"Light is wave-like and particle-like" --- Why this is wrong?

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    Duality of light
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Discussion Overview

The discussion revolves around the characterization of light as having both "wave-like" and "particle-like" properties. Participants explore the implications of this duality, questioning the accuracy of these descriptions and their effectiveness in conveying quantum mechanics to a lay audience. The conversation touches on theoretical interpretations, conceptual clarity, and the nature of quantum objects.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants argue that describing light as having both wave-like and particle-like properties is misleading, suggesting instead that light is a real wave and has particle-like attributes due to the lack of rest mass in photons.
  • Others propose that the duality of light should be explained differently to avoid creating a false symmetry between wave and particle descriptions.
  • One viewpoint emphasizes that light behaves as a particle when interacting with matter and as a wave when propagating through space, suggesting a transformation between these states.
  • A later reply questions the assumption that quantum entities possess properties in the conventional sense, indicating a need for careful consideration of terms like "contact with matter."
  • Some participants suggest that quantum objects should not be strictly classified as waves or particles, but rather as entities whose behavior resembles classical descriptions depending on the context.
  • Concerns are raised about the potential for misunderstanding among lay audiences due to the metaphorical language often used to describe quantum phenomena.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of light and its duality. There is no consensus on the best way to describe light's properties or the implications of its behavior in quantum mechanics.

Contextual Notes

Participants note that the discussion may lack a comprehensive understanding of existing theories and research related to light, suggesting that new ideas should be grounded in established work.

DavidReishi
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It's often said that light has both "wave-like" and "particle-like" properties, that light is both "wave-like" and "particle-like." But such a concept is fundamentally out of sync with reality. For, while it's true that light exhibits "particle-like" properties, the same cannot be said about "wave-like" properties. Real waves aren't "wave-like" any more than a real duck is a manifestation of being "duck-like." "Particle-like?" Yes, because photons have no rest mass. "Wave-like?" Uh, no, it's a real wave.

Conceptually, the more correct thing to say is that light has both particle-like and wave properties. Symmetry shouldn't be artificially inserted.
 
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DavidReishi said:
Yes, because photons have no rest mass.
The description is not limited to light, everything can look "wave-like" and "particle-like".
DavidReishi said:
"Wave-like?" Uh, no, it's a real wave.
With a wave you cannot describe the photo-effect, for example.

All those things are attempts to describe quantum mechanics to a lay audience. They are not the actual physics, which deals with quantum objects in a purely quantummechanical way.
 
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mfb said:
The description is not limited to light, everything can look "wave-like" and "particle-like".

Okay, but I think you're missing the point. When evidence exists of light as a wave, e.g. the double-slit experiment, we're not talking about wave-like movement. We're talking about real wave movement. But when evidence exists of light "as a particle," the opposite is the case. We're not talking about a real particle, since real particles have rest mass. We're talking about particle-like attributes.

With a wave you cannot describe the photo-effect, for example.

And what? All that means is that light is in a particle-like form whenever it's being either emitted or absorbed by matter.

All those things are attempts to describe quantum mechanics to a lay audience. They are not the actual physics, which deals with quantum objects in a purely quantummechanical way.

Then physicists should change the way they attempt to explain the duality of light to lay audiences. Because to suggest that light has both "wave-like and particle-like" properties is inaccurate and misleading. It presents the problem as symmetrical, when it isn't. And in doing so it creates a problem where one doesn't exist.

Light is in a particle-like form when it's in contact with matter, and is a wave when it's in movement between particles of matter. What's so hard about that?
 
DavidReishi said:
...and in doing so it creates a problem where one doesn't exist.

Light is in a particle-like form when it's in contact with matter, and is a wave when it's in movement between particles of matter. What's so hard about that?

You are supposing properties and attributes "that don't exist"... just "contact with matter" needs lots of attention.
Someone will come in shortly to mention that quantum entities don't have properties or attributes in the "usual" way.
 
bahamagreen said:
... just "contact with matter" needs lots of attention.

Well we know that when light interacts with matter, it's either emitted from the matter or absorbed by the matter. So how 'bout this:

Light is in a particle-like form in its emission from matter, upon which it transforms into a wave in its movement from the matter, and back again into its particle-like form in its absorption back into matter.
 
Perhaps it's best to say that quantum objects are neither waves nor particles.
They are quantum objects whose behaviour *resembles* classical waves or particles depending on the situation.
 
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DavidReishi said:
Then physicists should change the way they attempt to explain the duality of light to lay audiences.

Good point.
 
Human brains are good at using metaphor and simile too describe something that otherwise doesn't make sense. Or to fill in missing pieces of an observation. Don't know if that's a good thing or a bad thing. Maybe the quote, "You can't handle the truth!" from I-forget-the-movie explains this phenomenon. I've always wondered if other animals do this.
 
rootone said:
Perhaps it's best to say that quantum objects are neither waves nor particles.
They are quantum objects whose behaviour *resembles* classical waves or particles depending on the situation.

I think you're falling into the trap of the false symmetry. While manifestations of light resemble classical waves, they never resemble classical particles...because classical particles have rest mass. When light is demonstrated to be in a wave-form, it's not a flawed wave-form. As far as we can tell, it's simply a wave-form as we know waves. But whenever light is demonstrated to be in a "particle-form," it is an inherently and fundamentally flawed particle-form because it has no rest mass.

The false symmetry expressed in your words is part of the reason why people in general, physicists included, overlook the simple solution to the "duality of the theory of light." Namely, that it's light itself that has the dual nature, not in some mysterious way, but simply in that light transforms from one form into the other. It commences its existence being emitted from matter in a particle-like form (a photon), then it transforms into a wave and moves, and then finally it is transformed again into the same particle-like-form (an identical photon to the first) as it is absorbed into matter. Upon which its existence is at an end.

(BTW, this simple solution to the problem of the dual theories of light is supported, so far, by the double-slit experiment, the photoelectric effect, low-light CCD experiments, and the fuzzy-shadow-edge effect of light.)
 
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