#73 Steven Strogatz: Exploring Curiosities｜The Knowledge Project

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Today I'm talking with Steven Strogatz, professor of applied mathematics at Cornell University.

I wanted to talk with Steve after reading his most recent book, Infinite Powers, which explores how calculus unlocks the secrets of the universe.

Together we'll explore how math helps us better understand the world and make better decisions and as you'll see, Steve makes learning things fun and practical.

Let's get started. It's time to listen and learn.

How did you get interested in math?

Was it a story that pulled you in?

Were you innately interested in it?

Was it something like a teacher?

How did this happen?

Well I was interested in all of school and I still am.

I like all the different subjects.

So math didn't stand out for me.

I'd say really pretty much for most of my childhood.

It was just one among many.

But then I do remember one or two moments where it started to take special significance.

One was I had two friends when I was about, well let's see, we used to call it junior high school.

So it was 7th and 8th grade.

I must have been about 12 years old.

Two other boys and they were both good at math and vocabulary and geography and everything else.

I used to like to compete with them.

We would play chess against each other and other things and at that age just being better than your friend meant a lot to me.

I don't know. Or having them feel better than me inflicted a kind of pain.

So I do remember one time getting a little higher score than this other kid on a math exam and it just felt good.

So I'm not saying this is a noble reason to be interested in math but it was just an early memory that it was very objective.

You could say I'm better than you and it actually meant something which to a 13 year old boy that was important.

But on a more elevated level, I'd say the real turning point was in my, it would have been my sophomore year of high school.

So by then I was about 14 or 15 and a teacher said something that took me aback.

I had never heard any teacher say something like this.

This was Mr. Johnson who had a beard and had gone to MIT and to me he looked like what I imagined a brilliant math professor might have looked like.

He was very serious, not a smiler but fair and he said that there was a certain geometry problem that he had never seen any students solve.

Just off -handedly mentioned it to the whole class and I thought that was interesting because I had always been able to do any geometry problem.

Any teacher asked me.

So he said, yeah, he didn't, no one had ever solved this certain question and then he also said that he didn't know how to solve the problem and that was very surprising because I had never heard a teacher say that.

He didn't know how to do the problem so I started thinking about it.

I could tell you the problem in case you're ...

Yeah, please do. It was a question about a triangle that sounded like many other geometry problems.

It says if the angle bisectors of a triangle are congruent, prove the triangle is isosceles.

So what that means is angle bisectors, that would be a line that cuts through the angle, so picture a triangle like say standing there flat on the table with its point sticking up.

If you divide the angle in half at the base, there are two of them down there.

If they're divided in half by a line and then that line meets the opposite side of the triangle, that's the angle bisector and so if you have two of those crisscrossing and they're equally long, that's what congruent means.

Two angle bisectors of equal length prove that the triangle is isosceles, meaning that those two angles at the base are actually the same angle, have the same number of degrees.

It sounded like many other questions, there are similar questions, if two perpendicular bisectors are congruent or something called medians.

All these questions are pretty easy to prove that you would get an isosceles triangle, but something about angle bisectors made the question very hard and when I tried it, I couldn't do it.

That already caught my interest and I worked on it a lot.

I spent a day or two on it, I still couldn't do it and then days became weeks and weeks became months and I think I spent about maybe six months on this question.

Trying things, getting stuck, trying other things, getting stuck.

Sometimes it would come close to working out, but I could never get the argument to go all the way through.

My friends would get annoyed with me, like, come on, let's go to a movie.

No, I feel like thinking about the angle bisectors.

Or in French class, we used to have this conjugation train where the teacher would give some verbs to conjugate and you'd feel that it'd be going around the room and you could feel it's going to be my turn soon.

But I was still thinking about the angle bisector.

So I was obsessed with it and I didn't realize it at the time, but I was doing research where I was thinking about something for just the pure pleasure of trying to understand it.

And ultimately, I got something that I thought was a proof.

It was a boarding school.

My teacher lived nearby and I asked if I could come over to his house on a Sunday morning.

I could still remember him there in his beard and his pajamas and his little kids running around in his house at breakfast.

He checked this proof line by line very slowly and, you know, with his serious stern face, said, well, yes, that's a correct argument, very good.

And then he wrote a little note to the headmaster of the school, which meant a lot to me that, you know, my teacher said something like, Steven has real talent.

You know, so I don't know, it just, it was definitely a pivotal moment.

It's interesting, like, what a difference a teacher can make.

Yeah, of course. I mean, partly that he really set the bar very high, but also he was humble, you know, he was strong enough to admit there was something he didn't know.

And apparently, he may probably mention that in other years and other students hadn't either risen to the challenge or weren't interested.

Why would you do homework if you didn't have to?

But something about it caught me.

And yeah, he was a very inspirational teacher.

And it's interesting, too, that he's not the Hollywood inspirational teacher.

It wasn't like, you know, such a loving, sweet guy, or certainly not interested in building your self -esteem.

He was just all business.

But there's a line in that movie about another great teacher, Stand and Deliver, about Jaime Escalante, who taught in East Los Angeles, who says in one critical scene in the movie, the students will rise to the level that the teacher expects.

And so if the teacher expects something really hard, kids don't even know it's impossible.

They'll try. I try to do that myself with some of my students.

And what do you see?

Does that prove out?

Sometimes it does, especially younger ones.

You can really, you know, by the time they're seasoned, if they've been in college a few years, they start to know the game.

But freshmen don't really know what college is going to be like.

And so you can do mercilessly unreasonable things to the bright freshmen in math.

And they will astonish you with what they can do.

Yeah, we see that all the time.

You didn't have an easy path in math though.

Was it first year university where you sort of got the worst grade you've ever gotten and you switched to physics, or was that, when was that?

That is true. That was my first year.

Well, that was that class.

So I was just describing how our freshmen, the first year students can do astonishing things.

I was supposedly one of those students when I went to college, so they grouped a bunch of us together in like whiz kid linear algebra.

And for this was for all the kids who had done extremely well in calculus in high school.

So we, and it's sort of like you had a little, a mark on your head, this is a future professional mathematician or at least potential to be.

And the other thing though, is that professors know that kids who are good in math and high school, a lot of them are going to get, so to speak, weeded out.

They don't really have the right stuff to be mathematicians of the future.

At least that was the thinking at the time.

It's a pretty nasty pedagogical philosophy, I must say.

But they would throw all of us in with one of the worst teachers in the school.

I don't know why they assigned him to us.

I mean, this was a really pathetically terrible person for teaching.

I mean, the first day of class, he came in and sort of slithered along the wall, didn't make eye contact with the students.

A very shy person who didn't say welcome to Princeton, welcome to the, you know, this is going to be exciting.

Nothing. He just started with the definition of the key ideas at the beginning of linear algebra, the definition of a field, blah, blah, blah, here are the axioms it satisfies.

Anyway, extremely dry and I couldn't understand what the heck was going on.

And the textbook had no pictures and as a visual thinker, I found that very problematic.

I couldn't really understand what was happening and weeks would go by.

I could feel myself falling behind and not, you know, my homework was getting worse and worse grades and I didn't know certain basic things like, well, try reading a different book, you idiot, or go ask for help from the teaching assistant.

I didn't know. I had never done that stuff before, so it didn't occur to me.

I thought I should be able to understand and I was having trouble.

And so I did end up getting a B minus, which was a pretty low grade and I wish I had your transcripts.

Well, okay, but it was a low grade and it was discouraging because I didn't deserve a B minus.

I really knew that I knew nothing.

I probably should have failed, but they didn't want to do that for some reason.

So it was a really, yeah, very demoralizing experience and it made me think, wow, maybe I don't have the right stuff for this.

Maybe math is different in college.

I stuck with it for one more semester and took a second course in that same whiz kid sequence honors, this time honors, multivariable calculus and I could feel the same thing was happening again in that second semester.

I was on track for another lousy performance.

Well, and meanwhile, I saw other kids doing fine.

I mean, they were raising their hand.

They seemed to know everything.

So even in a relative sense, not just an absolute sense, I could see that I was weak compared to the people around me.

And it was a formative experience because I think it's given me a lot of sympathy as a teacher.

When I see students struggling, I don't always assume that they're hopeless or they can't be rescued or they have no future.

In my case, I mean, it has stuck in my craw now 40 years later.

When I teach linear algebra, I realize it's not really that hard.

You can do better than my old teacher did.

Show some pictures, give some intuition, talk about how it's connected to the real world, tell some history, bring it alive, Jesus.

It's a really exciting subject.

You don't have to suck all the blood out of it.

So I also the idea of being made to feel like a weed.

You hear this idea of weeding out the people who have the right stuff from those that don't.

