Theoretical Limit on Frequency?

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Discussion Overview

The discussion revolves around the theoretical limits on the frequency and wavelength of electromagnetic (EM) waves. Participants explore concepts related to energy, the implications of high frequencies, and the boundaries of current physical theories.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants propose that frequency is continuous and has no upper or lower bound, suggesting that there is no finite limit on the possible energy of a photon.
  • Others argue that frequencies higher than the inverse Planck time or wavelengths smaller than the Planck length may not be meaningful within current theories.
  • One participant notes that while there may be practical limits on creating high-energy photons, this does not imply a definitive theoretical limit.
  • Concerns are raised about the implications of a frequency limit on the Doppler effect, questioning whether such a limit would contradict established physics.
  • Some participants discuss the idea that extreme frequencies could necessitate modifications to special relativity, particularly regarding energy and length scales at the Planck level.
  • There is a claim that high-energy photons could transform into different types of bosons, although this is challenged by another participant who argues that energy is frame-dependent.
  • Infinities in physics are mentioned as problematic, with participants reflecting on the implications of infinite frequencies in photon-photon collisions.

Areas of Agreement / Disagreement

Participants express a range of views, with no consensus on whether there is a theoretical limit on frequency or wavelength. Disagreements exist regarding the implications of high frequencies and the validity of current physical theories at extreme energy levels.

Contextual Notes

Some discussions hinge on the limitations of current theories at high energies and the assumptions underlying the Doppler effect. The conversation also touches on the complexities of frame dependence in particle physics.

Swapnil
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Is there is theoretical limit on how large a frequency (or how small a wavelength) an EM wave can have?
 
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the frequency available is continuous and has no upper or lower bound, so there is no finite lower limit or upper limit on the possible energy of a photon. On the upper side, there are practical limits because you have limited mechanisms for creating really high energy photons. Low energy photons abound, but when you get below radio frequencies, the photon energies are so tiny compared to room temperature thermal energy that you really never see them as distinct quantized entities - they are swamped in the background.
 
Last edited:
Swapnil said:
Is there is theoretical limit on how large a frequency (or how small a wavelength) an EM wave can have?
No...
 
Swapnil said:
Is there is theoretical limit on how large a frequency (or how small a wavelength) an EM wave can have?

unfortunately, many of the physical theories we have are strictly valid at a relatively low energy... since freq is related to energy... so you may have problems when things go extremely large... but that doesn't mean there is definitely a limit..it is just a statement saying that we don't know ..yet
 
If there is a limit then either the Doppler's shift is completely wrong for ultra high frequency or there is a bound (less than c) on how fast one can travel with respect to a source of a light.
 
actually if you pump enough energy into a photon it will entually become a different kind of boson, I forgot the particulars however.
 
tim_lou said:
If there is a limit then either the Doppler's shift is completely wrong for ultra high frequency or there is a bound (less than c) on how fast one can travel with respect to a source of a light.
How can you draw this conclusion?
 
in Doppler's effect, the frequency goes to infinity as one approaches a light source close to the speed of light... so if there is a limit on how high frequency goes and Doppler's effect is correct, then there is limit (lower than c) on how fast one can travel toward a light source. similarly, if there is a lower bound on frequency, then there is a limit (lower than c) on how fast one can travel away from a light source.
 
  • #10
That is correct, invariance of the Planck energy scale could require at least a modification of special relativity so that blueshifting is only possible asymptotically up to Planck energy (or so that Planck length may not be Lorentz-contracted into a smaller length, etc). At worst, special relativity could break completely at this scale.
 
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  • #11
tim_lou said:
in Doppler's effect, the frequency goes to infinity as one approaches a light source close to the speed of light... so if there is a limit on how high frequency goes and Doppler's effect is correct, then there is limit (lower than c) on how fast one can travel toward a light source. similarly, if there is a lower bound on frequency, then there is a limit (lower than c) on how fast one can travel away from a light source.
So what happens in a photon-photon collision? There should be infinite frequencys involved?
 
  • #12
lightarrow:
Infinities are very frequently :smile: serious problems in physics.
 
  • #13
CPL.Luke said:
actually if you pump enough energy into a photon it will entually become a different kind of boson, I forgot the particulars however.

This doesn't sound correct. No matter how great the energy of a photon is, there is always another frame, where the energy is arbitrarily small. If a photon could change into another particle, it should not depend on the chosen frame.
 
  • #14
tehno said:
lightarrow:
Infinities are very frequently :smile: serious problems in physics.
Certainly. I didn't mean that tim_lou's conclusion have to be wrong, I know doppler effect equation and how it works. Mine was just a question.
Of course I know that a reference frame where a photon is stationary doesn't exist, but what he said makes one think! it's an interesting consideration!

(Nice the joke with "frequently"!)
 

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