What does Landau mean by irreproducible measurement results?

[alanzhu]

In page 23 of Landau's "Quantum Mechanis", he said:"The results of measurements in quantum mechanics cannot be reproduced."what's this means?

 

[HallsofIvy]

Fairly obvious isn't it? Since, by the Heisenberg uncertainty principle, you can never set up the experiment in exactly the same way, you cannot guarantee exactly the same results.

Advocates of the Copenhagen Interpretation would say that result of the "wave collapse" is random so that even if you could set up exactly the same conditions, you would not get exactly the same results.

 

[Nacho]

Advocates of the Copenhagen Interpretation would say that result of the "wave collapse" is random so that even if you could set up exactly the same conditions, you would not get exactly the same results.

No, I'm an advocate of the Copenhagen Interpretation, and I'd say that the so called "wave collapse" had no bearing whatsoever on the outcome of the measurement. It is nothing other than a method to predict odds of what could happen in a measurement. Nothing more .. certainly nothing with a physical meaning, or "result". Its "collapse" means nothing other than it has no predictive power anymore.