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Obviously Variable (Newtonian) Speed of Light in Doppler



 
 
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  #1  
Old October 25th 20, 11:07 PM posted to sci.astro
Pentcho Valev
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Default Obviously Variable (Newtonian) Speed of Light in Doppler

Doppler effect in light (moving observer):

https://www.youtube.com/watch?v=bg7O4rtlwEE

The speed of the light pulses as measured by the stationary observer is

c = df

where d is the distance between the pulses and f is the frequency measured by the stationary observer. The speed of the pulses as measured by the moving observer is

c'= df' c

where f' f is the frequency measured by the moving observer.

See more he https://twitter.com/pentcho_valev

Pentcho Valev
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  #2  
Old October 26th 20, 10:03 AM posted to sci.astro
Anders Eklöf
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Default Obviously Variable (Newtonian) Speed of Light in Doppler

Pentcho Valev wrote:

Doppler effect in light (moving observer):

https://www.youtube.com/watch?v=bg7O4rtlwEE

The speed of the light pulses as measured by the stationary observer is

c = df

where d is the distance between the pulses and f is the frequency measured

by the stationary observer. The speed of the pulses as measured by the
moving observer is

c'= df' c

where f' f is the frequency measured by the moving observer.

See more he https://twitter.com/pentcho_valev

Pentcho Valev


The correct word is of course apparently, not obviously.

Since your "explanations" systematically ignore the effects of time
dilation and length contraction they have no relevance to relativity.
These effects in special relativity explain the Doppler effect for light
just fine.

Newton knew nothing about relativity, so in a Newtioan system the speed
of light *appears* to be variable.

I guess it's a moot point trying to explain this to you...

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  #3  
Old October 26th 20, 02:20 PM posted to sci.astro
Pentcho Valev
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Posts: 7,968
Default Obviously Variable (Newtonian) Speed of Light in Doppler

Doppler effect - when an observer moves toward a stationary source https://www.youtube.com/watch?v=bg7O4rtlwEE

"Now let's see what this does to the frequency of the light. We know that even without special relativity, observers moving at different velocities measure different frequencies. (This is the reason the pitch of an ambulance changes as it passes you it doesn't change if you're on the ambulance). This is called the Doppler shift, and for small relative velocity v it is easy to show that the frequency shifts from f to f(1+v/c)... There are relativistic corrections, but these are negligible here." http://galileo.phys.virginia.edu/~pf7a/modd35.pdf

The frequency shifts from f to f' = f(1+v/c) = (c+v)/d, where d is the distance between the pulses and f is the frequency measured by the stationary observer. Accordingly, the speed of the pulses as measured by the moving observer is

c'= df' = c + v

in violation of Einstein's relativity.

The conclusion remains essentially the same even if the relative velocity v is great and the relativistic corrections are not negligible.

Pentcho Valev
  #4  
Old October 26th 20, 02:52 PM posted to sci.astro
Pentcho Valev
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Posts: 7,968
Default Obviously Variable (Newtonian) Speed of Light in Doppler

Albert Einstein Institute: "In the above paragraphs, we have only considered moving sources. In fact, a closer look at cases where it is the receiver that is in motion will show that this kind of motion leads to a very similar kind of Doppler effect. Here is an animation of the receiver moving towards the source:

https://www.einstein-online.info/wp-...ein-Online.gif

By observing the two indicator lights, you can see for yourself that, once more, there is a blue-shift - the pulse frequency measured at the receiver is somewhat higher than the frequency with which the pulses are sent out. This time, the distances between subsequent pulses are not affected, but still there is a frequency shift: As the receiver moves towards each pulse, the time until pulse and receiver meet up is shortened. In this particular animation, which has the receiver moving towards the source at one third the speed of the pulses themselves, four pulses are received in the time it takes the source to emit three pulses." http://www.einstein-online.info/spotlights/doppler.html

The speed of the light pulses as measured by the source is c = 3d/t, where d is the distance between the pulses and t is "the time it takes the source to emit three pulses".

The speed of the pulses as measured by the moving receiver is c' = 4d/t c, in violation of Einstein's relativity.

More he https://twitter.com/pentcho_valev

Pentcho Valev
  #5  
Old October 26th 20, 09:55 PM posted to sci.astro
Anders Eklöf
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Default Obviously Variable (Newtonian) Speed of Light in Doppler

Pentcho Valev wrote:

Doppler effect - when an observer moves toward a stationary source
https://www.youtube.com/watch?v=bg7O4rtlwEE


I'm well aware of what Doppler effect is.

"Now let's see what this does to the frequency of the light. We know that
even without special relativity, observers moving at different velocities
measure different frequencies. (This is the reason the pitch of an
ambulance changes as it passes you it doesn't change if you're on the
ambulance). This is called the Doppler shift, and for small relative
velocity v it is easy to show that the frequency shifts from f to
f(1+v/c)... There are relativistic corrections, but these are negligible
here." http://galileo.phys.virginia.edu/~pf7a/modd35.pdf

The frequency shifts from f to f' = f(1+v/c) = (c+v)/d, where d is the
distance between the pulses and f is the frequency measured by the
stationary observer. Accordingly, the speed of the pulses as measured by
the moving observer is

c'= df' = c + v


Negligible is NOT the same as non-existent. At low speeds,
c'= df' = c + v is an acceptable approximation. Not at 0.2 c.

in violation of Einstein's relativity.


Which, as I pointed out, you ignore accounting for relativity.
Enter time dilation and Lorentz contraction and c can be constant.

The conclusion remains essentially the same even if the relative velocity
v is great and the relativistic corrections are not negligible.


Your calculations are purely Newtionian and thus irrelevant at
relativistic speeds since you don't do the relativistic corrections.
But you don't acknowledge their consequenses, so why bother?


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I recommend Macs to my friends, and Windows machines
to those whom I don't mind billing by the hour
  #6  
Old October 26th 20, 11:31 PM posted to sci.astro
Pentcho Valev
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Posts: 7,968
Default Obviously Variable (Newtonian) Speed of Light in Doppler

On Monday, October 26, 2020 at 9:56:01 PM UTC+1, Anders Eklöf wrote:

At low speeds,
c'= df' = c + v is an acceptable approximation. Not at 0.2 c.


Clever relativists are not happy with this.

Pentcho Valev
 




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