I really don't accept that idea.

People have a lot of potential more than that kind of superficial analysis would lead you to think.

So I was practically – I could have easily been weeded out except that I just love the subject so much.

I stuck with it even though I was always one of the weakest math majors in my cohort.

I just loved it more than most.

That's a fascinating story.

It strikes me that math is something that we develop this mindset about for whatever reason that we're just not mathematical or math isn't my strong.

This sort of happens around grade four, five or six and it sort of follows us.

Is that a teaching thing?

Why do most of us find math so boring and dry?

You're right about that, aren't you?

If you just look around and ask your friends, the average person did not have a good experience in math class.

Although it tends to be a little more complicated than that.

Most people will say, I did like math until, and then they'll tell you until we got to fractions.

Those were really confusing with the common denominators.

Or I liked it until we got to algebra and then it was all those X's and Y's instead of numbers and I didn't really know what was going on.

I even liked algebra but then I lost it in geometry or I hit the wall in calculus.

Different people have these different places but it seems it sort of happens to everybody at some point or almost everybody.

Why? There's a few explanations.

One is that the subject, the way it's traditionally taught is made to seem like a tower.

Each thing builds on the topic before it and if you fall off at any stage, it's a long way down off the tower.

It's a very linear architecture whereas the reality is that math is a web not a tower.

You can jump in at different points in the network of ideas and then find your way around from there.

It's not really true.

It's complicated. In some ways it is sort of like a tower.

The idea of algebra and variables and functions and I know you know computer science so you will know what I'm talking about here.

Those are fundamental ideas.

If you can't think abstractly about a variable rather than a concrete number, you're going to have trouble with a lot of math because that's a fundamental idea.

If you don't get that, pre -calculus is going to be trouble.

Algebra too is going to be trouble.

Some things are indispensable but there are other things which, okay, maybe you missed the idea of an asymptote.

You can still keep going without that.

There's that. It's partly the structure of the subject.

Partly it's often taught in a very top down way.

The teacher presents material almost like pouring liquid into a student's head.

It's almost like a curriculum dump too, right?

It's like we have to cover all of these things and we're going to start here and we're going to progress and I don't care if you're interested or not.

This is the standard curriculum.

You've hit a bunch of important things there.

One is the feeling that there's a lot to cover.

I once heard a teacher say, don't try to cover the material.

Try to uncover it. There's a lot to be discovered, a lot to be uncovered.

To remove the fog, to remove the crust of difficulty or misunderstanding.

Reveal something rather than cover it.

Okay, that's just a silly use of the word cover and uncover, but the notion that there's a standard curriculum sometimes stifles exploration.

There is a certain amount of exploring that even a very young student can do.

The experience of being a mathematician is so different than that of being a student, where we're frequently in the dark and we're poking around and trying to make sense of some new territory, mathematical or mental territory, and you're an explorer.

You're lost, you're in the jungle, how do you get out or how do you make progress?

That's a very valuable skill in all aspects of life when there's uncertainty and sometimes fear, but excitement, exhilaration, the thrill of problem solving and inching your way forward applies to everything.

We could be spending more time on that rather than here's an established body of techniques that you have to learn and I'm going to dump it or pour it into your head.

That's a very artificial picture of the mathematical enterprise and why do we do it?

I don't know. I mean maybe there's all kinds of standardized testing.

The teacher has to get through certain material to satisfy local authorities or because tradition says this is what an educated person needs to know and there's some truth to that.

I don't know. I don't have an easy solution to this, but times I've taught courses with this more exploratory mode where there was no place we had to get to.

We just had to do the process in an honest way, the way a real mathematician would do it.

Students love that.

Math is not boring then.

That's creative. Oh, yeah.

I would love that. Yeah.

Well, we do that. I teach a course called Math Explorations with students who are required to take a math course before they graduate and they dread it.

These are the people who are the real dead enders.

They're putting this off until their last year of college, but they have to get out.

They have to go through it to graduate.

Then once I teach it this way with them doing explorations together, activities, working in groups and thinking and sharing ideas.

Can you give me some examples of the stuff that you cover?

Oh, yeah. Sure. Here's one.

We're used to a standard kind of geometry, but there are other geometries.

Here's an example. Suppose we're in New York City or some other city that has a grid of streets.

If I say, how far is my location from some other location?

You could say it in terms of miles or kilometers as the crow flies, but that's not very relevant if you're driving on the grid.

You might be more likely to say you have to go three blocks north and eight blocks west or something like that.

You would give units of blocks as measured on the grid.

That's an interesting kind of geometry.

If you define the distance between two points in a plane as being the number of units north south plus the number of units east west, you can define a distance like that.

It's not the Euclidean distance.

It's not the standard one because you're not allowed to take diagonal paths in this geometry.

You can only go on the grid.

Now if you ask someone a question like what does a circle look like in this geometry?

That's an interesting question.

In other words, what's the set of all points three blocks away from a given point?

Try to picture that in your head.

You could go three blocks north or you could go two blocks north and one over, either east or west.

You could go one up and two over.

If you can picture what those points look like, I don't know.

Are you picturing it?

I'm trying to, yeah.

Do you want to draw?

Do you have a piece of paper in front of you or anything?

Or maybe you have it in your head?

I have it in my head.

Okay, you want to say?

Or should I not make you do that?

No, no. I'm already going to embarrass myself enough in this conversation.

Okay. All right, then I'll say.

If ... okay, well, it should look like a diamond.

I mean, it should look like a tilted square.

Okay, so when my students discovered that, one person started screaming.

She was saying, that's wrong.

That can't be right.

That's crazy. So I said, what's the problem?

She said a circle is round.

This thing has points.

I mean, this has corners.

This doesn't look round.

So I said, well, who says it should be round?

Just because the Euclidean circle is round in traditional geometry, this is a new world.

We're making new rules.

This doesn't have to ...

who says it has to look round?

It doesn't look round.

So and then you can do more.

You could say, what is pi?

Calculate pi in this geometry.

Now, that takes you back to fundamentals again.

Well, what is pi? I mean, some people have memorized 3 .14159 like that, but that's just memorizing.

That's not thinking.

Thinking would be, what does pi actually mean?

It means the ratio of the circumference of a circle to the diameter of a circle.

And so with this diamond shape, you have to now think.

If I measure the circumference ...

Can you take this point, like assume nobody knows anything, including myself.

So circumference is the area around the circle and the diameter is the width of the circle?

That's right. Exactly.

Good. Right. So the circumference would be just that.

It's the distance you would travel if you moved around the circle, the total distance following the circle around on its rim.

And exactly. The diameter is the widest distance across the circle.

So, you know, again, you have to try to calculate that or see what it would be, for my little example, with the circle of radius three in this funny geometry.

And the radius is the point from the middle of the circle to ...

It's a half the diameter, I'm guessing?

That's right. Sure.

That's right. The radius would be half the diameter.

So from the center of this ...

It's been a long time since I did this.

Good. Okay. I'm glad it's coming back to you.

So, I don't know. I mean, maybe it's not so good to do it in this audio format.

But I'll tell you, the answer comes out to be four.

Okay. If you calculate the circumference and you calculate the diameter, you'll end up getting that they're always in the ratio ...

I think I'm doing it right.

It's always going to be four times the diameter will be the circumference, which is interesting.

The pi is actually a whole number.

It's four in this geometry instead of 3 .14.

So, I mean, okay. What's the use of this?

It's not like it's so important to have the geometry forgetting around cities with grids.

It's just to make the point that this is a playground.

This is the realm of the human imagination.

You can think of alternative geometries and explore them.

And the point being, it's very empowering.

The students feel, hey, I can do this.

I mean, I don't tell them the answers.

The whole course is based on me never lecturing.

I just give them puzzles.

And then they try to figure them out.

Yeah, they do. And they do figure them out.

And if they're stuck, I say, okay, let's figure out what to do.

I mean, now you're stuck.

What are you going to do?

And then people learn how to get unstuck, which is really valuable to have problem -solving strategies for coping with frustration.

We also talk about emotional stuff, like, okay, we're stuck.

How does that feel?

Well, I'm frustrated.

I'm mad. I'm curious.

Whatever. And people talk.

Now, there's a lot of people these days criticizing the notion of safe space.

You hear this, that this is like a snowflake thing.

Okay. We shouldn't talk politics.

But I'm sure your listeners know what I mean, that you hear about in education, especially higher ed, that there are things that we're not supposed to talk about because it triggers people.

And this is a safe space where we're not going to trigger anybody.

And that's usually presented as a very negative thing that stifles free speech, et cetera.

