Is the Planck Wavelength the Smallest Possible Measurement in Physics?

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    Planck Wavelength
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Discussion Overview

The discussion centers around the concept of whether there exists a smallest possible wavelength in physics, specifically considering the implications of the Planck length. Participants explore the meaning and significance of wavelengths below this scale, touching on theoretical frameworks and the limitations of current physics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose rephrasing the question to focus on "meaningful" wavelengths, suggesting that the Planck length is the smallest meaningful wavelength.
  • Others argue that anything below the Planck length becomes practically meaningless and indescribable according to current theories.
  • A later reply introduces the idea that while the Planck length is significant, future theories may need to address phenomena in the sub-Planckian realm.
  • Some participants express uncertainty about the existence of anything smaller than the Planck length, noting that if such entities exist, they cannot be described by current theories like General Relativity or Quantum Mechanics.
  • One participant presents a theoretical argument linking the Compton wavelength and Schwarzschild radius to derive the Planck length, suggesting that ordinary physics breaks down at this scale.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence or significance of wavelengths smaller than the Planck length, with multiple competing views remaining regarding the implications of such scales.

Contextual Notes

The discussion highlights limitations in current theoretical frameworks and the potential need for new theories to describe phenomena at or below the Planck length. There is an acknowledgment of unresolved mathematical relationships and definitions related to these concepts.

ryan albery
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It there a smallest possible wavelength? And if there is, what is that wavelength?
 
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You should rephrase your question to:
"Is there a smallest possible meaningful wavelength?"
Yes, the Planck length would be. Anything below Planck length isn't meaningful. Things become practically pointless after Planck length, indescribable, dimensionless, etc.
 
Fuzzystuff said:
You should rephrase your question to:
"Is there a smallest possible meaningful wavelength?"
Yes, the Planck length would be. Anything below Planck length isn't meaningful. Things become practically pointless after Planck length, indescribable, dimensionless, etc.

With the caveat that this is true for current theories. One of the points of unification or a new theory would be to describe the sub-Planckian realm.
 
I'm don't think I follow... is there anything smaller than a Planck length?
 
ryan albery said:
I'm don't think I follow... is there anything smaller than a Planck length?

If there is, it is not describable by current theories. Whatever that is, cannot be described by GR, QM, and so forth.
 
The following argument may be wrong, but it explains why everybody believes that at the Planck scale ordinary physics breaks down.

Consider a particle with a Compton wave length; this length describes somehow its localization. Consider the gravitation of that particle and its Schwarzschild radius. Now assume that its Compton wave length becomes smaller than its Schwarzschild radius. The particle (according to classical GR) would collaps into a black hole.

If you now set Compton wave length = Schwarzschild radius and solve the equation you will get the Planck length.
 

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