Sean Carroll

ever exchange photons given that the Doppler effect will alter the frequency? Well, there's a lot going on here and I'm actually not the best person to ask about what is going on in the receptors in our eyes or things like that. But I think part of it is there are many different frequencies.

ever exchange photons given that the Doppler effect will alter the frequency? Well, there's a lot going on here and I'm actually not the best person to ask about what is going on in the receptors in our eyes or things like that. But I think part of it is there are many different frequencies.

So indeed, in the cartoon model of an atom or a molecule, there are electrons in orbitals with very, very specific energies. So you might think that unless you hit that energy right on, you're not going to be able to excite that particular electron. But typically, the photons that are moving around doing the exciting are not in what we call energy eigenstates.

So indeed, in the cartoon model of an atom or a molecule, there are electrons in orbitals with very, very specific energies. So you might think that unless you hit that energy right on, you're not going to be able to excite that particular electron. But typically, the photons that are moving around doing the exciting are not in what we call energy eigenstates.

That is to say, they don't have perfectly precise, well-defined energies. That's part of the fun of quantum mechanics. in exactly the same way that an electron itself, which if we imagine that it is exactly in a perfectly definite state of energy, it will then not be in a perfectly definite state of position. We think of the electron as being in a superposition of many different positions.

That is to say, they don't have perfectly precise, well-defined energies. That's part of the fun of quantum mechanics. in exactly the same way that an electron itself, which if we imagine that it is exactly in a perfectly definite state of energy, it will then not be in a perfectly definite state of position. We think of the electron as being in a superposition of many different positions.

these photons are typically going to be in superpositions of many different energies. So the energy has to be pretty close to the right answer to poke the electron around in the right way. But there's probably some uncertainty around that exact right answer. And as long as the electron's energy is within that uncertainty band, you have a probability of making this happen.

these photons are typically going to be in superpositions of many different energies. So the energy has to be pretty close to the right answer to poke the electron around in the right way. But there's probably some uncertainty around that exact right answer. And as long as the electron's energy is within that uncertainty band, you have a probability of making this happen.

Remember, all of quantum mechanics is about probabilities for these things happening. And likewise, yes, the electrons are going to be moving back and forth. They're going to have Doppler effects in the photons that they emit and absorb. But that's sort of helping them, right?

Remember, all of quantum mechanics is about probabilities for these things happening. And likewise, yes, the electrons are going to be moving back and forth. They're going to have Doppler effects in the photons that they emit and absorb. But that's sort of helping them, right?

In the sense that if you have many different molecules and they, you know, molecular energy levels are generally tightly compressed. There's a lot of them. So it's not just like the one or two that you see in the cartoon of the hydrogen atom and so forth, right?

In the sense that if you have many different molecules and they, you know, molecular energy levels are generally tightly compressed. There's a lot of them. So it's not just like the one or two that you see in the cartoon of the hydrogen atom and so forth, right?

So if you have the molecules moving or the photons moving, so there's not only some uncertainty in energy but some shift in energy because of the Doppler effect, it is more likely that some of the photons are going to be in the right band to do the action.

So if you have the molecules moving or the photons moving, so there's not only some uncertainty in energy but some shift in energy because of the Doppler effect, it is more likely that some of the photons are going to be in the right band to do the action.

I suspect that—and I don't know this for sure, so you should talk to a real biologist—but I suspect that in the eye, when there is an electrochemical receptor that fires, the probability of that happening per photon, I suspect, is pretty small. I don't know that, but we have a lot of photons in the world. I think that there is some controversy.

I suspect that—and I don't know this for sure, so you should talk to a real biologist—but I suspect that in the eye, when there is an electrochemical receptor that fires, the probability of that happening per photon, I suspect, is pretty small. I don't know that, but we have a lot of photons in the world. I think that there is some controversy.

Now that I'm thinking about it, there's some uncertainty about, you know, is the eye sensitive enough to detect a single photon? And maybe the answer is sometimes it is, sometimes it isn't, depending on what's going on. But anyway, I think the basic lesson here is there's a lot of uncertainty in quantum mechanics, and this is an example where that actually helps us out.

Now that I'm thinking about it, there's some uncertainty about, you know, is the eye sensitive enough to detect a single photon? And maybe the answer is sometimes it is, sometimes it isn't, depending on what's going on. But anyway, I think the basic lesson here is there's a lot of uncertainty in quantum mechanics, and this is an example where that actually helps us out.

Cole Giusto says, in the big picture, you emphasize that emergent phenomena are still real even if they're not fundamental. How do you differentiate important ontological disagreements from semantics? In what way do you think real has a definite meaning that is worth arguing for? You know, whether it's worth arguing for or not, I think that's a bit of a judgment call, right? And very often...

Cole Giusto says, in the big picture, you emphasize that emergent phenomena are still real even if they're not fundamental. How do you differentiate important ontological disagreements from semantics? In what way do you think real has a definite meaning that is worth arguing for? You know, whether it's worth arguing for or not, I think that's a bit of a judgment call, right? And very often...