High School How does a wave collapse not violate the speed of light?

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SUMMARY

The discussion centers on the concept of wave function collapse in quantum mechanics (QM) and its implications regarding the speed of light. Participants clarify that wave function collapse is not a physical process but a mathematical procedure used for predictions after measurements, specifically referencing the von Neumann projection postulate. The minimal math of QM does not support claims of anything traveling faster than light. The conversation emphasizes the importance of distinguishing between interpretations of QM and the mathematical framework that underpins it.

PREREQUISITES
  • Understanding of quantum mechanics fundamentals
  • Familiarity with the von Neumann projection postulate
  • Basic knowledge of wave-particle duality
  • Awareness of different interpretations of quantum mechanics
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  • Read the Insights article on the 7 basic rules of quantum mechanics
  • Explore various interpretations of quantum mechanics, such as Copenhagen and Many-Worlds
  • Study the mathematical framework of quantum mechanics, focusing on wave functions
  • Investigate the implications of measurement in quantum mechanics
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Students of physics, quantum mechanics enthusiasts, and researchers interested in the mathematical foundations of quantum theory and its interpretations.

TheCelt
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If you want to detect a particle in the 2 slit experiment on a detector. And we state that the electron is traveling as a wave so there is a wave front...that must mean that the wave front hits the detector at the same time in more than one place where there is constructive interference.

But since we detect a single point on the detector, would this mean the wave collapses faster than the speed of light, or even perhaps before it hits the detector entirely, i don't fully understand that part...Otherwise, why doesn't the detector detect the particle's wave front in a multitude of places at the same time, or perhaps it does and then that information is undone once the particle has collapsed to what ever location was ultimately picked ?

I don't actually study this topic in great detail i just mostly read as an observer so i am probably missing a lot of info here but it seems like the wave collapse would have to be instant which violates the speed of light? Am i thinking correctly here?
 
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@TheCelt,

How wave function collapse is handled depends on which interpretation of QM you adopt. Discussions of QM interpretations belong in the QM interpretations forum, not this one.

As far as the minimal math of QM that is needed to make predictions, that math makes no claim about whether wave function collapse is a real physical process or not; as far as the minimal math is concerned, wave function collapse is just a mathematical procedure that is used to make predictions after a measurement has been made and the result is known. That does not imply any claims about anything traveling faster than light.
 
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PeterDonis said:
As far as the minimal math of QM that is needed to make predictions, that math makes no claim about whether wave function collapse is a real physical process or not; as far as the minimal math is concerned, wave function collapse is just a mathematical procedure that is used to make predictions after a measurement has been made and the result is known. That does not imply any claims about anything traveling faster than light.

For clarity, the "minimal math of QM" is described in this Insights article:

https://www.physicsforums.com/insights/the-7-basic-rules-of-quantum-mechanics/

"Wave function collapse" as far as the minimal math is concerned is rule 7, also called the von Neumann projection postulate.
 
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Moderator's note: An off topic subthread arguing about what "collapse" means has been deleted. The meaning of "collapse" for purposes of this thread, and for purposes of this forum in general (as opposed to the QM interpretations forum, where the handling of "collapse" in various interpretations can be discussed), is as given in the previous post (now post #3 after the deletions).

The OP question has been answered and this thread is closed.
 

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