Why do particles act like waves

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Discussion Overview

The discussion centers around the question of why particles exhibit wave-like behavior, particularly in the context of the double slit experiment. Participants explore various theories and interpretations related to particle-wave duality, quantum field theory, and the nature of reality in quantum mechanics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants mention that particle-wave duality is 'explained' in quantum field theory, but the underlying reasons for this behavior remain unclear.
  • One participant argues that particles do not act like waves, suggesting that only narrow "wave packets" exhibit particle-like behavior.
  • Another participant emphasizes that the interference pattern represents a probabilistic distribution, where particles are treated as points, contrasting with the wave description that fills space.
  • A participant asserts that particles do not exist in a classical sense and must be understood in terms of quantum states, raising questions about the reality of wavefunctions and their collapse during measurement.
  • Some participants express that while quantum field theory may predict interference patterns, the fundamental 'why' behind this behavior is still unknown, similar to other unexplained phenomena in physics.
  • One participant suggests that the path integral formulation may provide insights, though they caution about the mathematical prerequisites for understanding it.
  • Another participant states that such 'why' questions may not be answerable, comparing it to asking why electrons exist.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the explanations for particle-wave behavior, with multiple competing views and interpretations presented throughout the discussion.

Contextual Notes

Participants highlight limitations in understanding the nature of particles and wavefunctions, as well as the dependence on interpretations of quantum mechanics. The discussion reflects ongoing debates about the reality of quantum states and the implications of different theoretical frameworks.

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What are the top theories as to why particles show the interference pattern in the double slit experiment.
 
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The particle-wave duality is 'explained' in quantum field theory.
 
Pjpic said:
What are the top theories as to why particles show the interference pattern in the double slit experiment.

Particles do not act like waves, and wave do not act like particles.
Only very narrow "wave packets" act like particles
 
malawi_glenn said:
The particle-wave duality is 'explained' in quantum field theory.

I see that the behavior of particles is described using waves, but I'm not finding where the 'why' is discussed.
 
Pjpic said:
I see that the behavior of particles is described using waves, but I'm not finding where the 'why' is discussed.

I said Quantum FIELD theory
 
malawi_glenn said:
I said Quantum FIELD theory

But how Quantum FIELD theory "explain it"?
 
feynmann said:
But how Quantum FIELD theory "explain it"?

The question was WHICH theory, not how ;-)

http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WB1-48CFHST-1-5W&_cdi=6697&_user=651519&_orig=search&_coverDate=06%2F30%2F2003&_sk=996949997&view=c&wchp=dGLzVzz-zSkWA&md5=8059eb26e8bb672bc86d8bc20684c63e&ie=/sdarticle.pdf

http://www.physnet.org/modules/pdf_modules/m246.pdf

There should probably exist good articles on American Journal of Physics.
 
The interference picture, consisting of "points", shows probabilistic space distribution. A particle is understood as a point solely so it is not possible to explain interference effects with (classical) "particle" theory. At the same time, waves fill the whole available space, not only one point in it. So the waves are used to describe the spatial spread of interference picture. Of course, they are not usual waves but waves of amplitude of probability. It is the experimental facts that lead to this (QM) picture.

Bob.
 
The explanation is unfortunately that particles as such do not exist. You will have to get rid of your concept of reality, which no one gives up without a fight. For quantum mechanics to work particles must exist in a "quantum state" in between measurements where they don't have exact positions, or speeds. This is all very well established classic quantum mechanics. There is pretty much just one theory about this and all the fancy other theories like quantum field theory, Bohmian mechanics, and even string theory (if it ever gets there) are build such that this theory is reproduced.
The main problem is interpretation, the question is still open how much reality we can get back into the picture. Can we call the wavefuncion real? Does it collapse at a measurement?
No one knows, and if you have a book that tells you it does, throw it away please.
 
  • #10
Pjpic said:
What are the top theories as to why particles show the interference pattern in the double slit experiment.

I have to agree with malawi_glenn in this instance, that QFT is the best description, in that it predicts the interference pattern given the energies of the particles involved.

As to *why* they interfere, no-one knows. But no-one knows why objects fall to the ground when left to their own devices. We can explain it well with theory and even predict quite a lot about *how* they will behave. But not why.

In this specific instance, I think you'll be looking at the path integral formulation. I'm not sure what your level of maths is, but if you don't know what a functional integral is, look up the Douglas Robb memorial lectures where a clever guy gave an overview of QED for the layperson. It's really quite easy to follow and doesn't mislead at all to my knowledge. Anything you learn will not have to be unlearned later.
 
  • #11
These type of why questions aren't really answerable. It's the same as asking 'Why are there electrons?'. In the abscence of available answers, think about it and reach your own conclusion.
 

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