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OBSERVER-DEPENDENT SPEED OF LIGHT



 
 
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  #1  
Old September 12th 12, 08:26 PM posted to sci.astro
Pentcho Valev
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Default OBSERVER-DEPENDENT SPEED OF LIGHT

The speed of light (relative to the observer) varies with the speed of the observer. This is an antirelativistic statement which, somewhat paradoxically, is commonplace in the scientific literature. Scientists often forget to worship special relativity and produce texts like this one:

http://physics.bu.edu/~redner/211-sp...9_doppler.html
Professor Sidney Redner: "The Doppler effect is the shift in frequency of a wave that occurs when the wave source, or the detector of the wave, is moving. Applications of the Doppler effect range from medical tests using ultrasound to radar detectors and astronomy (with electromagnetic waves). (...) We will focus on sound waves in describing the Doppler effect, but it works for other waves too. (...) Let's say you, the observer, now move toward the source with velocity vO. You encounter more waves per unit time than you did before. Relative to you, the waves travel at a higher speed: v'=v+vO.. The frequency of the waves you detect is higher, and is given by: f'=v'/(lambda)=(v+vO)/(lambda)."

See more he

http://fqxi.org/community/forum/topic/1398
Shift in Frequency Implies Shift in Speed of Light

Pentcho Valev

  #2  
Old September 22nd 12, 06:13 AM posted to sci.astro
Pentcho Valev
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Default OBSERVER-DEPENDENT SPEED OF LIGHT

http://www.hep.man.ac.uk/u/roger/PHY.../lecture18.pdf
Roger Barlow, Professor of Particle Physics: "The Doppler effect - changes in frequencies when sources or observers are in motion - is familiar to anyone who has stood at the roadside and watched (and listened) to the cars go by. It applies to all types of wave, not just sound. (...) Moving Observer.. Now suppose the source is fixed but the observer is moving towards the source, with speed v. In time t, ct/(lambda) waves pass a fixed point. A moving point adds another vt/(lambda). So f'=(c+v)/(lambda)."

"In time t, ct/(lambda) waves pass a fixed point." That is, the speed of the waves relative to the fixed observer is c.

"A moving point adds another vt/(lambda)." That is, the speed of the waves relative to the moving observer becomes c'=c+v. The new frequency, f'=c'/(lambda)=(c+v)/(lambda), is consistent with c'=c+v.

Pentcho Valev
  #3  
Old September 22nd 12, 05:01 PM posted to sci.astro
Pentcho Valev
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Default OBSERVER-DEPENDENT SPEED OF LIGHT

http://www.cmmp.ucl.ac.uk/~ahh/teach...24n/lect19.pdf
Tony Harker, University College London: "The Doppler Effect: Moving sources and receivers. The phenomena which occur when a source of sound is in motion are well known. The example which is usually cited is the change in pitch of the engine of a moving vehicle as it approaches. In our treatment we shall not specify the type of wave motion involved, and our results will be applicable to sound or to light. (...) Now suppose that the observer is moving with a velocity Vo away from the source. (...) If the observer moves with a speed Vo away from the source (...), then in a time t the number of waves which reach the observer are those in a distance (c-Vo)t, so the number of waves observed is (c-Vo)t/lambda, giving an observed frequency f'=f(1-Vo/c) when the observer is moving away from the source at a speed Vo."

If "in a time t the number of waves which reach the observer are those in a distance (c-Vo)t", then the speed of the light waves relative to the observer is c'=c-Vo.

