Hello, everyone. Welcome to the Mindscape Podcast. I'm your host, Sean Carroll. We had a

AMA question a couple of weeks ago earlier this month that I'm not sure I did a great job of

answering. You know, I tried to give an impression of what was in my mind. The question was

about the difference between complexity in the sense of complex systems research versus simply being complicated.

I've actually invoked this distinction before.

They're not the same thing, but neither word really has an agreed upon single definition.

So I kind of said that.

And I said, well, it's up to whoever is speaking.

You can mean different things. But it occurred to me later when thinking about today's

podcast that you're about to hear that there is sort of a single thing you can put your finger

on that really distinguishes simply being complicated from being complex in the sense that we

use it, which is complicated means there's a lot of stuff

going on. Complexity happens when there's a lot of stuff going on, and those things interact

with each other so that in some sense the whole system of interacting complicated things going

on forms a whole. There is some notion of the system arising out of the smaller

pieces in a way that still makes the pieces be important. So it's different than the very,

very simple-minded notions of emergence that we have sometimes in physics, where you have,

you know, atoms coming together to make a fluid. That's absolutely true. You have many, many,

many atoms, and they come together and they interact to make a fluid. But then once you have that

fluid description as a gas or a liquid or whatever, you can forget about the atoms, right? You can

sort of average over what all the atoms are doing and get a pretty good higher level description

of what's happening. In a complex system,

...