But I want to bring up the possibility, because I've lived it with these students, that when you make a space that is safe for mathematical confusion, meaning nobody's going to feel stupid here, we're all confused.

Confusion is the normal state of affairs when you're trying something really hard and when you're exploring the unknown.

So it is a safe space in the sense that you can trust us, that we're all on the same team trying to figure this out together, and don't worry about looking stupid.

I'm confused over here, too.

That sounds like a great environment.

It is. It is. And when you collaborate on research at the cutting edge of math, where nobody knows the answer.

I mean, you can't look it up.

You can't ask a professor because no one knows.

And it's the same thing with science or any other thing at the cutting edge of knowledge.

When you're collaborating, it really helps to be vulnerable and to have a safe enough relationship with your collaborators that you can say, I don't get this.

Could you go over that again?

Or I don't see what to do?

Or to suggest a stupid thing that someone else, rather than jumping down your throat?

Or they could tease you.

Maybe they do jump down your throat a little.

But it's ultimately safe to take intellectual risk.

That's the point. As you were saying that, I remembered a momentary panic.

One of my kids brought home some homework last week and I was looking at it going, oh my gosh, I don't know how to do this.

And I was sort of like, what does that mean?

Does it mean he's going to think less of me?

Does it? I mean, both my kids are pretty good at math, but I was like, oh, and you just start thinking all these memories start coming back.

And I was like, this is actually a really hard problem.

You're in grade five.

Like, this is pretty difficult.

I don't remember grade five being this difficult.

Well, so what can you tell what you did?

Tell us if you don't mind.

I posted it on Twitter.

I even tagged you, I think in the end of it, because I was like, you're going to be my best friend.

Oh, good. I missed it.

I think I saw it. Did I respond?

Oh, no. It was sort of.

So the question I posed.

So my kids are both pretty decent in math.

They're way beyond me already.

And it was like, you're standing on this 40 -meter building, which is 20 meters away from a tree.

And at a 45 -degree angle, you see like the height of the tree, I think was like 15 meters or something like how tall is the tree?

I see. I was like, oh, my God.

I might have to take that, but I was like, holy cow.

Grade five. I thought I was doing like multiplication and division.

What the heck is going on here?

Uh -huh. But the whole point of that was basically you have two daughters.

Yes. How should parents engage their kids in math, like rather than give them the answer or how do we get kids excited and how do we find that in ourselves again as we're helping our kids?

Yeah, because I think the parents are critical to this in that a parent who says, well, I never used math in my life, so it doesn't matter.

That's not going to help.

You know, we have to try not to pass on our own anxieties to our kids.

What I try to do and what I would recommend other people do is to not be afraid to admit that you don't know something.

That's a big, strong reaction to say, I don't know.

Let's figure it out.

Either we can figure it out by thinking about it or we can look it up on the web.

I mean, that's maybe a second best choice, but sometimes that's the best you can do.

But the key being, it's okay to not know everything.

Now, some—I suppose in some models of parenting, the parent is the authority figure and to relinquish authority is a big concession.

So, these are maybe in more traditional homes, the parent will never do that.

You're not supposed to be the equal or even the lesser of your kid.

But in intellectual matters, I happen to like honesty.

And if you don't know something, why are you trying to pretend?

You're going to get found out anyway.

Right. You know, and if you don't, it's going to be ugly.

There's a scene I'm trying to remember.

Yeah, it's in my left foot.

Do you remember this Daniel Day Lewis movie?

He's the—what was the name of the guy?

He was a poet, Paddy?

No, what was his name?

I'm not remembering, but you know the movie, I mean, right?

He's completely paralyzed except that he can move his left foot, the young boy.

And he later goes on—it's a true story—goes on to be a magnificent artist who draws fantastic drawings and does paintings with the toes of his left foot.

But early in the movie, we see him with his father and he's thought at that time to be mentally challenged, the young Paddy, because he has trouble talking.

A question comes up, his older sister is working on her homework and her father is there sort of reading a newspaper or whatever, and the daughter says, what's 25 percent of a quarter?

And the father says, that's a stupid question.

You can't take—25 percent is a quarter.

You can't take a quarter of a quarter.

And then young Paddy, in a very dramatic scene, starts making noises over in the corner of the room.

Nobody's been paying attention to him the whole time.

And someone says he's trying to say something.

What are you saying?

Go, Paddy. What are you trying to say?

And they put a piece of chalk between his big toe on his left foot and his, you know, pointer toe, and he starts scratching out something on this chalkboard.

And you can tell, as you're watching, he's trying to do one -sixteenth.

Because one quarter times one quarter is one -sixteenth.

He has figured out 25 percent of a quarter is a sixteenth.

But it's pretty hard to draw the one and the slash and the sixteen with his foot.

And it's sort of a sad scene because you can find it on YouTube.

The father says, ah, he's an idiot, you know, just ignore him because they can't figure out what he's drawing.

But he's giving the right answer.

Anyway, the point being that this father, who didn't know how to do the problem, could have stifled all discussion in the family, except that Paddy broke through.

So I looked this up.

I looked up the question my grade five came home with, and it's a telescope is set up on the roof of an office building so that the lens is 50 meters above the street.

OK. A scientist notices that when he looks out the telescope at a 45 degree angle to the horizon, he sees the top of a nearby tree that is along the same street.

On his walk to work, the scientist measures that the foot of the tree is 10 meters along the street from the entrance of the building.

What is the height of the tree, assuming that the tree has grown straight up?

Wow. All right. I'm drawing a little picture here.

Fifty tall. It's not obvious.

The, you know, momentary of panic.

I was like, I don't know, but we can figure this out.

I'm sure. And we ended up doing a lot of YouTube and figured out, I think how to solve it.

But wow. But you could easily just be like, I don't know.

And then you leave this grade five to sort of like figure this out on his own, which probably is not an optimal strategy.

But did you ever come up with the answer?

I think I have an answer.

How did you do it? I'll tell you if mine's right.

Well, I don't know.

I may be misunderstanding the question, but I've drawn a picture with something that's a line standing up that's 50 units tall, 50 meters tall.

Now, when you said 45 degrees viewed from the top of the building to the horizon, it wasn't clear to me if that means 45 degrees downward.

No. 45 up, sorry. 45 upward from the horizon?

That's one heck of a tall tree.

Okay. So let's see.

All right. So 45 going up, that wasn't what I had drawn.

But so if I do that, that 45 degree angle makes an interesting, if I go over to where the tree is and then continue up vertically from the top of the tree.

Let's see. Or no, sorry, the tree is very tall.

Like I guess I'm hitting the trunk of the tree.

It looks to me like I have to go 50 plus 10.

I mean, well, is that wrong?

50, jeez, I'm going to embarrass myself here, the professional mathematician.

But it looks like it's a 50 foot tall building.

And then because you said 45 degrees, that's going to make a half of a square.

Right. That's a 45, 45, 90 triangle, so to speak.

That's a half of a square, a right isosceles triangle, in other words.

So it was 10 units over east or west to the tree.

10 units north would be to the top of the tree.

So it looks to me like 10 plus 50, I would have thought 60.

Yeah, I guess we probably didn't do it right.

What we did was I may be doing it wrong right now.

No, no, I don't. You're doing it wrong.

We drew a triangle basically from the top of the building.

And all we had to do was calculate the height of the angle opposite the 45 degrees from the tangent, I think.

Oh, I think so. How do you figure that it was like a reduce a calculation.

So it wasn't exactly.

You could use the tangent, but it's but with a 45, a right triangle that has a 45 degree angle as one of its angles, the other angle is also 45 degrees.

Right. Because 45 plus 45 plus 90 makes 180.

Yep. So that's what I mean by saying it's a half of a square.

It's a square sliced along its diagonal.

That's a 45, 45, 90 triangle.

Okay, yeah. So it's like it's like you're stacking a square on top of the whole picture.

And so the fact is that when it's a square, the ten units on the bottom translates into a ten units on the vertical side.

That makes so much more sense.

OK, I'm going to have to go back.

But that's what you would have gotten from your tangent.

Your tangent of 45 would give you one.

So that so you would have concluded it's ten units up on top of the 50 that were there to begin with.

So yeah, I think 60.

But OK, well, this is look, it's not usually good to do to do math over a podcast.

What are what are the other things that parents can do to help their kids with math?

And by help, I mean encourage curiosity.

And for you, it's probably fairly natural with your daughters.

But for many of us, people have the same reaction I probably do.

And my kids come home.

I'm like, oh no, today's homework day.

What sort of like YouTube videos am I going to have to look up when he goes to so that I can answer questions in the morning.

Well, one thing I suppose a parent could directly try to help him or herself first.

Yeah, the parent if the parent started to like math and felt more secure, that would be a big help.

