Sean Carroll

The Dirac equation and the Klein-Gordon equation are both classical equations of motion for fields. The Klein-Gordon equation is the classical equation of motion for a spinless field. The Dirac equation is the classical equation of motion for a spin-1 field that has electric charge.

The Dirac equation and the Klein-Gordon equation are both classical equations of motion for fields. The Klein-Gordon equation is the classical equation of motion for a spinless field. The Dirac equation is the classical equation of motion for a spin-1 field that has electric charge.

Okay, so it includes both the electron, spin up and spin down, and the positron, spin up and spin down, the particle and its antiparticle. So Dirac thought that he was generalizing the Schrodinger equation, but it turns out that that's not what he was doing, okay? So the correct interpretation, and people sort of hang on to that mistake.

Okay, so it includes both the electron, spin up and spin down, and the positron, spin up and spin down, the particle and its antiparticle. So Dirac thought that he was generalizing the Schrodinger equation, but it turns out that that's not what he was doing, okay? So the correct interpretation, and people sort of hang on to that mistake.

It sounds good when you say, well, there was Schrodinger, and he had the non-relativistic thing, and then Dirac came along and he made it relativistic. The relativistic thing is quantum field theory. That's what the relativistic thing is. But even in quantum field theory, you start with the classical field, And Dirac and Klein and Gordon gave us equations for those classical fields.

It sounds good when you say, well, there was Schrodinger, and he had the non-relativistic thing, and then Dirac came along and he made it relativistic. The relativistic thing is quantum field theory. That's what the relativistic thing is. But even in quantum field theory, you start with the classical field, And Dirac and Klein and Gordon gave us equations for those classical fields.

And then you quantize it. And there's different ways of quantizing the field. And one way is precisely analogous to what Schrödinger did for a single electron, namely to invent a wave function that is a function of the field rather than a function of the particle. And that wave function obeys an equation, and that equation is called the Schrodinger equation.

And then you quantize it. And there's different ways of quantizing the field. And one way is precisely analogous to what Schrödinger did for a single electron, namely to invent a wave function that is a function of the field rather than a function of the particle. And that wave function obeys an equation, and that equation is called the Schrodinger equation.

The Schrodinger equation is completely general in terms of does it describe non-relativistic things, relativistic things? Yes. There are different versions of the Schrodinger equation that apply to any of those individual circumstances. Indeed, there's a version of the Schrodinger equation that applies to a single qubit, right?

The Schrodinger equation is completely general in terms of does it describe non-relativistic things, relativistic things? Yes. There are different versions of the Schrodinger equation that apply to any of those individual circumstances. Indeed, there's a version of the Schrodinger equation that applies to a single qubit, right?

A single degree of freedom that is either spin up or spin down, which is not a field at all. For every quantum system, there is a Schrodinger equation, even for the relativistic ones. Supine Otter asks a priority question, continuing in the spirit of asking someone who doesn't like tattoos about tattoos.

A single degree of freedom that is either spin up or spin down, which is not a field at all. For every quantum system, there is a Schrodinger equation, even for the relativistic ones. Supine Otter asks a priority question, continuing in the spirit of asking someone who doesn't like tattoos about tattoos.

You previously suggested your favorite equations to ink on one's body, but for the visually inclined, can you recommend the physics-related diagrams or images that are most meaningful, satisfying, or beautiful to you and would make a great tattoo? It's a good question, a perfectly legit question.

You previously suggested your favorite equations to ink on one's body, but for the visually inclined, can you recommend the physics-related diagrams or images that are most meaningful, satisfying, or beautiful to you and would make a great tattoo? It's a good question, a perfectly legit question.

I'm going to probably not give you a great answer just because, well, anyone who gets a tattoo shouldn't listen to me about what tattoo to get. And not because I don't like tattoos, because they shouldn't listen to anyone about what tattoo to get. They should... Think of it themselves, right? I mean, do you care about thermodynamics? Do you care about general relativity?

I'm going to probably not give you a great answer just because, well, anyone who gets a tattoo shouldn't listen to me about what tattoo to get. And not because I don't like tattoos, because they shouldn't listen to anyone about what tattoo to get. They should... Think of it themselves, right? I mean, do you care about thermodynamics? Do you care about general relativity?

Do you care about quantum mechanics or whatever? These would all suggest different tattoos you could get. I mean, you could be playful. You could get a tattoo of Schrodinger's cat, right, of being both awake and asleep at the same time. you could get a tattoo of a space-time diagram.

Do you care about quantum mechanics or whatever? These would all suggest different tattoos you could get. I mean, you could be playful. You could get a tattoo of Schrodinger's cat, right, of being both awake and asleep at the same time. you could get a tattoo of a space-time diagram.

You know, there's some very nice Penrose diagrams, like the Penrose diagram for the eternal Schwarzschild black hole is a very nice little diagram, pretty simple. You could shade it in if you wanted to make it look a little more complicated or something like that.

You know, there's some very nice Penrose diagrams, like the Penrose diagram for the eternal Schwarzschild black hole is a very nice little diagram, pretty simple. You could shade it in if you wanted to make it look a little more complicated or something like that.