Hirosi Ooguri: Could AI Find Physics We Can’t Understand?

SPEAKER_1 (0:01)

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Hirosi Ooguri (0:30)

I'm afraid there might be a situation where AI give us answer to fundamental question in theoretical physics, and we wouldn't be able to understand it, just like my dog would not have understood how a refrigerator works.

Curt Jaimungal (0:43)

This is the legendary Hirosi Ooguri, chair of Caltech's Division of Physics, Mathematics and Astronomy. He's a titan in the field of theoretical physics, and today we center around the final theory of physics.

Hirosi Ooguri (0:55)

If it is left for humans, it might take 2,250 years to verify the prediction of string theories. But AI may be able to solve it.

Curt Jaimungal (1:04)

On this channel, I, Curt Jaimungal, interview researchers regarding their theories of reality with rigor and technical depth. Today, I'm excited to bring you Hirosi Ooguri's first ever English podcast. And as mentioned, we focus on physics and AI, and a surprise hidden in his PhD thesis that he happened to just rediscover many decades later.

Hirosi Ooguri (1:24)

And there they were, right in front of my eyes, the numbers that I calculated in my PhD thesis. We're like, wow, there is a truth in the world and we can know about it.

Curt Jaimungal (1:35)

It's an honor that you chose your first English podcast to be here. So you said there is truth in this world and we can know it.

Hirosi Ooguri (1:43)

Right.

I think I wrote it somewhere. I might say that in my public lectures too, yes.

Curt Jaimungal (1:50)

In Beijing.

Hirosi Ooguri (1:51)

Yeah. For example, in Beijing and also maybe in Tokyo and also Copenhagen, maybe, yes.

Curt Jaimungal (1:57)

So what do you mean by that?

Hirosi Ooguri (1:59)

Oh, okay. So this was actually in the context of why I became interested in theoretical physics when I became interested in becoming a theoretical physicist. That was actually pretty early.

So I was, I think, about fifth grade. And so I can tell you the experience that led to that. So, you know, about around the fifth, sixth grade, we learned about elementary geometry, like similarity of triangles and squares. And one of the first things we did with our teacher was to go out to the schoolyard. There was a telephone tower at the end of the schoolyard. And we used the similarity to measure the height of the telephone tower.

So we saw the angle to the top of the telephone tower, and we measured the distance to the telephone tower. And then we can use similarity to estimate the height of the telephone tower. And so I thought that was cool. And so then after a few months, so my parents used to take me to some, so I actually grew up in rural area in Japan. So I went to public school all the way from elementary school to high school. My parents didn't go to college, so I didn't know much about what higher education is gonna be like, but I liked reading books. And my parents used to take me to bigger city in weekend, and there is a particular restaurant where you enjoy having lunch. And it was like 12-story restaurant, and it was actually, you know, do you know one of those revolving restaurant?

So that there was a scenic, historical structure that you go around. So that was my favorite restaurant, so my parents often took me there. And so I was looking out to the goodful scenery, and so there was Horizon. So I was wondering how far the Horizon is, okay? And so since I learned about this triangulation, so I thought, well, maybe you can use similarity to estimate the distance to the Horizon, okay? So it's a simple geometric question. So it was revolving, and by the time it came back, so I was able to figure out that if you take the product of the height of the building and the radius of the Earth, and then it's actually square of the distance to the Horizon. Now, I was wrong about it, actually. There was a factor two error in this estimate, but this was like that. So essentially the distance to the Horizon is what you call geometric mean of the height of the building and the size of the Earth.