Sidney Coleman's opinion on interpretation in his Dirac lecture

[Demystifier]

Let's say yes. Why does it matter?

Because if you can prove it, you have solved the problem of measurement in QM and deserved the Nobel prize.

 

[martinbn]

Because if you can prove it, you have solved the problem of measurement in QM and deserved the Nobel prize.

But it is irrelevant for this thread!

 

[Demystifier]

But it is irrelevant for this thread!

On the contrary, it's crucial to it, for the reasons I and others explained several times.

 

[martinbn]

On the contrary, it's crucial to it, for the reasons me and others explained several times.

No, this thread is about what Coleman's done in the paper. Not about what you and others think Coleman should have done.

 

[Demystifier]

No, this thread is about what Coleman's done in the paper. Not about what you and others think Coleman should have done.

I argued that Coleman assumed interpretation B, according to which the observer does not distinguish different straight trajectories. It was you who asked me additional questions about the difference between interpretation B and interpretation A, and now you object that it is not relevant to the thread.

 

[martinbn]

I argued that Coleman assumed interpretation B, according to which the observer does not distinguish different straight trajectories. It was you who asked me additional questions about the difference between interpretation B and interpretation A, and now you object that it is not relevant to the thread.

You introduced the distiction between A and B, and insist that it is relevant, but you havent even tried to exlpain why.

 

[PeterDonis]

The problem is that Coleman's operators L and D are never actually measured, they are only "talked about".

What's the point of even talking about them if they don't correspond to any actual measurements we make?

The point of the argument was supposed to be to convince us that Coleman's interpretation, where there's just unitary evolution all the time, no other dynamics, explains why the world looks the way it does to us. How can any such explanation be valid if it doesn't even look at the operators that represent how we find out the way the world looks to us?

That said, I don't think Coleman intended for his operators L and D to only be "talked about". I think he intended them to represent actual things we do to find out how the world looks to us. I think he intended L to represent "the track in the cloud chamber is a definite straight line", and D to represent "we have a solid belief that the track in the cloud chamber is a definite straight line".

Those are indeed parts of how the world looks to us. The problem is that they are only parts, and they don't explain other parts. For example, the track in the cloud chamber isn't just some unspecified, but definite, straight line, which is all that L represents--it's some particular straight line, pointed in a particular direction. And we don't just have a solid belief that the track in the cloud chamber is some unspecified, but definite, straight line, which is all that D represents--we have a solid belief that it's some particular straight line, pointed in a particular direction.

Coleman doesn't address those other parts of how the world looks to us at all. And his L and D operators, if they are supposed to represent all of how the world looks to us regarding tracks in cloud chambers and our beliefs about them, simply, well, don't. I think he simply failed to consider that.