Sean Carroll

But spatial locality was used to separate types of emergence. Couldn't the analogous thing be done for spatial locality, where knowledge about other locations is contained at each location, making the dynamic local? Is there some crucial difference between time and space that I am missing? Yes, there is a very crucial difference between time and space that you are missing. This is subtle.

But spatial locality was used to separate types of emergence. Couldn't the analogous thing be done for spatial locality, where knowledge about other locations is contained at each location, making the dynamic local? Is there some crucial difference between time and space that I am missing? Yes, there is a very crucial difference between time and space that you are missing. This is subtle.

You know, we all know that Einstein came along and said that in some sense, time and space are both part of a single underlying space-time. You want to say that, and you want to appreciate it, and you want to take it on board in your precious belief set. But you also want to understand that there are still differences between time and space.

You know, we all know that Einstein came along and said that in some sense, time and space are both part of a single underlying space-time. You want to say that, and you want to appreciate it, and you want to take it on board in your precious belief set. But you also want to understand that there are still differences between time and space.

The single biggest difference, I would say, there's a lot of differences, but the single biggest one is time. given information about the universe at one moment in time, you can, in principle, in classical mechanics, predict what it will be like at other moments of time, right? That's Laplace's demon that we were just talking about. There is no analogous statement for space, okay?

The single biggest difference, I would say, there's a lot of differences, but the single biggest one is time. given information about the universe at one moment in time, you can, in principle, in classical mechanics, predict what it will be like at other moments of time, right? That's Laplace's demon that we were just talking about. There is no analogous statement for space, okay?

So the table I have right in front of me right now, it has atoms in it. The atoms have a certain density, right? And knowing the density of atoms, the number, you know, the amount of grams per cubic centimeter at one location of the table does not help me predict what the density of matter is like a few centimeters away, because the table might end, right?

So the table I have right in front of me right now, it has atoms in it. The atoms have a certain density, right? And knowing the density of atoms, the number, you know, the amount of grams per cubic centimeter at one location of the table does not help me predict what the density of matter is like a few centimeters away, because the table might end, right?

There's a sharp line where the table is to the left and it's not to the right. There's a discontinuity in the density of matter. But if I think about, so over space, there's just complete difference from place to place. There's no determination from what happens at one point to what happens at the other point. But there is a determination in time.

There's a sharp line where the table is to the left and it's not to the right. There's a discontinuity in the density of matter. But if I think about, so over space, there's just complete difference from place to place. There's no determination from what happens at one point to what happens at the other point. But there is a determination in time.

If I say, okay, there's a certain amount of energy density here at one moment of time, what's it going to be like a minute later? It depends on details, but probably it's going to be the same number, right? The table's not really moving. So there is this rigidity, there's this predictability from moment to moment in time that simply isn't there in space.

If I say, okay, there's a certain amount of energy density here at one moment of time, what's it going to be like a minute later? It depends on details, but probably it's going to be the same number, right? The table's not really moving. So there is this rigidity, there's this predictability from moment to moment in time that simply isn't there in space.

And this has to do with the fact that there is only one dimension of time. This allows for that fact to happen. Mathematically, it has to do with the hyperbolic nature of the underlying differential equations. But there are three dimensions of space, so you don't quite have that same rigid control. So...

And this has to do with the fact that there is only one dimension of time. This allows for that fact to happen. Mathematically, it has to do with the hyperbolic nature of the underlying differential equations. But there are three dimensions of space, so you don't quite have that same rigid control. So...

Yes, in practice, for the reasons that we care about here, time and space are pretty different. There's predictability in time, not predictability in space. Anonymous says, I've noticed you almost never swear on the podcast. I'm curious if this is in order to be professional, or is that how you are in daily life as well? I think that in daily life, I swear more than I do on the podcast, okay?

Yes, in practice, for the reasons that we care about here, time and space are pretty different. There's predictability in time, not predictability in space. Anonymous says, I've noticed you almost never swear on the podcast. I'm curious if this is in order to be professional, or is that how you are in daily life as well? I think that in daily life, I swear more than I do on the podcast, okay?

I'm not afraid of swearing. I'm happy to do it. But yeah, I don't know whether you want to call it professional or not, but I do try to respect the audience and try to care about what the audience is. some members of the audience would probably like it better if I swore more. Some would not like it better.

I'm not afraid of swearing. I'm happy to do it. But yeah, I don't know whether you want to call it professional or not, but I do try to respect the audience and try to care about what the audience is. some members of the audience would probably like it better if I swore more. Some would not like it better.

I'm going to play it cautious and just try to be as accommodating for the largest number of people that I can. So when I give a talk, when I'm giving a colloquium or something like that, there's no swearing going on. When I give a public lecture, there might be children in the audience, there might be adults who just don't like it.

I'm going to play it cautious and just try to be as accommodating for the largest number of people that I can. So when I give a talk, when I'm giving a colloquium or something like that, there's no swearing going on. When I give a public lecture, there might be children in the audience, there might be adults who just don't like it.