Does light exist between events?

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Discussion Overview

The discussion revolves around the question of whether light exists between events, particularly in the context of quantum mechanics (QM). Participants explore the implications of this question on the understanding of photons, their trajectories, and the philosophical aspects of observation in physics.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Philosophical inquiry

Main Points Raised

  • Some participants propose that the existence of light (photons) between events could resolve paradoxes in quantum mechanics, questioning the viability of this perspective.
  • Others argue that while there is theoretical evidence for light as electromagnetic waves, the existence of photons in flight cannot be empirically proven without observation, citing conservation laws as indirect support.
  • A participant notes that describing photon activity when unobserved is problematic and references existing experiments that address this issue.
  • One participant emphasizes that the question of what happens when not observed is more philosophical than scientific, suggesting that it leads to sterile speculation.
  • Another participant humorously asserts that their potato chips will not turn into anything else, reinforcing the empirical nature of observations.
  • A later reply suggests that the discussion has reached a point where further speculation may not be productive.

Areas of Agreement / Disagreement

Participants express differing views on the nature of light and photons, with some emphasizing the philosophical implications and others focusing on empirical evidence. The discussion remains unresolved, with multiple competing perspectives present.

Contextual Notes

Participants highlight limitations in proving the existence of phenomena without observation and the challenges in discussing unobservable properties of photons. There is also mention of the lack of a position operator for photons, which complicates the discussion.

bremsstrahlung
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Does light exist between events? [mod: unapproved source]

The above perspective will resolve a lot of paradoxes in QM. Is the above view viable or is it untenable?

Are there any evidence to show that photons exist in flight? Are there any evidence of photon trajectories?
 
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This is an empty question. You cannot prove the existence of anything without looking at it, and detecting light is an event (i.e., an observable fact). Of course, there is ample theoretical evidence for the fact that light (electromagnetic waves with typical wavelenths in the range our eyes are sensitive too, i.e., about 400-800nm) is there even if it's not detected. The reason are the conservation laws. For light that's energy, momentum, and angular momentum. According to QED, the best theory we have about the behavior of electromagnetic waves and their interaction with electrically charged matter, all these quantities are conserved, and that's why it's strong evidence that there is something, namely the electromagnetic wave, even if it's not interacting with a detector and observed by us. From a strictly empirical perspective, that's however no proof, but since QED is so good in describing everything observable it's hard to imagine that it's too wrong about what's not observable.
 
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@bremsstrahlung your source does not meet our guidelines. Please provide one that does or this thread will be closed.
 
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bremsstrahlung said:
Does light exist between events? [mod: unapproved source]

The above perspective will resolve a lot of paradoxes in QM. Is the above view viable or is it untenable?

Are there any evidence to show that photons exist in flight? Are there any evidence of photon trajectories?

As Greg mentions, the reference is unsuitable. As to the assertion that the reference resolves any paradoxes in QM, that is quite a stretch. I would call it hand waving (and that is being kind).

The fact is: it is already generally accepted that trying to describe the activity of photons when NOT being observed is problematic. There are experiments around that concept already. Also: our PF member A. Neumaier has pointed out that the photon lacks a position operator:

http://arnold-neumaier.at/physfaq/topics/position.html

So your speculation on the point is misplaced. What is relevant is the ability to explain what is likely to be seen in various experiments. In a powerful demonstration that photons do in fact represent discrete packets:

http://people.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf

If you would like to read up on the usage of the word "photon" and how that fits into QT, along with some investigation into light's unobservable properties:

http://aporia.byu.edu/pdfs/manchak-arguments_concerning_photon_concepts.pdf
 
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This problem has nothing to do with photons per se. "What can we say is happening when we are not watching it" is a question that is more philosophical than scientific, and it's a sterile philosophy. It may well be that the potato chips in the bag turn into tiny dancing pink unicorns when they are on the shelf, provided nobody is looking at them (or otherwise measuring things). Nobody can prove it's happening. Nobody can prove it's not. But it's hardly good science.
 
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My potato chips have no chance to turn into anything else than some mash in my stomach. That's an empirical fact!
 
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I think a lot of good responses have been given so we will close this speculation out.
 
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