Sean Carroll

Why can't we have electrons A and B entangled such that if I measure A and find it at coordinates one, two, three, then I immediately know that B is at coordinates minus one, minus two, minus three. You can. Sure. No problem at all. In fact, that's a very, very common form of entanglement. We don't even talk about it that much because it's just so common.

But, you know, the example that I often use is imagine a particle like the Higgs boson. Picking the Higgs boson just because it has no spin, so we're not worried about spin at all. It decays. It decays into an electron and a positron. And the prediction, according to the Schrodinger equation, is that if you ask in what direction will the electron be moving?

But, you know, the example that I often use is imagine a particle like the Higgs boson. Picking the Higgs boson just because it has no spin, so we're not worried about spin at all. It decays. It decays into an electron and a positron. And the prediction, according to the Schrodinger equation, is that if you ask in what direction will the electron be moving?

The answer is the wave function spreads out in all directions. It is equally likely, because there was no spin for the original Higgs boson, so there was no orientation, no special direction of space was picked out, equal probability to observe the electron moving in any one position, likewise in any one direction.

The answer is the wave function spreads out in all directions. It is equally likely, because there was no spin for the original Higgs boson, so there was no orientation, no special direction of space was picked out, equal probability to observe the electron moving in any one position, likewise in any one direction.

Likewise for the positron, equal probability to observe it moving in any one direction. But when you observe one, then you know where the other one is because momentum is conserved. You know exactly what the coordinates has to be for the other particle that you didn't observe. There you go. And that's entanglement.

Likewise for the positron, equal probability to observe it moving in any one direction. But when you observe one, then you know where the other one is because momentum is conserved. You know exactly what the coordinates has to be for the other particle that you didn't observe. There you go. And that's entanglement.

Indeed, that is more or less what EPR actually talked about in the famous Einstein-Podolsky-Rosen paper about entanglement. The idea of doing it with spins came later. It might have been John Bell, actually, who originally popularized the idea of doing it with spins. I'm not sure about that. David Summers says, I finally got around to watching Oppenheimer.

Indeed, that is more or less what EPR actually talked about in the famous Einstein-Podolsky-Rosen paper about entanglement. The idea of doing it with spins came later. It might have been John Bell, actually, who originally popularized the idea of doing it with spins. I'm not sure about that. David Summers says, I finally got around to watching Oppenheimer.

In your opinion, how valid was the concern that the atmosphere could ignite when detonating an atomic bomb? Was it irresponsible to carry out the test given the available information at the time? Well, I can certainly say that the movie overhyped that particular worry. The worry did exist, or rather, let's put it this way, the possibility had been raised.

In your opinion, how valid was the concern that the atmosphere could ignite when detonating an atomic bomb? Was it irresponsible to carry out the test given the available information at the time? Well, I can certainly say that the movie overhyped that particular worry. The worry did exist, or rather, let's put it this way, the possibility had been raised.

There was never a time when someone did a calculation and they said, oh, this will ignite the atmosphere, okay? Rather, people suggested, like, is it possible that this will ignite the atmosphere? Should we worry about that? And they did the best they could. They tried to calculate it, and they found out that the answer was no. It would not ignite the atmosphere, so they moved on.

There was never a time when someone did a calculation and they said, oh, this will ignite the atmosphere, okay? Rather, people suggested, like, is it possible that this will ignite the atmosphere? Should we worry about that? And they did the best they could. They tried to calculate it, and they found out that the answer was no. It would not ignite the atmosphere, so they moved on.

Now, it's completely legitimate to say, okay, but there was a chance, there was a chance it would ignite the atmosphere, and how exactly confident were they that it wouldn't happen, right? Isn't that kind of important?

Now, it's completely legitimate to say, okay, but there was a chance, there was a chance it would ignite the atmosphere, and how exactly confident were they that it wouldn't happen, right? Isn't that kind of important?

That's very true, and it's something I'm actually very interested in and not completely clear about in my own brain, how to deal with these things that you think are very, very unlikely but hugely consequential if they happen.

That's very true, and it's something I'm actually very interested in and not completely clear about in my own brain, how to deal with these things that you think are very, very unlikely but hugely consequential if they happen.

One of the aspects to keep in mind is lots of things, other than setting off a nuclear test, have the property that they could, in principle, cause some tremendous calamity to happen, and you don't know what the probability is, okay? When I wrote my book on the Higgs boson, the particle at the end of the universe, that was a worry, right?

One of the aspects to keep in mind is lots of things, other than setting off a nuclear test, have the property that they could, in principle, cause some tremendous calamity to happen, and you don't know what the probability is, okay? When I wrote my book on the Higgs boson, the particle at the end of the universe, that was a worry, right?

The worry was that by turning on the LHC, the Large Hadron Collider, we would destroy the Earth eventually. And I said, look, every time you open a jar of spaghetti sauce, pasta sauce, there is a possibility that some random mutation brought to life a terrible mutated pathogen that you are now releasing into the world and will kill all life on Earth by opening that jar of pasta sauce. Unlikely.