So when I wrote back in 20.

I guess was 2010. I think that's when it was 2010.

I was asked by the op ed page editor of the New York Times to write a series about math for for that kind of reader, for just the educated sort of person who's curious about wide range of things, who would be reading the Times.

And so that was the proposition.

Do 15 weeks of math in The New York Times starting from preschool, you know, like the idea of numbers up to as far as you can go to graduate school or beyond and make it understandable, make it fun.

And so it was a fantastic challenge.

I really enjoyed that.

That later grew into the book The Joy of X.

But it was always written with the parents in mind.

It was meant for adults.

And so there's a lot of references to things that only adults would know about literature or philosophy or sports or history or whatever.

And yet I find that these columns tend to get used a lot in schools because they do cover the standard curriculum all the way through grad school.

But but especially a lot of elementary school and middle school and high school anyway.

So I think, you know, parents could try reading those columns.

They're they're free if you have the Times subscription or you can get the first 10 of them free or you could also there's so many things on YouTube.

Now you mentioned YouTube and there are a lot of good resources.

There's there are just excellent.

It's like a golden era of math communication.

There's someone named 3Blue1Brown.

At least that's his handle on YouTube who makes really great videos about everything.

Just at a more pedestrian level, there's Khan Academy where you can learn all kinds of things.

He's very good. It's like his vision is bringing education to the world at no cost.

And to a large extent, I think he sort of succeeds.

He's really very good.

But there are others.

A person named Mathologer.

It's interesting because now the best teachers have unlimited reach.

They do. Right. The Internet has enabled that.

Look, before it used to be that you would get, you know, if you're lucky, you would get the best math teacher in your community.

And now you can you can access by and large the best math teachers in the world.

Yep. That's how it's done.

And that's the kids are already doing it.

So I had occasion recently to meet a seven year old boy whose mother said he was very excited.

She's actually a professor at my school at Cornell.

And the mother said that her son, who is seven, you know, that he was very excited to find out that a mathematician whose books he reads for fun actually teaches at the same school as his mom.

Could he could he come meet me?

So I was talking to this little boy and there's actually a clip of that my encounter with him because I didn't know anything about him.

I just thought I was going to shake his hand and you know who knows what a sign a book for him or something.

But he's no he's got all kinds of math he wants to show me.

And so I thought this could be fun.

So I told his mother take a little video of us, turn your phone on and just let's see.

Maybe he'll want to watch this video afterward.

Anyway she records it and we're talking for about 40 minutes where it begins with the boy whose name is Zamir.

Zamir shows me. First I don't know what is he trying to do.

He's just telling me to do some games on the calculator.

Then I realize he's making a thing called a magic square.

So just to remind people if they've ever heard of a magic square played with one.

This is a three by three square of numbers.

A traditional magic square you put in the numbers one two three up to nine such that every row adds up to 15 and every column adds up to 15 and every diagonal adds up to 15.

There's a way of putting those nine numbers one through nine in the you know arrange them into squares that every row every column and every diagonal adds up to 15.

That's an ancient idea.

That's a magic square.

What this boy Zamir had figured out how to do was something similar except that every row column and diagonal multiplied to the same number rather than added.

If you multiplied the three numbers you'd always get the same number.

So he's explaining to me how he figured this out.

And I thought this is pretty good.

This kid is seven. This is amazing.

But then he says to me after about like 10 minutes it also works with natural logarithms.

So and this is all captured on tape.

You know you could see it on YouTube me and Zamir talking.

And you'll see my eyes pop out of my head because I think wait a second.

What is this? This kid knows natural logarithms at seven and pretty soon he says yeah and it works with imaginary numbers too.

And you know. That's incredible.

But so we got onto this because you were asking what can parents do.

Zamir had already I guess the thing was that Zamir and other little kids are very aware of what's out there in the world of the Internet.

And so he knew me from the Internet.

He knew other mathematicians from the Internet and he doesn't really particularly read books.

He watches videos. That's where a lot of learning is happening for kids today.

So I would say parents should try to learn.

I mean sure they could help the kids with the homework.

But but there's a lot of good learning to be had on the Internet that seems to connect very well with this generation.

So I would I would try to use that skillfully.

It's not that hard if it says so to speak gifted child or someone with a lot of talent that poses a different set of questions than the kid who's very frustrated and hates math or is demoralized or even feeling shattered about it because it can be super you know soul crushing.

It can also just be boring.

I mean there's all kinds of different negative reactions.

Some people feel ego deflation.

They really feel like they're stupid.

You know other people can do math but they just don't see any point to it.

They think it's boring.

And and then there are yet others who find it very exciting.

And you know so there's challenges for parents of all three types of kids the bored child the the depressed or you know distraught child who has tremendous math anxiety and then the kid who's wants to do more math but is limited by the environment.

So I don't know I would have different ideas I guess for each one.

That makes sense. Tailoring kids switching gears a little bit.

Talking about your recent book.

What is calculus calculus is one of the greatest ideas of all time.

I would say it ranks right up there with relativity theory from Einstein with quantum theory of the atom you know with evolution from Darwin and and I mean it's just had an enormous impact on the history of the world.

It's it's the mathematics of change.

If you had to say it in one word that's what calculus is about how to quantify things that change especially things that change in ever changing ways.

So it's it's the first part of math that can cope with the dynamics of the world.

And you know what do I mean.

So the simplest kind of change is something moving literally moving moving changing its location from place to place.

So you could throw a ball or you could you know hurl a javelin.

You could be thinking about the planets moving around the sun.

You could be thinking about the concentration of virus in the bloodstream of a person with HIV.

You know after they take a combination drug therapy their viral concentration will plummet.

Thankfully and so when doctors develop strategies for that the life saving treatment nowadays the triple combination therapy that has turned HIV into a chronic illness from what used to be a near certain death sentence calculus played a big part in quantifying the dynamics of how the immune system interacts

with the virus and what role the different drugs you know that have been offered would play in all that.

So that's it. I mean calculus is the math for describing the world in flux.

And since everything is in flux you could see that it's bound to be pretty useful to have the ability to do that.

Can you tell us this story of how calculate or math I guess in this case and calculus influenced our treatment options for HIV.

Well OK. Yeah. So take your mind back to I'd say you know like the mid 1980s where in the West here in the U .S.

or Canada the HIV epidemic was really starting to hit.

It was just very mysterious disease wasn't so clear what was causing it.

And but the symptoms were very predictable that a person who got infected would at first show flu like symptoms they'd feel kind of sick for two weeks but then they get better.

You know they might have a fever.

They'd have you could see their T cells the most important components of their immune system had a measurable change could detect some virus in the blood but but they'd get over it.

You know. And so after two weeks it seems like the person was sort of better and then years could go by without any particular symptoms except for this strange low level of T cells these crucial components in the immune system.

It seemed to be that the T cells were being depleted somehow by the by the presence of the virus but otherwise people weren't that that sick.

But then after maybe 10 years suddenly a tremendous crash would seem to happen and they would become terribly sick and that's when HIV would become AIDS at which point all kinds of nasty opportunistic infections would set in weird kinds of pneumonia that you wouldn't normally see weird cancers that were very

uncommon. And then you know at that point the person would only have a very short time to live maybe a year or two.

So that the mystery I mean what was thought to hold a clue to what might be going on was this bizarre asymptomatic period of 10 years.

What's going on in the body for those 10 years when the person has HIV but they don't seem very sick.

Is it the case for instance that that HIV is hibernating during those 10 years that it's just somehow lying dormant in the body waiting to come out and become full blown AIDS.

If you believe that's the picture and certainly some viruses do that you know people who have been infected with different types of herpes viruses let's say we'll know that they can have long periods with no symptoms in between outbreaks.

So we do know and chickenpox is a similar thing.

Where people don't get shingles until they're much older after they had chickenpox as a little kid.

So you can have tremendously long dormant periods of viruses not doing anything in the body.

So if you think that's what's happening with HIV then that would mean if you had any drugs to treat it you shouldn't use them at the beginning when a person is infected.

You should wait until the symptoms start showing after 10 years because you don't want the person to develop resistance to the few available drugs this being back in 1985 or so.

So that was the way HIV used to be treated that they really wouldn't do much until full blown AIDS and then it turned out that available drugs didn't help.

But all of this changed around 1994 when a new wonder drug called protease inhibitor became available.

And the trouble even though with that is that just one drug people would always develop resistance to any drug you gave them and HIV would come back.

So so where math comes into the story is that in the mid 90s Dr.

David Ho an AIDS researcher and a mathematician Alan Paralson worked together with a team of other researchers to figure out what these protease inhibitors were actually doing with HIV.

