Is There a Maximum Wavelength for Electromagnetic Radiation?

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Discussion Overview

The discussion revolves around the question of whether there is a maximum wavelength for electromagnetic radiation, exploring theoretical limits, implications of the universe's size, and the relationship between frequency and energy in both classical and quantum contexts.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant questions if Maxwell's equations establish a maximum wavelength, suggesting that the size of the universe might impose limits on detection.
  • Another participant asserts that there is no constraint on how low the frequency can get, while acknowledging that some theories propose upper limits.
  • A participant discusses the classical perspective, noting that the longest electromagnetic wave corresponds to a static electric field, indicating no classical limit on how slowly it can move.
  • Another contribution highlights that, according to several sources, photons can have arbitrarily small energy due to their lack of rest mass, implying no lower limit on frequency.

Areas of Agreement / Disagreement

Participants express differing views on the existence of limits on frequency and wavelength, with no consensus reached on whether a maximum wavelength exists or the implications of the universe's size.

Contextual Notes

Participants mention the influence of boundary conditions and cosmological factors on the properties of wavelengths comparable to the universe, indicating potential limitations in understanding these phenomena.

tomwilliam
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Is there any lower limit on the frequency of electromagnetic radiation? I imagine that beyond a certain frequency it becomes impossible to detect, but is there anything in the maxwell equations that establishes a maximum wavelength (besides the limits of the size of the universe)?
Thanks
 
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I'm pretty sure there isn't any constraint on how low the frequency can get, numerous theories do make some upper limits though.

As an aside, I'm not sure what effect even the finite size of the universe would have because of weird boundary conditions, and other cosmology stuff... I don't think any theory could accurately tell you the properties/details of wavelengths comparable to that of the universe; can anybody affirm/deny that?
 
Classically, the longest EM wave simply corresponds to a static electric field, such as point charge that is fixed in space. There is no classical limit to how slowly you can make it move (a body at rest tends to stay at rest).

Considering quantum theory and the uncertainty of known energy though, the answer is less obvious.
 
Several "popular" and more technical books I've read point out that there is no lower limit. The photon can have arbitrarily small energy, which means that the symmetry it embodies is perfect and unbroken. Because the photon has no rest mass, it can have an arbitrarily small energy.
 

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