Classical paths and bubble chambers

[jackle]

It is often said that electrons do not follow classical paths, especially in the context of electrons in atoms etc. I have absolutely no problem with this, as I do have a academic background in physics (but extremely rusty).

Non-classical paths, uncertainty etc. being the case, what is then being shown in a bubble chamber if not a classical path? I am a bit embarrassed that I don't know the answer. Is it just that the uncertainty is too small to be relevant in a bubble chamber? I suppose bubbles in a liquid aren't exactly accurate measurements of anything right? So when a particle interacts to make bubbles, what have we actually measured? What happens to the wave function?

 

[ZapperZ]

It is often said that electrons do not follow classical paths, especially in the context of electrons in atoms etc. I have absolutely no problem with this, as I do have a academic background in physics (but extremely rusty).

Non-classical paths, uncertainty etc. being the case, what is then being shown in a bubble chamber if not a classical path? I am a bit embarrassed that I don't know the answer. Is it just that the uncertainty is too small to be relevant in a bubble chamber? I suppose bubbles in a liquid aren't exactly accurate measurements of anything right? So when a particle interacts to make bubbles, what have we actually measured? What happens to the wave function?

But in a bubble chamber, the charge particles (not necessarily just electrons) are now interacting with many other particles. It is also considered to be "free" particles and is not encumbered by the usual boundary conditions we get in atoms. They are also usually widely separated from each other (no significant wavefunction overlap). So other than the coulombic interactions, they are non-correlated.

Also note that in electron particle accelerators, the electrons are also handled as classical particles. So such treatement isn't unusual.

Zz.

 

[jackle]

It says in Wikipedia that you can't measure the kinetic energy or velocity in a bubble chamber.

http://en.wikipedia.org/wiki/Bubble_chamber

Do you know if this is because of the uncertainty principle?

 

[ZapperZ]

It says in Wikipedia that you can't measure the kinetic energy or velocity in a bubble chamber.

http://en.wikipedia.org/wiki/Bubble_chamber

Do you know if this is because of the uncertainty principle?

No, it's because all it can measure are "tracks", i.e. in where and in which direction the particle is moving. If the bubble chamber is also in a magnetic field that bends the charged particle, then it can measure its energy. To measure energy or velocity, you have to SET UP an experiment that measures those quantities. A single measurement does not imply the measurement of ALL properties. This has nothing to do with the HUP.

Zz.

 

[quetzalcoatl9]

the dynamics of a bubble chamber are of sufficient scale that classical mechanics will work just fine

 

[jackle]

OK. Thanks.