How are they working.

And they showed that after taking one one of these drugs that the levels of virus in the blood would drop exponentially fast.

It would really plummet.

And what was so important about that is that by making measurements on the rate of this exponential drop Paralson and Ho were able to show that the body was producing about a billion virus particles every day.

HIV was making an enormous amount of new virus and the immune system was clearing it out and flushing it out of the body just as fast as it was being made.

So it was a completely different picture that was not the case that the virus was dormant those 10 years.

In fact it was in this all out fury.

Just a bottle of attrition basically with your body.

Yes exactly. It was a furious battle of attrition an all out war that was that was being held to a standstill.

The immune system was holding HIV at bay until it gets exhausted.

And that's it. The math also showed that given this furious replication rate of HIV it was no wonder that it was able to become resistant to essentially any drug.

Mutations were happening so fast when HIV would get copied because it gets copied inaccurately.

I mean it's an RNA virus with a bad copying mechanism.

That's actually to its advantage because it can generate many variants that can escape any drug you try to hit it with.

But what Peralson's math showed is that if you did two drugs your odds were a little better because then the virus would have to do two simultaneous mutations.

The odds of that were lower than one but three drugs would be the sweet spot where the odds were so low that HIV could mutate three simultaneous ways that you could not you could basically keep it at bay for a long time.

And that's now the modern regimen.

The three drug therapy.

So math was key in understanding that.

It didn't certainly didn't solve the problem on its own.

You needed the immunologists and the doctors too and of course the pharmaceutical companies.

But but with all of them working together calculus was a key supporting player in in helping change the way we look at HIV and certainly how we treat it.

And our effectiveness at that.

And it also played a role in GPS.

Can you explain that?

Or does it's the fundamental role in GPS I think.

Well that's right. Sure.

Anytime we use our GPS gadgets to find our way to a strange destination or sometimes even to find our way home when we're lost after going far away.

GPS is a wonder of calculus.

It's got so many different aspects of calculus built into it in the way that it acquires signals from the satellites overhead.

The way that the satellites and the whole system estimates distances by doing a complicated mathematical calculation.

You know it has to look at distances to three or four different satellites overhead.

There's also really what the GPS system does is it doesn't directly measure distances.

It measures time and converts those into distances.

So the time is the time it takes for a signal to go from the satellite to your GPS receiver.

Given that it's traveling at the speed of light because it's an electromagnetic wave this signal it's going to move at the speed of light.

And so by you have to time very precisely how long it takes for the signal to get to your receiver from the time it was emitted by the satellite overhead.

Now what's really tricky about all that is that the satellites need to keep extremely accurate time.

They have onboard atomic clocks in them.

The most accurate time pieces we know of that are based on principles of quantum theory which itself is built on calculus as its math its infrastructure.

But more than that when the when the satellites are moving so fast overhead they're actually going fast enough that Einstein's theory of relativity applies to them in a significant way and they the clocks on board those moving satellites run at a different rate from the clocks on the ground.

In other words time changes time doesn't move at the same rate.

It sounds unbelievable.

I mean Einstein thought of this idea about more than a little more than 100 years ago.

Time actually changes if you're moving.

It can speed up or slow down.

Can you explain that for me.

Well God it's not it's not an easy thing to explain.

I mean we'd really have to go into a bit of relativity theory but it is a consequence of relativity that time can change intuitively.

In other words it can actually slow down when you're moving fast.

It can also speed up when you're in a weaker gravitational field.

So when these satellites because they're farther from the center of the earth are in a weaker gravitational field slightly than we are on the ground.

So these are minuscule effects.

We're never aware of them in our ordinary life.

But these GPS satellites are so accurate in their atomic clock timekeeping that they can actually and they do all the time effectively confirm Einstein's relativity predictions to this.

In this sense if we didn't build in the Einstein in corrections to timekeeping the whole GPS system would fall apart in about 20 minutes.

It would it wouldn't be able to keep accurate time.

So OK it's a big long walk.

I've just taken here to give it to you but I mean there's a lot more to this but but suffice it to say the GPS has has a lot of calculus and advanced physics built into it.

And we don't give it a thought.

You know we're just trying to get home at night.

Let's see if I understood this correctly.

So I put my phone into my car turn on Apple CarPlay get directions.

It's triangulating between three or four different satellites and the time that the satellites sync up their atomic clocks and then it's triangulating between how long it gets from each of those satellites to my phone.

And then based on that it can triangulate where I am.

Did I. Yup you've got it perfectly because those those clocks on those satellites are very accurately maintained and the military keeps extremely care careful measurements of where the satellites are.

So they have to know exactly where those satellites are and also you know what time it is on board the satellites.

And so as you say you know they're all at somewhat different distances from your car from your receiver.

And so yes you get to measure as you say triangulate you get to measure several distances three or four distances to all those different satellites and knowing those four distances knowing where those satellites are that places you uniquely on the earth.

Not only that it also places your velocity.

I mean so GPS can tell you how fast you're moving as well as where you are in three dimensions.

How does it tell you how fast you're moving just based on where you were and where you are.

Okay that's right. So we can measure your position a nanosecond later or whatever a small unit of time later and all those four distances have changed slightly.

So it's that's of course one of the key ideas of calculus figuring out a rate of change what we call a derivative.

That's an example that the rate of change of your position when a short time interval lapses that's a quintessential calculus calculation.

What are the other terms that we would use around rates of change.

Well in economics people are always using the word marginal so if they say the marginal utility you know how much extra pleasure or utility do you get from something for the next dollar that you spend or what's your marginal return on an investment you invest one more dollar how much bang do you get

for that buck. So those are rates of change the rate of change of return with respect to investment.

That would be an example and that's a common sense thing you know you don't want to at some point the marginal returns start going down.

So it's not worth it to put in that extra dollar of investment.

So we use that idea a lot there but certainly in physics we talk about speed that's a rate of change of position with respect to time.

We have acceleration.

That's the rate of change of velocity.

But even something as simple as a paycheck you know when I say I'm making six dollars an hour let's not say that.

That talk about minimum wage.

Let's say we're making OK.

Fifteen dollars an hour is what they're talking about now.

Everyone should be able to make that.

If you know if you had a decent wage that's still a rate of change right.

It's dollars per hour.

Anything where you say per is a rate.

Exchange rates you know how many marks per right per dollar or how many pounds per dollar.

Those are rates. You mentioned economics.

I'm curious as to why physics math is so accurate and economics math is so wildly inaccurate.

Is that because the math the mathematical models don't apply as well or I mean to what extent is biology give us a better model for economics and physics.

Lots of great ideas in that question.

Well OK. The short answer would be that physics is a lot simpler than economics.

You know when you when you measure the moon it doesn't mind it doesn't react.

You know it's just an inanimate thing.

The laws governing inanimate bodies are just a lot simpler and more easily quantified than the laws governing populations or individual people.

So the task of the social sciences is extremely hard.

They get to feed back on the system that's measuring them.

It's also their ethical issues.

You can't do experiments as easily or sometimes you can't do them at all on people or on populations of people.

It's much harder to do controlled experiments.

You try to pin down some variables and they just pop up somewhere else.

So if you think about the history of science which sciences were solved first or where did we make progress.

The first science to really make good progress was astronomy which I always think is kind of surprising at first given that the moon and the stars and the planets are very far from us.

They're very remote and you might think like why shouldn't biology be the subject where we make the most progress.

It's very important medicine and helping sick people and prolonging life and all that.

You would have thought we devote so much attention to that but it's not we didn't you know we had witch doctor medicine for most of history and even to this day there's still a lot of black art in medicine.

And it's because it's intrinsically complex where astronomy if you think about it has a lot going for it.

The motions of the planets are very repetitive and regular.

They the moon is very predictable.

It's also very slow.

It doesn't change that much from night to night and it's very observable.

You can just look up there and see what's going on and make measurements pretty decent ones.

So it's it's at a time scale where it's not too fast or too slow for naked eye observation whereas the processes in the body are are so fast sometimes in the molecules or the cells involved are so small that biology is just intrinsically really hard and economics and sociology and psychology are even

harder still. Do you think biology is necessarily valuable then or is it a matter of like we don't.

Once we understand more we'll be able to measure and predict with the degree of accuracy that sort of like rivals physics or is it something that is just it's inherently too complex and no amount of computing power is going to be able to solve it because it's a dynamic system.

Well I think it's closer to the second though I wouldn't be as fatalistic about it as that.

We have made a lot of progress in understanding all kinds of things about say.

Arrhythmia is in the heart which are ultimately electrical problems of you know aberrant waves propagating in the heart electrically that shouldn't be that are making muscles in the heart contract at the wrong times so that heart so the blood doesn't flow effectively.

