Does Heisenberg apply to a collapsed wavefunction?

[bhobba]

"Measurement" is not a purely physical term but is related to how a person acquires knowledge. If you remove the pointer from your amperemeter, you don't have a measurement apparatus anymore although the physical interaction between your system of interest and the amperemeter doesn't change.

This is part of the difficulty with the whole measurement paradigm of what QM is and why its a difficult issue.

Basically in modern times a measurement is replaced with dechoherence which is independent of pointers in measurement apparatus etc. But this is an advanced issue best glossed over for HS students.

Thanks
Bill

 

[T'Pau]

Hi,

And 'collisions' and 'particle-like-behaviour', are these more or less synonyms?

-> is there particle-like-behaviour that does not involve collisions?

Paul, who is grateful for al the responses.

 

[atyy]

Hi,

And 'collisions' and 'particle-like-behaviour', are these more or less synonyms?

-> is there particle-like-behaviour that does not involve collisions?

Paul, who is grateful for al the responses.

Tricky, tricky, tricky.

Yes, collisions are particle like behaviour.

However, in LHC type collisions, the rough idea is that one sends in free, non-interacting particles, the particles collide and interact, and then the outgoing particles from the collision are again free, non-interacting particles. The tricky part is that a free particle from a collision is the most unlocalized state, because it is a particle with a definite momentum. Since it has a definite momentum, it must have very undefinite position. But then what about all those particle tracks? Well, although the tracks looks small and localized to us, they are big from the point of view of the uncertainty principle.

http://books.google.com/books?id=CNCHDIobj0IC&vq=particle&source=gbs_navlinks_s
p117: To a particle the beam is the whole universe, and it is big!