Do photons of all energies exist?

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Discussion Overview

The discussion revolves around the existence of photons of all energies, particularly in the context of quantum systems that can vibrate in discrete energy levels. Participants explore the implications of discrete versus continuous energy levels, the generation of electromagnetic radiation, and the relationship between frequency and energy in various systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that while bound electrons have discrete energy levels, light can be generated through other means, suggesting that all frequencies are possible.
  • One participant argues that shaking a clump of electrons can generate a range of frequencies of light, indicating that the method of generation is not limited to atomic transitions.
  • A question is raised about whether there is a maximum frequency for electromagnetic waves produced by shaking electrons, with a suggestion that increased shaking leads to higher emitted frequencies.
  • Another participant speculates that the "hotness" of a system could approach infinity as the shaking approaches the speed of light.
  • Concerns are expressed regarding the link between the acceleration of electric charges and the frequency of the electromagnetic waves produced, with references to classical electromagnetism concepts.
  • A participant challenges the premise that all quantum systems vibrate in discrete energies, noting that some systems, particularly free systems, do not have discrete energy levels.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between discrete energy levels and the existence of photons of all energies. There is no consensus on whether all frequencies can exist or if there are limitations based on the nature of the quantum systems involved.

Contextual Notes

Some claims depend on the definitions of quantum systems and their energy levels, and there are unresolved questions regarding the maximum frequency of emitted electromagnetic radiation and the implications of shaking electrons at high speeds.

Vibin Narayanan
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If a quantum sistem can vibrate only in discreate energies, can there exist photons of all energies (All frequencies in the real number line)?
 
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Vibin Narayanan said:
If a quantum sistem can vibrate only in discreate energies, can there exist photons of all energies (All frequencies in the real number line)?

:welcome:

The short version is yes, all frequencies are possible. The energy levels of bound electrons are discrete, true, but light can be generated in other ways.
 
Vibin Narayanan said:
If a quantum sistem can vibrate only in discreate energies, can there exist photons of all energies (All frequencies in the real number line)?

I can take a clump of electrons, and shake it real fast up and down. Voila! I've just generated EM radiation/light of a certain frequency. What is to prevent me from having a large range of frequency of light by doing that?

If you think this is not realistic, look up how the various EM radiation are created at synchrotron light source. You need to expand your understanding of how light is created here. It is NOT just simply via atomic transition.

Zz.
 
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Vibin Narayanan said:
If a quantum sistem can vibrate only in discreate energies, can there exist photons of all energies (All frequencies in the real number line)?
Sure, that's like asking how can the real line be made of discrete points.
 
Is there a maximum number to the wave frequency in this system?
 
Leonardo Machado said:
Is there a maximum number to the wave frequency in this system?
The harder you shake it, the hotter it is. The hotter it is, the more energetic the emitted electromagnetic radiation, and the higher the frequency.
 
Would there be a limit to how fast you could shake it?
 
I think the "hotness" would approach infinity as the "shaking" would approach c.
 
I'm aware that accelerating electric charges produce EM waves. But, how is this acceleration linked with frequency of wave produced?
 
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Vibin Narayanan said:
I'm aware that accelerating electric charges produce EM waves. But, how is this acceleration linked with frequency of wave produced?
It's a bit perplexing that you're asking this question in an I-level thread, as you should have seen the answer around the end of your first undergraduate year when you studied introductory E&M... And if you haven't already studied introductory E&M you would be marking your threads "B" instead of "I".

But even if you haven't looked at classical E&M yet, there is an intuitive way of thinking about the situation. Consider a charged particle that is oscillating, accelerating back and forth. How does the electric field at some distance from the particle change? Coulonb's law, which you will have seen in high school, says that the field is pointing towards the particle, so if the particle is moving back and forth with a particular frequency, the electric field must be swinging back and forth with the same frequency as it tried to keep up. It's analogous to what happens if you place the palm of your hand flat on the surface of a body of water and then accelerate your hand up and down - there will be waves in the water, and of course their frequency will match the frequency of your hand movements.

WARNING WARNING WARNING The paragraph above is a terrible oversimplification, suitable only for helping someone who is not serious about understanding what's really going on. This picture only works for the particular case of a charged particle oscillating back and forth, and only if you are willing to accept all sorts of oversimplifications. To understand what's really going on, you should work through the last chapter or so of Purcell or other first-year E&M textbook.
 
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  • #11
Vibin Narayanan said:
If a quantum sistem can vibrate only in discreate energies

You are starting from a mistaken premise. Some quantum systems have discrete energy levels, but some don't. Briefly (and heuristically), bound systems have discrete energy levels and free systems do not.
 
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