore. That's what this method of learning does. It teaches you the principles. It forces you to understand how things actually work, not just what steps to follow.
And here's the thing, this isn't just useful for learning subjects. It's useful for living. Because life constantly throws situations at you that aren't in any textbook, new problems, unexpected challenges, things you've never seen before. And if you've spent your life memorizing other people's solutions, you're not prepared for that. But if you've spent your life understanding how to think things through from the ground up, if you've practiced breaking things down and building them back up in your own words, then you can handle novelty. You can figure things out.
I think this is really what education should be about. Not filling people's heads with facts, not training them to pass tests, but teaching them how to think, how to question, how to understand, how to be honest with themselves about what they know and what they don't. And it starts with something as simple as a blank piece of paper and a willingness to admit that you might not understand something as well as you thought. That's all it takes. That willingness to be wrong, to be incomplete, to be still learning.
Because here's the secret. We're all still learning. Every one of us. The smartest person in the world is still confused about most things. The difference is just that some of us admit it and some of us pretend we're not. I spent my whole life being confused. Still am. But I've learned to be comfortable with that confusion because I know it's temporary. I know that if I sit down with a blank piece of paper and work through it step by step in simple language, eventually it'll make sense. Maybe not today, maybe not this week, but eventually.
That's the real lesson here. I think understanding isn't magic. It's not something you're born with or without. It's just work. Patient, humble, honest work, trying to explain something, finding where you get stuck, going back, trying again over and over until it clicks. And when it does click, when you finally really understand something, when you can explain it clearly and simply, when you can see all the way through it, that's one of the best feelings in the world. Not because it makes you special, but because it means you've done something real. You've added something to yourself. You've grown. And you can do that with anything at any age. You never stop being able to learn. You just have to be willing to pick up that blank piece of paper and start writing.