Help with understanding the Doppler effect

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Discussion Overview

The discussion revolves around understanding the Doppler effect, focusing on the properties of waves and how their characteristics change due to the relative motion of the observer and the source. The conversation includes theoretical modeling and mathematical reasoning related to wave propagation, frequency, and wavelength in different frames of reference.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that events such as wave production are invariant across reference frames, using the example of a falling brick splitting into two pieces.
  • The historical context of the Doppler effect is introduced, noting its discovery by Christian Andreas Doppler in 1842.
  • A model is proposed involving a source of waves and an observer, with a focus on how the motion of the source affects the wave characteristics.
  • The participant describes a mathematical representation of wave properties, including amplitude, wavelength, and frequency, and how these change with the motion of the source relative to the observer.
  • It is noted that the wavelength decreases when the source moves towards the observer and increases when moving away, leading to changes in frequency.
  • Mathematical relationships are presented to describe how frequency and wavelength are affected by the relative velocities of the source and observer.

Areas of Agreement / Disagreement

Participants express various perspectives on the Doppler effect and its implications, but no consensus is reached regarding the interpretations of the mathematical models or the implications of the effect itself.

Contextual Notes

The discussion includes complex mathematical formulations and assumptions about wave behavior that may not be fully resolved, particularly regarding the implications of different reference frames and the nature of wave propagation.

  • #61
Ibix said:
I get the impression you are trying to imply that I'm stupid for not following your argument. Am I correct?
You are again incorrect, I am saying we have reach the crucial point the investigation of which will decide who is more close to reality!
Ibix said:
No it is not. It's an extended period of time.

...and it happens the same whether you regard the source as moving with respect to the medium or the medium with respect to the source. Proof:

Let the source emit waves of period T and speed c. The medium is stationary and the source moves in the same direction as the waves at speed v. When the second wave crest is emitted, the first wave crest has traveled ##cT## and the source has moved ##vT##. Thus the wavelength is ##(c-v)T##.

Now again, but this time we regard the source as stationary and the medium as moving at speed ##-v## (i.e., we've subtracted ##v## from the speed of both medium and source). When the second wave crest is emitted, the first has traveled ##(c-v)T## and the source has not moved. Thus the wavelength is ##(c-v)T##.

No difference.
I will better make a picture, one moment. Just go to the outside of the house for a sec...
 
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  • #62
frostysh said:
I will better make a picture
It will not make a difference. An honest picture must obey the maths I just laid out.
 
  • #63
Ibix said:
It will not make a difference.
Well actually you are saying truth about the similarity of the cases! Wery many thanks! You the first which helped to understand, on other forum me get topic deleted! The was my mistake... Very good, know I can continue the studies. This forum is indeed useful!

Again many-many thanks!
 
  • #64
Dale said:
Best not since he is generally right.

By the way, I am not sure if you missed this post of mine above:
The classical mechanics is good description of realitity too, and there is no reason to give any connections to the non-classical theories, it's just specualtions and play with words. Anyway I have understand my mistake, which was obvious but I have created a new physics on it... :)) Anyway it have NO any conection to the Lorentz's transformation. Well, it's not a point, the point is thanks you for your time, this forum is indeed good in terms of users trying to help by topic at least!
 
  • #65
My last formal education was in the early 1970's, but I always kept current and could consider my speculations valid. So I thought.
I joined Physics Forums with a very important view and got swatted immediately.
A bit upset, I decided to take it, study up a bit, the devastate the narrow minded.

It turned out I could not afford to return to school full time for the years it would take to actually replace my aged and misguided past with the reality of what has been learned since.
Human nature has me holding on to my speculations, but, like Einstein in his later years, I have to just plain ignore many newer and proven observations. So be it.

I empathize with frostysh and am curious if the last of his formal education was anywhere near the same time period as mine.
 

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