Does the Doppler Effect Double the Color Shift of a Moving Light Source?

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Discussion Overview

The discussion revolves around the Doppler effect and its implications for color shift when a light source moves towards a colored object at high speeds. Participants explore whether the color shift would be doubled, considering different theoretical perspectives and the application of the Doppler equation.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that the color shift due to the Doppler effect could be doubled, while another proposes that the Doppler equation might be applied twice, leading to a compounded effect.
  • Another participant clarifies that the point of observation should be from the light source itself, such as in the case of a car with headlights.
  • A different viewpoint indicates that when shining white light at a red object, the reflected light will primarily consist of red wavelengths, and the Doppler shift will not significantly alter the intensity of the red light observed.
  • There is a mention of the difference in Doppler shifts observed in police radar, which uses a pure frequency, suggesting that the context of measurement affects the interpretation of the Doppler effect.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the color shift is doubled or how the Doppler effect applies in this scenario. Multiple competing views remain regarding the application of the Doppler equation and the nature of the observed color shift.

Contextual Notes

There are unresolved assumptions regarding the conditions under which the Doppler effect is analyzed, particularly concerning the reference frame of the observer and the nature of the light source.

691175002
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I am having a friendly argument with a friend.
If a light source was moving towards a colored object at high speeds in a completely dark area, would the color shift due to the Doppler effect be doubled?

Possible theories are no (which we agree is wrong)
Yes (which may be right)
Or simply that the Doppler equation is applied twice, the second time on the result of the first equation. (Most probbable).

Thanks.
 
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691175002 said:
I am having a friendly argument with a friend.
If a light source was moving towards a colored object at high speeds in a completely dark area, would the color shift due to the Doppler effect be doubled?

Possible theories are no (which we agree is wrong)

... that's one hellava argument against democracy if I ever heard one.

Yes (which may be right)
Or simply that the Doppler equation is applied twice, the second time on the result of the first equation. (Most probbable).

Thanks.
 
Sorry, I misworded the question, The point of observation is supposed to be from the light source. (such as a car with headlights).
 
If you shine white headbeam light at a red object, the returning light contains mostly red wavelengths, because those are the wavelengths reflected. The Doppler shift in the incident light will still leave about as much intensity in the red. Thus the light reflected back toward you will be the same as if you had been at rest. The only Doppler you will observe will be the relativistic Doppler shift for your movement toward the red object.
The Doppler shift for police radar is different, because they use a relatively pure frequency, so you can't use this in court.
 

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