Standard Compton Effect Explained Classically/Semiclassically

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Discussion Overview

The discussion revolves around the possibility of explaining the standard Compton effect using classical or semiclassical approaches. Participants explore the definitions, implications, and limitations of such explanations, touching on both theoretical and conceptual aspects.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants propose that the standard Compton effect can be explained semiclassically, using quantum theory for matter and classical fields for electromagnetism.
  • Others question the definition of the "standard Compton effect" and seek clarification on what constitutes the "effect" in this context.
  • One participant suggests that the shift in wavelength is the key aspect of the Compton effect, referencing high-school physics treatments that assume classical relativistic particles.
  • There is a contention that explaining the Compton effect requires a definition of a photon, which cannot be achieved without understanding the quantization of the electromagnetic field.
  • Some participants assert that a classical explanation cannot be achieved, emphasizing the limitations of classical treatments in capturing the phenomenon.
  • A participant mentions the momentum loss of radiation in a diluted plasma context, noting that there is no momentum transmitted from a linearly polarized electromagnetic field to an electron.
  • References to literature are made, suggesting that classical treatments exist but may not align with the conventional understanding of photons.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of a classical or semiclassical explanation of the Compton effect. There is no consensus on whether such explanations can adequately capture the phenomenon, with multiple competing perspectives presented.

Contextual Notes

Some limitations are noted, including the dependence on definitions of photons and the unresolved nature of classical versus quantum explanations. The discussion reflects a range of assumptions and interpretations regarding the Compton effect.

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I know this topic has already been covered many times, but, is it possible to explain classically or semiclassicaly the standard Compton effect?
 
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I remember reading once in some Quantum optics text that the standard Compton effect (together with the simplest form of the photoelectric effect) can indeed be explained semiclassically, i.e using quantum theory for matter and classical fields for EM. This was of course not recognised at the time though.

Don't remember the details or where I read it unfortunately :(
 
lightarrow said:
I know this topic has already been covered many times, but, is it possible to explain classically or semiclassicaly the standard Compton effect?

What is the standard definition of the "standard Compton effect" ? I mean, what is the "effect" in the "Compton effect" ?

Daniel.
 
dextercioby said:
What is the standard definition of the "standard Compton effect" ? I mean, what is the "effect" in the "Compton effect" ?

Daniel.

[tex]\lambda\prime-\lambda=\frac{h}{m_ec}(1-cos\theta)[/tex]

With "standard" I mean without considering the electron's spin.
 
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Okay, then, so it's the shift in wavelength. IIRC, in high-school physics the treatment is semiclassical, or almost classical: the electron & the photon are assumed classical relativistic particles (i.e. always on their mass-sheet) and then E=h\nu for the photon is used and the shift is calculated imposing conservation of energy and momentum.

But to get back on topic, explaining the effect would require explaining what a photon is: and that can't be done without doing/knowing the quantization procedure for the em field. As for the quantized electron field, it's useless to think of the classical electron interacting with the quantized em field, so

The question's answer's "no".

Daniel.
 
Sorry, I didn't explain well. I intended with light treated as a classical EM field.
 
I have been thinking about this lately in the context of momentum loss of radiation upon passage through a diluted plasma. Momentum loss from stationary plasma should red-shift radiation. I found that there is no momentum transmitted from radiation field to electron if the em field is linearly polarised.

[OOOPS! I apologize. In replying to your post, I accidentally hit "edit" instead of "quote" and permanently edited your post. I can't seem to get the buffer to repost your entire original message. Oy! - Zz]
 
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dextercioby said:
It can't be done.

Daniel.

So, what did they talk about?:

http://www.usenet.com/newsgroups/sci.astro/msg02581.html:
(Edit: this url doesn't work anylonger, at least from my server.)
Quote:
<<You should take a look at
"Atoms and light" by John N. Dodd (Plenum Press, New York, 1991).

In Chapter 6, the Compton scattering is treated in an entirely
classical way, without using energy and momentum conservation,
but just standard classical em + relativistic *kinematics*,
by the picture of a circularly polarized em wave impinging upon
a charged particle.
The calculation is based on deriving a steady-state solution
for the down-stream motion of the particle which is superimposed
to the constant rotation at the frequency of the passing wave.
I haven't read the analysis in detail, but my first impression
is that it is quite clever.

It is, especially in light of the comments at page 55, apparent
that the standard Compton effect, i.e. the one the Compton
explained using the notion of photon, does not actually *need*
this notion.
So, according to the author, the standard (spin-free) Compton
effect cannot be invoked to argue the existence of photons. >>

Unfortunately I don't have that book, so I can't make any comment.

Or: http://adsabs.harvard.edu/abs/1979PhDT...96B
Quote:
<<The Compton effect is given a classical explanation which yields the Klein-Nishina cross section and demonstrates the classical origin of photon-like behavior of the incident and scattered radiation>>.

Or: http://www.springerlink.com/content/r10am90am8v1a18p/
 
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