You know so there are some parts of biology where it's really almost like mechanics the heart as a pump.

But there are other parts of biology.

Say you know emotions in the brain and mental illness things like this are still very very problematic or so you know that's in a way it's a good thing.

We have a lot of work to do that will keep us busy for generations to come but I think it's just in the nature of biology that it's much harder as you say it's very complex there are lots of parts also keep in mind that there's enormous diversity in biology that.

My genes are different than yours even though we're both human beings there's right our molecules are the same.

But we're configured differently whereas in the left and physics it's not like that any two electrons anywhere in the universe are absolutely indistinguishable.

There is no diversity of subatomic particles I mean they're different particles electrons are different from protons but every electron is completely the same in every respect as every other electron same charge.

Same mass they never break they never age they never chip you know I mean so in that way physics is really simple whereas hemoglobin molecules you know could all be a little bit different.

There's also a lot of noise in biology a lot of randomness that's just because of molecular jiggling more.

It's just inherently chaotic yeah so it's it's really hard and it's going to keep us occupied for a while but still it is ultimately chemistry and physics.

I mean there's no I don't believe in any vital spirit or soul or anything like that I'm sure some people do but I don't I mean to me it's all material it's going to ultimately be understood.

In purely materialistic meaning I'm not talking about money obviously I mean I don't think there's anything there but atoms and subatomic particles configured in increasingly subtle ways.

And correct me if I'm wrong you're you're more interested just intellectually and sort of the orderly side of nature than the chaotic side correct.

I would say that's true yeah my my interest has always been in how does order emerge from chaos so I do find chaos interesting as a starting point but.

Whereas some people revel in the chaos I I like self organization I like systems that spontaneously show astonishing feats of collective behavior where they somehow get their act together on their own with no no commander no outside force telling them how to behave because I think that's you know we

see that all around us we see.

I assume life evolved spontaneously you know in the consistent with this position I'm giving that it's all materialism I think that's one of the great mysteries how do you get life from non life without a creator.

You know how it must somehow be in my world view that the laws of nature in the right conditions will lead to life emerging from chemistry but understanding the origin of life is one of our great scientific mysteries people are working on it's not hopeless but it's we don't have the answer just yet.

What is morality come into self organizing.

Yeah morality well.

Good thorny question there you know a traditional view would be I suppose that cultures and religious traditions and our parents give us they help us learn right from wrong and morality is something that's passed along through culture but.

From a different point of view it might be an outgrowth of biology.

What do you mean okay yeah well.

So I'm thinking of.

Series of experiments that were done if you could call them experiments that were were computer tournaments run by a political scientist named Robert Axelrod out of University of Michigan.

So Axelrod is is one of the great political scientists of our time and he asked experts in many different domains economics psychology game theory math physics computer science to come together and play actually to submit computer programs to play this famous game called the prisoners dilemma.

I suspect your money your listeners will know the prisoners dilemma but I'll just remind people I mean the prisoner's dilemma is a model for thinking about lots of situations that occur in real life where.

You and someone else have basically two decisions are you going to play nicely with each other and are you going to sort of cooperate the scenario that is always talked about is you and your friend are both being held by the police.

Accused of having committed a crime okay so that the name comes from his 1950s era scenario of of the two guys are being questioned separately by the police.

And they're you know each in their own room and the police say look we've got lots of evidence on both of you guys, we know you committed that burglary together.

If you will just confess will go easy on you and go hard on your partner will put him away for a long time and you know you'll get off easy but you just got to let's go you have to confess.

And of course they're saying the same thing to the other guy and the question is, are you going to rat out your friend which is considered not cooperating so the word is used in a strange way in game theory you're cooperating with the police but you're not cooperating with your friend by being a rat.

And it's it's relative to your friend that we're talking about so so that's the question does like it's in each player's interest I'll think of these as players playing a game now it's in each prisoner's interest.

To rat out his friend, but if both of them rat out each other, then the police have a very easy case and it's bad for both guys they'll end up going away for a pretty long time.

In this in the normal set up the person who doesn't cooperate if one rats out the other and one keeps quiet the guy who kept quiet goes away for a very long time so that's the worst outcome is to be a sucker where you keep quiet and your friend you know cheats on you.

So anyway the point being that that this prisoner's dilemma is this interesting complicated scenario where it's in everyone's narrow self interest to be mean and not cooperate to defect.

To defect is the jargon exactly to defect as the jargon used in the field if you defect on your co player your partner.

But that assumes like a one iteration game right.

Yeah that's right so in the in the thinking where we're only going to play once and I'll never see you again then it's always in you know it's presented as a rational thing to just be a tough guy and defect on your partner.

And both players think that way and why it's considered a dilemma is that if we would both just cooperate with each other it would be good for both of us right but the problem is if if we both have this mindset.

It's it's always tempting you know to then say well maybe just this one time i'll take advantage because there's so much reward to be had by doing that so.

Anyway so so the back to Axelrod he set up I mean it's been a real paradox like how to play prisoner's dilemma if you imagine playing the game repeatedly if i'm going to see you again and again.

Maybe then there's more chance for cooperation to evolve between us because, although in the short term I might benefit from screwing you you could always screw me back and.

You know, maybe if we just sort of develop trust this could be good for both of us over the long haul so why we're talking about this, as you asked me earlier about morality and.

I found Axelrod's experiments very illuminating in this respect that what he found when he ran these tournaments of all these programs playing against each other.

He found that the programs that tended to do well in the tournament had four properties in common and he summarized these four properties.

By saying that first they were nice which he defined as meaning they never were the first one to defect if they were playing another program they would always begin by cooperating on the first move.

And then, if the other program cooperated back they would continue to cooperate because they were nice programs they would never defect first so they could set up these long strings of cooperation with other players and both do really well.

So being nice was principle number one that actually works well in an environment where there's a lot of players of equal strength equal power.

Playing against you in this vicious prisoner's dilemma game and what's so interesting is nobody's being nice for moral reasons they're these are egoists okay these are classic Adam Smith self interested.

I'm doing what's good for me players they're not trying to be nice they're not altruists for any moral reason they're just trying to do what's good for them.

But it turns out being nice is good for them if they're in an environment where there's a lot of other players equally strong you know who can inflict as much harm on them as they can on the other player right so that's that's principle one be nice.

Principle two that was found out you know I'm not talking again here about any kind of moral philosophy this is just what worked in the tournament be nice but be forgiving.

If the other player cheats on you sometimes well don't just retaliate forever you got to let bygones be bygones after a while so it's good to be nice and forgiving but it's also not good to be a patsy you should be retaliatory you have to inflict punishment.

If someone has abused you for no reason that is you they gave an unprovoked defection on you then you have to hit back so be nice be forgiving be retaliatory and finally be clear.

The programs which were too confusing and too subtle and too brainiac like there were some programs that tried to make a statistical model of what the opponent was doing.

Right but then they become unpredictable I would imagine in some sense.

That's right they're so inscrutable they're so unpredictable that you don't know what they're going to do and it's almost like you're playing a menu each time you play so you might as well defect on them.

Because you don't know you can't figure them out you can't build up a relationship so be nice and clear forgiving and retaliatory and that's what emerges as a way to thrive in this environment and what's so interesting about that.

Is that this is a culture that has evolved around the world many times this is eye for an eye and a tooth for a tooth this is this is Old Testament morality.

And computers discovered it on their own this is not was not programmed into them this is just what worked.

So it becomes our system because of biology and how we evolution basically it's natural selection in a sense people who employ that strategy are more likely to.

Spread their genes.

Well that's so yeah okay I mean the argument would be if you play this kind of style.

Axelrod actually did do an evolutionary version of the tournament where where programs that did well got to reproduce more copies of themselves right.

So just like you described and so then he looked over many generations what how did the population evolve and he found that it sort of evolved toward players that played this style called tit for tat.

Which is they always they always cooperated on the first move they're really simple programs in fact it was the shortest computer program submitted only four lines of code.

On the first move cooperate and on every subsequent move do whatever the opponent did on the previous move you just give it back to them if they cooperate you cooperate.

And that's what we know of as as tit for tat.

Yeah that's the tit for tat now but the story is more complicated like everything in life because although Axelrod did find that tit for tat worked well in his tournaments.

It's not some kind of universal best way to behave it turns out it's a little too ungenerous it's a little bit stern in and what's really here's the weakness of tit for tat sometimes people make mistakes.

Yeah and not because they're mean or I mean just mistakes happen sometimes you are trying to be nice and a person interprets it as an insult.