Pentcho Valev
  #4  
Old September 22nd 12, 09:20 PM posted to sci.astro
Brad Guth[_3_]
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Default OBSERVER-DEPENDENT SPEED OF LIGHT

On Sep 12, 12:26*pm, Pentcho Valev wrote:
The speed of light (relative to the observer) varies with the speed of the observer. This is an antirelativistic statement which, somewhat paradoxically, is commonplace in the scientific literature. Scientists often forget to worship special relativity and produce texts like this one:

http://physics.bu.edu/~redner/211-sp...9_doppler.html
Professor Sidney Redner: "The Doppler effect is the shift in frequency of a wave that occurs when the wave source, or the detector of the wave, is moving. Applications of the Doppler effect range from medical tests using ultrasound to radar detectors and astronomy (with electromagnetic waves). (....) We will focus on sound waves in describing the Doppler effect, but it works for other waves too. (...) Let's say you, the observer, now move toward the source with velocity vO. You encounter more waves per unit time than you did before. Relative to you, the waves travel at a higher speed: v'=v+vO. The frequency of the waves you detect is higher, and is given by: f'=v'/(lambda)=(v+vO)/(lambda)."

See more he

http://fqxi.org/community/forum/topic/1398
Shift in Frequency Implies Shift in Speed of Light

Pentcho Valev


Yes, detecting more waves by heading yourself towards the source of
them waves is going to cause the detection of such extra waves as
represented by a higher frequency. If you could travel fast enough
directly away from the wave source, absolutely nothing could be
detected regardless of the original wave frequency.

Aether as the grand all-inclusive medium of space is kinda funny that
way.

However, it seems an established beam of quantum entanglement photons
are proven as capable of acting as fast or just as instantaneous as
gravity.
..
http://groups.google.com/groups/search
http://translate.google.com/#
Brad Guth,Brad_Guth,Brad.Guth,BradGuth,BG,Guth Usenet/”Guth Venus”
  #5  
Old September 23rd 12, 06:34 AM posted to sci.astro
Pentcho Valev
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Posts: 8,078
Default OBSERVER-DEPENDENT SPEED OF LIGHT

http://ef.engr.utk.edu/ef152-2008-08...52-lec-4-2.pdf
"If an observer moves towards a stationary source with speed Vr, the observer sees the wave crests with a speed:

V' = V + Vr

Wavelength remains the same, so the modified frequency is:

f' = V'/(lambda) = (V + Vr)/(lambda) = fo(1 + Vr/V)"

Pentcho Valev
  #6  
Old September 24th 12, 01:14 PM posted to sci.astro
Pentcho Valev
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Posts: 8,078
Default OBSERVER-DEPENDENT SPEED OF LIGHT

http://www.einstein-online.info/spotlights/doppler
Albert Einstein Institute: "The frequency of a wave-like signal - such as sound or light - depends on the movement of the sender and of the receiver. This is known as the Doppler effect. (...) Here is an animation of the receiver moving towards the source: (...) 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."

That is, the motion of the observer cannot change the wavelength ("the distances between subsequent pulses are not affected") and accordingly the speed of light as measured by the receiver is (4/3)c.

Pentcho Valev
  #7  
Old October 16th 12, 04:30 AM
Tinech Tinech is offline
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Quote:
Originally Posted by Pentcho Valev View Post
http://www.hep.man.ac.uk/u/roger/PHY.../lecture18.pdf front page
Roger Barlow, Professor of Particle Physics: "The Doppler effect - changes in frequencies when sources or observers are in motion - is familiar to anyone who has stood at the roadside and watched (and listened) to the cars go by. It applies to all types of wave, not just sound. (...) Moving Observer.. Now suppose the source is fixed but the observer is moving towards the source, with speed v. In time t, ct/(lambda) waves pass a fixed point. A moving point adds another vt/(lambda). So f'=(c+v)/(lambda)."

"In time t, ct/(lambda) waves pass a fixed point." That is, the speed of the waves relative to the fixed observer is c.

"A moving point adds another vt/(lambda)." That is, the speed of the waves relative to the moving observer becomes c'=c+v. The new frequency, f'=c'/(lambda)=(c+v)/(lambda), is consistent with c'=c+v.

Pentcho Valev

I have read this physics concept in 11 standard. So thanks for reminding it again.

Last edited by Tinech : October 16th 12 at 07:23 AM.
 




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