Why don't the Slits collapse the wave function?

Click For Summary
The discussion centers on the phenomenon of wave function collapse in quantum mechanics, particularly in the context of the double-slit experiment. Participants explore why the interaction with the slits does not collapse the wave function, while a measurement does, emphasizing that the slits do not randomize the phase of the wave function. The concept of internal degrees of freedom is introduced, suggesting that if the slits or impurities can change state upon interaction, they could disrupt the phase coherence necessary for interference patterns. The conversation also touches on the nature of measurement in quantum mechanics, indicating that it is not clearly defined when or how a measurement occurs. Overall, the dialogue reflects a deep engagement with the complexities of quantum behavior and the implications of measurement.
  • #91
DrChinese said:
There is a way to learn which slit the photon pass through without absorbing it. If you put a polarizer in front (or behind) each slit, and the polarizers are crossed (at 90 degrees apart as to their relative orientation), then the photon passes through. Because of the polarizer, you know which slit it passed through (or could learn later); therefore there is no interference pattern.

I can see two situations here. If we send toward the slits a circular polarized photon, then each component of linear polarization would pass through each slit and then re-combine. The interference pattern would still be there.
If we sent a linearly polarized photon with either horizontal or vertical polarization, then we would know which slit it went through. Every photon that lands on the screen would be coming from the slit that corresponds to its initial polarization. In this case I guess the interference pattern would be destroyed. But I also think that 50% of the time the photon would be absorbed by the polarizer film in the slit with crossed polarization. If you use a polarizer that works by reflection, in that case you could absorb the photon after being reflected. So I don't know if this would qualify as a non-absorption detection experiment. It would also be equivalent to putting any obstacle in front of one of the slits. What you are detecting is the photon that doesn't make it through and not the one that does.
Well Dr. Chinese you got me thinking for a while. This is an interesting modification of the double-slit experiment and I had fun thinking about it.
 

Similar threads

High School The wave function of the electron doesn't collapse when passing through air?
  • · Replies 9 ·
Replies
9
Views
2K
High School Why does anyone think gravity might collapse wave function?
  • · Replies 59 ·
2
Replies
59
Views
7K
High School How is energy transferred from a wave to a photon?
  • · Replies 18 ·
Replies
18
Views
3K
Undergrad Is There A Study Showing The Observer Effect Ignoring Conscious Intent?
  • · Replies 3 ·
Replies
3
Views
4K
Undergrad How non-conscious can an Observer be and cause wave function collapse?
  • · Replies 23 ·
Replies
23
Views
7K
High School Can someone please explain to me the motion of an electron?
  • · Replies 11 ·
Replies
11
Views
2K
High School Why doesn't the electron "wave" collapse at the double-slit?
  • · Replies 28 ·
Replies
28
Views
7K
High School Wave Function Collapse using faulty recording devices.
  • · Replies 7 ·
Replies
7
Views
2K
Graduate Can particles appear and disappear "with" a cause?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad "Wave-particle duality" and double-slit experiment
  • · Replies 36 ·
2
Replies
36
Views
8K