Now if that person is following a tit for tat morality and so are you then when this accidental defection happens they'll say well now I OK you know I got to give it back to you so then they'll defect but now you being a tit for tat player have to defect on them.

Now you're in this vendetta that it's very hard to get out of.

I have a friend who his approach to this is forgive unless it's malicious.

Yeah yeah good. Well yeah I mean there's a there's a computerized version of it which is tit for two tats right.

You know or some number of tats and so there are generous tit for tats.

Yeah anyway it's a it's an ongoing story in game theory this is a branch of game theory that people call evolutionary game theory but just to not get too lost in the weeds the point was it starts to give the contours of a story in which morality can evolve right from self interested individuals playing

against each other.

Now is that really what happens in evolution that's that remains to be seen there are some examples of it in evolution you know like when.

Animals that hunt say picture I don't know lions the female lions out on a hunt it can be dangerous to try to go after a big scary wildebeest and they can kick you or hurt you you know when you're trying to kill them.

So maybe it's better to let the other lions get a little ahead of me and I'll just kind of bring up the rear you know you could be a free rider and it's tempting that is all the lions are kind of playing a type of prisoners dilemma with each other where it's tempting to cheat.

On your on the rest of the what would it be called a herd no that's not what it's called what is it with the lions pride a pride.

Okay but anyway so there are instances in biology where something like a prisoner's dilemma is happening but yeah anyway so I don't know how much it really tells us about morality but it's an interesting story it may tell us something.

Well let's talk a little bit about decision making in terms of mathematics is a hyper competitive world I would imagine you're you're an adviser to students you're part of.

There's publishing papers there's sort of like credit and attribution how do you think about this with your grad students how do you advise them how do you help them make decisions how do you what models did they use to make decisions.

Mm hmm it's something that we think about a lot because really the first issue for a student is what to work on it.

Getting a PhD is all about discovering something new staking a claim in in the intellectual firmament in the mathematical landscape you know you have to come up with something new and interesting.

That is yours you have to innovate and where do you find a good idea because there's everyone's trying to do the same thing and these are also smart ambitious people to.

So one of the things that comes up a lot is that the first few ideas that you'll try.

They might seem promising but then at some point the going gets rough it's hard to make progress maybe you don't have the technical tools to solve the problem even though you're fascinated by it or.

For whatever reason is not turning out as interesting as you originally hoped.

And then there becomes I know sometimes on your show you like to talk about like sunk cost and other fallacies you know we've spent a here's a student has spent a lot of effort on something.

Yeah they've put in the cost right should they keep banging their head on that same problem or is it now time to give up like you know when is it time to quit.

Yeah talk to me about that well it's a very hard decision because you've spent a lot of effort you've grown attached to a certain question.

If you quit on it you may feel like well that was all a waste but on the other hand if you keep banging your head.

And not making progress than you're there's an opportunity cost you could have been thinking about something else and maybe you would have made progress on that new thing.

So it's and and since you don't know how it's going to turn out because this is an issue of genuine discovery and uncertainty it's not clear what to do this contrast also come into it to like contrast.

Yeah are you trying to think of oh there's other students working on this but they might not be as clever as I am so are you trying to like also ascertain what is the thing that I like doing that other people are not doing or.

I'm thinking about this a sense of you know if you take somebody who is really intelligent and you apply yourself to maybe not the hardest problem but the second hardest problem you might have a better chance of ascertaining your PhD does that make sense.

Totally makes sense right so problem selection is such an art form you know that you sometimes it's better to go as you say after the second hardest problem so maybe the gold ring you know is premature we have to build up to it so.

There are people who try for the hardest thing and they never succeed because they're going for pie in the sky all the time.

There's also you sort of hinted at it the idea of comparative advantage what is it that I bring or my student brings that might give us an edge that that other people don't have or you know so they're all these different things to think about.

The kinds of edge that we tend to have we I mean really live I guess me and my students is that we're very widely interested in many things.

Some mathematicians are narrow and deep deep is our highest compliment actually in math that person is deep that work is deep that theorem is deep that's what that's the standard of excellence but not really for me.

I mean whether it's just because I'm not capable of it I don't know but I kind of like shallow and broad maybe shallow is you know to to self deprecating but broad there's so much to be gained by thinking out of I don't want to say that cliche out of the box but you know out of the square.

Okay out of the square being interested in wacky things like humanities or philosophy or or sociology that has often really worked well for us how does that help you well because I see I see problems that other people don't realize their problems so an example would be okay so yeah let me give you a little

story so probably on paper and maybe in reality my most successful student is a guy named Duncan Watts.

Who was Australian from he was a physicist he was in their naval defense force he wanted to go to grad school to study chaos theory which was something I worked on a lot and so he became my grad student and the first few problems we worked on together.

It was just like this scenario I was describing earlier that he was getting stuck we weren't really making good progress one was something about the way that lymph flows in the vessels of the lymph system.

It makes certain oscillations we were interested in things that oscillate and go up and down and have cycles you know so as an expert in cycles I thought maybe we work on lymphatic oscillations.

That could be important but we couldn't make progress we kind of got stuck we didn't know enough about the lymph system so then we had to do what I think of as strategic quitting that we have to.

Decide it's time to cut our losses this is not going anywhere let's do something else so we did we stopped and we you know we quit what the thing your college or high school coach tells you don't be a quitter yes I say do be a quitter sometimes you have to quit when it's not panning out.

But then don't just give up you have to come up with something else so we kept thinking of things to do and finally in.

Well I want to say in desperation we started to work on a problem about crickets now crickets you know chirp crickets chirp they make a rhythmic chirping sound at night and in Ithaca New York here where I live or Cornell is we have a species of cricket called the snowy tree cricket that.

That they chorus in unison they all chirp together in these vast choruses so that they make this enormous sound at night in the in the fall or in the summer.

And that's a fantastic kind of synchronization where these are not very clever creatures, but they somehow can harmonize and all chirping unison and biologists have wondered how can they do that.

And it's partly interesting because the crickets are interesting but partly because a lot of things in biology synchronize like the cells in our heart that tell our heart went to be our pacemaker cells get in sync.

Brain cells get in sync when we're having epileptic seizures so we would like to understand how to stop that anyway so crickets are one instance of synchronization and we thought they might be a tractable one to do experiments on because they live right here in Ithaca and we could capture them and do

experiments on them.

And maybe figure out how they are able to synchronize in their chirping anyway so while Duncan was working on that he made this interesting creative leap his father had said something to him once.

This was back in the 1990s did you have you ever heard that you're only six handshakes from the President of the United States or from anyone else on earth and this idea of course everybody has heard of the six degrees of separation idea.

But Duncan put this together with what he was trying to think about with the crickets that they're out there in these orchards.

He wondered which cricket can hear which other cricket like are they all connected just maybe to the nearest ones to them or are they listening to the whole field or are they somehow connected in this network.

That's reminiscent of you know, like what if they're all just a few handshakes away from each other in terms of who hears who.

So he put these two things together this this thought from sociology about social networks and this is well before Facebook or anything else.

You know what is the basic mathematics of things that are that you could think of as networks where every node in the network is just a few hops or just a few handshakes away from every other node.

What would a network have to be like to have that property if it's really true that the planet earth the social network of the planet has this property.

And what would that tell us about how crickets can synchronize now other systems networked in this way could behave.

So I'm bringing this up because look at how weird this whole thing is we're talking about crickets or suddenly talking about six degrees of separation which comes from a movie and a play by that title.

Which originally came from a social psychology experiment you know nobody in the math department is thinking about that kind of crazy stuff this is.

I'm interested in pop culture I'm interested in science and so I think about weird things and sometimes there are really important and relatively easy problems just waiting for a mathematician to look on it.

Is that because you're applying sort of mental models from other disciplines to the one you're looking at.

So yeah it's different mental models knowing what questions arise in what fields what things have long been problematic like you know the sociologist will tell you the social network problem of six degrees of separation was solved in the 1960s they thought that problem was done.

And maybe from their point of view it was.

But from a mathematician's point of view it was certainly not done.

I mean it seemed to me we don't have the foggiest idea mathematically which networks would have this small world property.

I say small world because of the you know the old idea you meet someone on a plane and you start talking to them and you realize you know someone who knows someone you know who knows their cousin or something.

So this this phenomenon of it being a small world it's right under our noses yet it's not understood mathematically we don't really know why is it so small.

So there's a math problem there and and recognizing what is right under everybody's noses.

You know but seeing that something wonderful and it's saying something mysterious in it that's that's a kind of skill and that's the skill that I.

You know I'm very interested in trying to develop in my students and that I've been able to leverage in my own career over and over again.

When I come back to strategic quitting just for a second is there that sounds more like an art than a science.

