Sean Carroll

This is to say, for those of you who have not read that wonderful book that I can absolutely recommend to you, you can formulate the laws of physics either in sort of the good old-fashioned Laplace's demon way, which is to say, give me the complete state of the system now, give me the equations of motion, I will tell you what happens next. The Laplacian paradigm, we called it in the book.

This is to say, for those of you who have not read that wonderful book that I can absolutely recommend to you, you can formulate the laws of physics either in sort of the good old-fashioned Laplace's demon way, which is to say, give me the complete state of the system now, give me the equations of motion, I will tell you what happens next. The Laplacian paradigm, we called it in the book.

And that is how Hamiltonian mechanics works. Lagrangian mechanics is based on what's called the principle of least action. You may have heard about it. And it says, don't tell me exactly the state of the system to start. Tell me the configuration of the system. Tell me the positions, but not the velocities, for example, of the system.

And that is how Hamiltonian mechanics works. Lagrangian mechanics is based on what's called the principle of least action. You may have heard about it. And it says, don't tell me exactly the state of the system to start. Tell me the configuration of the system. Tell me the positions, but not the velocities, for example, of the system.

but then also tell me the configuration of the system at some other time. And I'm going to search through all possible ways to connect the configuration at the early time to the configuration at the late time. I'm going to choose the one that minimizes a certain number called the action. So you can show that the actual behavior of systems under these two ways of talking are completely equivalent.

but then also tell me the configuration of the system at some other time. And I'm going to search through all possible ways to connect the configuration at the early time to the configuration at the late time. I'm going to choose the one that minimizes a certain number called the action. So you can show that the actual behavior of systems under these two ways of talking are completely equivalent.

But the actual procedure you go through to get them is very, very different. In a slightly more advanced version of this, these days we talk about the ADS-CFT duality and other dualities in quantum field theory. A duality is exactly this. A duality is two different ways of talking about exactly the same underlying physics, two different equivalent ways of talking.

But the actual procedure you go through to get them is very, very different. In a slightly more advanced version of this, these days we talk about the ADS-CFT duality and other dualities in quantum field theory. A duality is exactly this. A duality is two different ways of talking about exactly the same underlying physics, two different equivalent ways of talking.

In quantum mechanics, we have the Schrodinger picture and the Heisenberg picture. There's a whole bunch of different examples where you have multiple ways of doing things. I don't know whether there are examples where choosing a particular orientation has led to a research breakthrough. Probably yes, but I don't know off the top of my head.

In quantum mechanics, we have the Schrodinger picture and the Heisenberg picture. There's a whole bunch of different examples where you have multiple ways of doing things. I don't know whether there are examples where choosing a particular orientation has led to a research breakthrough. Probably yes, but I don't know off the top of my head.

But absolutely it's true that choosing a particular orientation changes how you naturally think about things, right? It changes the sort of natural ways to – modify the theory or think about different theories. Anyway, I don't have any perfect examples of that off the top of my head right now.

But absolutely it's true that choosing a particular orientation changes how you naturally think about things, right? It changes the sort of natural ways to – modify the theory or think about different theories. Anyway, I don't have any perfect examples of that off the top of my head right now.

But for presentism versus eternalism, you know, if you, you know, presentists, I should say, I'm an eternalist myself. So I think of the whole shebang, right? I think of, you know, the whole universe all at once and try to figure out what rules it obeys and things like that. Someone like Tim Maudlin, former Mindscape guest, is a presentist.

But for presentism versus eternalism, you know, if you, you know, presentists, I should say, I'm an eternalist myself. So I think of the whole shebang, right? I think of, you know, the whole universe all at once and try to figure out what rules it obeys and things like that. Someone like Tim Maudlin, former Mindscape guest, is a presentist.

He really thinks that the laws of physics not only describe patterns in the evolution of the universe, but bring them about. He's not only a presentist, but an anti-Humian when it comes to laws of physics, as we talked about with Tim, but also previously with Ned Hall, etc. So Barry Lower and I talked about that also.

He really thinks that the laws of physics not only describe patterns in the evolution of the universe, but bring them about. He's not only a presentist, but an anti-Humian when it comes to laws of physics, as we talked about with Tim, but also previously with Ned Hall, etc. So Barry Lower and I talked about that also.

So that does lead these individuals, myself, Tim Maudlin, et cetera, to propose different theories of understanding. You know, Tim is not happy with many worlds. He's much happier with Bohmian mechanics. I'm kind of appalled by Bohmian mechanics. Which one of us is right will hopefully be decided by data and things like that in the future.

So that does lead these individuals, myself, Tim Maudlin, et cetera, to propose different theories of understanding. You know, Tim is not happy with many worlds. He's much happier with Bohmian mechanics. I'm kind of appalled by Bohmian mechanics. Which one of us is right will hopefully be decided by data and things like that in the future.

But in the meantime, since we don't know the answer, our orientations are absolutely going to affect what we're most likely most positively predisposed toward. Robert F. asks a priority question.

But in the meantime, since we don't know the answer, our orientations are absolutely going to affect what we're most likely most positively predisposed toward. Robert F. asks a priority question.