Quantum tunnelling - what is real?

[ZapperZ]

I don't know how you got the impression that that I am questioning the validity of any experiment. I am becoming more inclined to believe that you did not really grasp the direction of my initial question. You state that no detectors have been out inside a tunnelling barrier to detect the tunnelling particle. That is useful information thank you. But would it be ever possible to? I am now thinking probably not.

And I don't think you really grasp what I've been trying to tell you all along!

Your original question, if you look at it again, seemed to question "what is real" as far as what goes on inside the barrier. It was as if it is a requirement that there needs to be some 'detector' inside the barrier for there to be ANY acceptance of any validity of the physics in there.

I argued that we have OTHER MEANS of knowing what goes on in there. I gave you an example of adding magnetic impurities to superconducting tunnel junctions, where magnetic impurities inside the barrier can have a strong effect, just as expected and predicted, on the tunneling spectrum. I argued that the agreement between theory and experiment is ONE way we can measure what goes on inside the barrier. I also argue that this technique is essentially what we have been doing all along in understanding and verifying ALL of our observations.

That is why I do not understand why there is this issue that we don't know what is going on inside the barrier, considering that there is no issue on what is going on elsewhere in the tunneling process.

Zz.

 

[anorlunda]

Professor Susskind touched on this question in one of his lectures. He said that if you calculate the minimum energy required to detect the particle inside the barrier, the answer is exactly the same energy needed to lift the particle over the barrier without tunneling. That would leave you with a paradoxical result; did it tunnel or not?

That is the end result of all experiments that try to peer into the inner workings of quantum mechanics to see more details than quantum mechanical mathematics tell. They all fail. That is not intuitive or satisfying, but it is true.

 

[Jilang]

And I don't think you really grasp what I've been trying to tell you all along!

Your original question, if you look at it again, seemed to question "what is real" as far as what goes on inside the barrier.

Zz.

I don't think you read past the title of the thread. I was asking if the existence of a non vanishing wavefunction would lead to any chance of it actually being found there.

 

[Jilang]

Professor Susskind touched on this question in one of his lectures. He said that if you calculate the minimum energy required to detect the particle inside the barrier, the answer is exactly the same energy needed to lift the particle over the barrier without tunneling. That would leave you with a paradoxical result; did it tunnel or not?

That is the end result of all experiments that try to peer into the inner workings of quantum mechanics to see more details than quantum mechanical mathematics tell. They all fail. That is not intuitive or satisfying, but it is true.

Thanks Anorlunda, that ties in with what the guys at Toronto concluded (see post #18).

 

[ZapperZ]

I don't think you read past the title of the thread. I was asking if the existence of a non vanishing wavefunction would lead to any chance of it actually being found there.

... and what did you think I've been trying to show you all along? This leads me to believe that you really haven't understood the magnetic impurity discussion.

I think I'm done here.

Zz.

 

[Jilang]

... and what did you think I've been trying to show you all along? This leads me to believe that you really haven't understood the magnetic impurity discussion.

I think I'm done here.

Zz.

Thanks Zzz, I do appreciate your input.