Concerning QED and the Many Worlds theory.

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Discussion Overview

The discussion revolves around the relationship between Quantum Electrodynamics (QED) and the Many Worlds Interpretation (MWI) of quantum mechanics. Participants explore the implications of QED's mathematical framework and its analogy to the concept of multiple universes, examining the nature of photon behavior and the interpretation of quantum mechanics.

Discussion Character

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

Main Points Raised

  • Some participants suggest that in QED, a photon takes all possible paths, with most paths cancelling out, leaving the observed path.
  • Others argue that the interpretation of photons taking all paths is a significant leap and that the mathematics allows for descriptions where photons take no path at all.
  • There is a proposal that the Many Worlds Interpretation can be viewed as a vast number of concurrent universes, but this is contested regarding how these universes interact mathematically.
  • One participant notes that the concept of 10^500 possible universes is often associated with String Theory rather than quantum mechanics, suggesting a need for clarity on the source of this assertion.
  • Another participant emphasizes the importance of understanding the MWI before using it as a basis for further speculation about the multiverse.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of QED and its implications for the Many Worlds theory. There is no consensus on the accuracy of the analogy between photon paths and the existence of multiple universes, nor on the validity of the 10^500 universes claim in relation to quantum mechanics.

Contextual Notes

Some statements rely on interpretations of mathematical frameworks that may not be universally accepted. The discussion includes speculative reasoning and personal theories, which may not align with established scientific consensus.

John Plant
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In QED the maths suggests that a photon takes all possible paths, and all but one of the paths cancel out leaving the path we observe.
Using this as an analogy:-
The maths of quantum mechanics suggests a vast number of possible universes concurrent with our universe.
Perhaps all these mathematically possible universe cancels out with the others, leaving what we see as the wave function of our universe.

Has anyone thought along these lines?
 
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John Plant said:
In QED the maths suggests that a photon takes all possible paths, and all but one of the paths cancel out leaving the path we observe.
Not quite... It says that the probability of the photon being detected at a particular point in time and space can be calculated by adding up the amplitudes associated with all possible paths to that point. The leap from that calculation to "the photon takes all possible paths" is large and not easily justified; and the fact that I can just as accurately describe what the math says by saying "the photon takes no path" suggests that neither "all paths" nor "no path" are very good mental models.
The maths of quantum mechanics suggests a vast number of possible universes concurrent with our universe.
Perhaps all these mathematically possible universe cancels out with the others, leaving what we see as the wave function of our universe.
It is possible to describe the Multiple Worlds interpretation of quantum mechanics as "a vast number of possible universes concurrent with our universe" (athough that's not really what the math says, it's just a not very good English language substitute for what the math says). But even if we try following that line of thought, the mathematical terms in the wave function that correspond to the different "universes" don't cancel - they add in such a way that they don't affect one another, and that property is essential to the operation of the MWI.
Has anyone thought along these lines?
Well, yes, you just did :)
But seriously, kidding aside, reasoning based on analogy doesn't generally go very far in quantum mechanics. An analogy explains something by showing how it works similarly to something that is already understood - but QM doesn't work the way the classical world does, so we don't have a pool of already understood concepts to analogize from.

(This might be a good time to remind everyone of the PF policy on speculation and personal theories... This thread is close to the edge)
 
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John Plant said:
In QED the maths suggests that a photon takes all possible paths, and all but one of the paths cancel out leaving the path we observe.
Using this as an analogy:-
The maths of quantum mechanics suggests a vast number of possible universes concurrent with our universe.
Perhaps all these mathematically possible universe cancels out with the others, leaving what we see as the wave function of our universe.

Has anyone thought along these lines?

I would say that your summary of QED is not correct, to start with. Yes, you can describe the mathematics of QED in terms of amplitudes associated with various possibilities, and you get cancellation between different alternatives. But it's not true that the result of the interference only leaves one possibility.
 
The Mathematics of quantum mechanics suggests the 10^500 possible universe. I don't think the reality of these universes is suggested any further than this- I am not aware of any further description of any other universe, other than creative speculation.
I just think it's interesting that maybe all the universes are present as potential realities and what we see as our universe is all these potential universes resolved into our 'reality'.either by cancelling out ,reinforcing or both or something else perhaps.
I simplified my reading of QED as a photon taking all paths and cancelling out leaving the path of shortest distance. Did the photon take all possible paths- who really knows- but the maths says this is a good way to look at how a photon behaves. This was used to explain the origin of my thought and to help describe my imaginings on the multiverse.
 
John Plant said:
The Mathematics of quantum mechanics suggests the 10^500 possible universe.

As I understand things this number is usually associated with String Theory Landscapes not QM.

Cheers
 
John Plant said:
The Mathematics of quantum mechanics suggests the 10^500 possible universe.
You will have to provide some acceptable source for this assertion - that will mean a peer-reviewed paper or citation of an accepted textbook.

This was used to explain the origin of my thought and to help describe my imaginings on the multiverse.
If you're going to use the multiverse as the starting point for your imagining, you'll want to be reasonably confident in your understanding of the MWI first. https://www-tc.pbs.org/wgbh/nova/manyworlds/pdf/dissertation.pdf, Everett's 1956 dissertation, would be a good start.
 
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