There's a lot of things that come into it you know I mean you have to decide how frustrated you feel how much time you have left like for a grad student there's often real world questions do I.

Maybe I have a family I need to graduate I need to get a job so I get really paid properly.

In that case we better quit that much sooner and make sure your next problem is that much more tractable you know it's almost like with stocks and bonds and things there.

They're safe investments that don't return that much there's riskier investments that might return a lot but could also go belly up very easily so you have to think about.

similar issues right like what's your time horizon when do I need to get out of here how much payoff am I looking for how much am I willing to gamble.

So all those different things go into the thinking about what what question should I work on next.

Does anything else come to mind when you're asking that question of your students or yourself.

Yes a big thing is personality I mean in Duncan Watts case since I was just talking about him with the cricket problem that became the small world problem and maybe I should just say.

I mean it's gross it's kind of going to come off like bragging but just to finish that thought it's this paper is now among the hundred most highly cited papers of all time in any scientific discipline.

I mean it's the biggest home run I'll ever hit in my life for sure and long after I'm dead it's the one thing that Duncan and I will be remembered for this was a monumental.

game changing bit of work that started from you know from just a crazy question.

Yeah I love those solutions for you're pulling something from other disciplines and you're seeing something that nobody else sees even though it exists within the world.

Yeah as far as like what does it take to you know how do you decide about the quitting I knew something about Duncan's personality which was that before I had even really gotten to know him I had observed a picture of him on his office door.

Of him hanging by his fingertips literally on a cliff 100 meters above the sea in Australia a place called point perpendicular.

He's a rock climber and he's a little bit of a crazy person it's also physically very very impressive he looks like a green beret like someone that could kill you if he wanted to and.

He's the kind of guy who hangs off of off of precipices by his fingertips and does it for fun so it seemed to me like with that student we could work on something extremely risky and extremely exciting and he would not be afraid and he would find a way to make it work he wasn't the technically best

mathematician he still not.

There were other kids that were more math Olympiad caliber who could solve any textbook problem you gave them Duncan wasn't like that but he could muscle his way to a solution it wouldn't be elegant but he could get it done and he was fearless.

And so we worked in this area that I mean I had to tell him at the beginning look I know nothing about social networks that's going to use a part of math called graph theory which I'm not an expert in.

If we were talking about crickets and oscillations I know about that but I don't know about networks and actually nobody really knows so we're going to be way out of our comfort zone here we might embarrass ourselves and so we were very secretive about what we were doing we didn't tell people we worked

on it for maybe a year or two and.

You know we had nothing to show for it for that whole time but the hope was that it could be really big when it finally came out if we got lucky and it turned out we did to what extent does that raw skill matter in comparison to what other attributes do you see in students that make them successful.

Well raw skill certainly has its place you know if you don't have any skill and I'm talking like skill in the sense of technique like if you are a composer and you couldn't really play you know on the piano to hear what you're trying to compose you're going to have trouble and in math you have to have certain technical

skills and I'm sure in every discipline and computer science if you can't program with some facility there's only you know so much you can do.

But but skill is so much what we emphasize technique I guess I should call it technique is so much what we emphasize in school and it's just one part of the of the portfolio courage is a big part judgment.

You know these are hard they're intangible I don't even really know how to define a lot of these but a nose having good taste knowing what's going to be cool if it works.

Knowing what other people might find interesting like my dad my dad didn't go to college neither did my mother but my dad had a shoe store and he said to me it doesn't matter what shoes I want to buy you have to know what cells you know you have to know what the people want to buy and so it's sort of true

in research I mean it might sound a little mercenary to put it that way but we're sort of in the business of selling ideas I don't literally mean for money I mean our currency is a is a status and getting nice jobs and getting recognition and and also the thrill of discovery and all that but still a great discovery

that no one appreciates is not really a great discovery because science is a social enterprise it's not just enough to do the work you have to communicate it and help other people understand why it matters.

Reminds me of this this story where a guy goes into a tackle shop and looks at the lures and says to the fish eat these green do they go after these green lures and the guy working there says I'm not selling to the fish.

Well that's funny that's good I mean I wonder about that story what do you think I mean that's that's sort of a not really right is it because if that if the guy if the fish don't bite you're not going back to that store.

Well I think it sort of goes back to that organized morality in that this sort of one off are we playing a game or are we playing a one time game and it was interesting I was traveling with my kids this summer and we sort of went to this tourist trap and we ordered a bottle of water without even thinking

and it was eight euros.

And I was like oh well let's work through this problem and we're sitting there at the table like I was like just we just got you know.

We just learned something here like let's let's pay attention to it and try to get the kids to learn a little bit and I'm like.

Well what would the difference be if this restaurant was full of local people do you think that they would do that no OK so if it's full of tourists, how can they do that well because it probably will never be back.

And so you can get away with this not saying is right there's no sort of moral judgment on my part here or wrong but you can get away with it whereas if you were serving to an audience that is not a tourist place or a customer base you can't sort of get away with that type of behavior because you would go

to business because people just wouldn't come back.

But when your V place in town for this particular type of piece of cake that the town is known for you know everybody goes there and you order cake and then of course you get thirsty and you know the cake is cheap and the water is ridiculously expensive.

Not a good example of real world example of what we're talking about that there's one shot businesses and there's long term relationship kinds of businesses yeah and they and they will tend to evolve different strategies it's understandable.

What's really fascinating to me is like so often we.

We know we're in a long term relationship with somebody and we'll convince ourselves that will make it up to them if we take advantage of them right so if you think of four permutations of relationship there's win win win lose lose lose win but in.

If we map that to biology only one of those survives across time right which is the relationship has to be win win but I find a lot of people I'm going to take a little bit of advantage of you right now not too much but I'll make it up to you later and then we never sort of.

We always know what it feels like to be on the lose side of that relationship and it never sort of like happens that it sort of equalizes or gets made up or so even if you think you're playing a.

Multi iteration game we often make these trade offs I think in our head where it's like I'll make this up to you in the future and then we are inaccurate at that sort of score keeping if you will and.

I think that's so often how a lot of our relationships that work become after we leave work I mean I've noticed a trend with a lot of my.

A lot of people I know colleagues who retire and then they go from having sort of all of these friends to not really having many friends right so their friends came from their position or sort of at work anyway their friends came from their position.

In part because they had all these trade offs that they sort of realize later that they you know achieved success, maybe in a way that was mutually exclusive from relationships of meaning.

Uh -huh uh -huh. Very interesting there were there were actually you know in a primitive way computer programs that tried a similar thing in this Axelrod tournament after he announced to the community what the results of the first one were that it was at the time good to be nice and.

Forgiving and then you would think many players I mean it was much bigger tournament, the second time many more entrance and you would think a lot of them would submit tit for tat now that they learned how well it did.

They didn't though everybody thought they were cleverer than that and they would submit things that were.

They thought basically could do pretty well against tit for tat by occasionally taking advantage of it just rarely just like testing it.

You know or test the other program and then if there was too much retaliation they'd back off and go back to being nice and and it turned out.

That that little variant that kind of mutation if you will was a really deleterious mutation, because it led to exactly what you're talking about it would lead to a breakdown of trust that had been delicately established before then and it was very hard to get it back.

Yeah, especially in human systems right because you can appear to trust somebody but not actually trust them so yeah you can sort of trick them in a way that maybe the simulations in the computer can't do that's right, which is sort of.

Makes everything a little bit more complicated but also really more interesting from a sense of you should go positive and go first always and my friends principle of sort of forgiving unless it's malicious seems like a really good life strategy.

Uh huh uh huh yeah it is it sounds like this is a nice friend to have you know generally a sweet soul.

Yeah definitely listen see if this has been a fascinating conversation I've really enjoyed talking to you.

Thanks a lot chain it was a pleasure to be with you.

You can find show notes on this episode as well as every other episode at F S dot blog slash podcast if you find this episode valuable shared on social media and leave a review to support the podcast go to F S dot blog slash membership and join our learning community you'll get hand edited transcripts of all the podcasts and so much more.

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[수학적 사고와 탐구: 스티븐 스트로가츠와의 대화]-[#73 Steven Strogatz: Exploring Curiosities]

📋 Summary

수학적 사고와 탐구: 스티븐 스트로가츠가 전하는 삶의 지혜

1. 수학 교육의 재발견: ‘덮는 것’이 아닌 ‘발견하는 것’

2. 실패와 전략적 포기(Strategic Quitting)

3. 미적분학: 변화를 측정하는 언어

4. 진화 게임 이론과 도덕의 기원

결론: 지식의 공유와 소통

🎯Key Sentences

📝Key Phrases

📖 Transcript