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Old July 8th 13, 09:52 AM posted to sci.astro
Pentcho Valev
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When the observer starts moving towards (away from) the light source, antirelativists see the frequency and the speed of the light waves relative to the observer change while the wavelength remains unchanged. In contrast, relativists see the frequency and the wavelength change while the speed of the light waves relative to the observer remains unchanged, Divine Einstein, yes we all believe in relativity, relativity, relativity:

Introductory Astronomy: Doppler Effect Basics

Dr Ricardo Eusebi: "f'=f(1+v/c). Light frequency is relative to the observer. The velocity is not though. The velocity is the same in all the reference frames."

"The observer moves closer to the source. The wave received has a shorter wavelength (higher frequency) than that emitted by the source. The observer moves away from the source. The wave received has a longer wavelength (lower frequency) than that emitted by the source."

Mad antirelativists or mad relativists?

Pentcho Valev
Old July 8th 13, 12:29 PM posted to sci.astro
Pentcho Valev
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Posts: 7,521

The special relativity tenet that the moving observer meets more wavecrests per unit time than the stationary observer but the speed of the wavecrests relative to both observers is the same (Divine Einstein, yes we all believe in relativity, relativity, relativity) is so absurd that, except for the silliest Einsteinians, no one believes in it. This is not a serious problem in Divine Albert's world - teachers only have to be careful not to draw students' attention to the absurdity. Yet some teachers are careless and suggest that the speed of light (relative to the observer) does vary with the speed of the observer. Students do not know that this is fatal for special relativity but even if they did, they would not react. In Divine Albert's world both teachers and students simply couldn't care less about whether or not science is true:

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."

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. (...) 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: (...) 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."

"vO is the velocity of an observer moving towards the source. This velocity is independent of the motion of the source. Hence, the velocity of waves relative to the observer is c + vO. (...) The motion of an observer does not alter the wavelength. The increase in frequency is a result of the observer encountering more wavelengths in a given time."

University of Texas: "Thus, the moving observer sees a wave possessing the same wavelength (...) but a different frequency (...) to that seen by the stationary observer. This phenomenon is known as the Doppler effect."

"La variation de la fréquence observée lorsqu'il y a mouvement relatif entre la source et l'observateur est appelée effet Doppler. (...) 6. Source immobile - Observateur en mouvement: La distance entre les crêtes, la longueur d'onde lambda ne change pas. Mais la vitesse des crêtes par rapport à l'observateur change !"

"L'effet Doppler est le décalage de fréquence d'une onde acoustique ou électromagnétique entre la mesure à l'émission et la mesure à la réception lorsque la distance entre l'émetteur et le récepteur varie au cours du temps. (...) Pour comprendre ce phénomène, il s'agit de penser à une onde à une fréquence donnée qui est émise vers un observateur en mouvement, ou vis-versa. LA LONGUEUR D'ONDE DU SIGNAL EST CONSTANTE mais si l'observateur se rapproche de la source, il se déplace vers les fronts d'ondes successifs et perçoit donc plus d'ondes par seconde que s'il était resté stationnaire, donc une augmentation de la fréquence.. De la même manière, s'il s'éloigne de la source, les fronts d'onde l'atteindront avec un retard qui dépend de sa vitesse d'éloignement, donc une diminution de la fréquence. Dans le cas sonore, cela se traduit par un son plus aigu lors d'un rapprochement de la source et un son plus grave en s'éloignant de celle-ci. Dans le domaine de la lumière visible, on parle de décalage vers le bleu pour un rapprochement et vers le rouge dans le cas d'éloignement en se référant au spectre lumineux. La même chose s'applique à toutes les gammes d'ondes électromagnétiques dont les ondes utilisées par les radars."

Fang-Yuh Lo, Department of Physics, National Taiwan Normal University: "Observer moves toward source: frequency becomes higher. Observer moves away from source: frequency becomes lower. How much higher (lower)? Wavelength does not change. Change in velocity: Vnew=Vwave±Vobs."

"Doppler effect (...) Let u be speed of source or observer (...) Doppler Shift: Moving Observer. Shift in frequency only, wavelength does not change. Speed observed = v+u (...) Observed frequency shift f'=f(1±u/v)"

"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)."

"Consider the case where the observer moves toward the source. In this case, the observer is rushing head-long into the wavefronts, so that we expect v'v. In fact, the wave speed is simply increased by the observer speed, as we can see by jumping into the observer's frame of reference. Thus, v'=v+v_o=v(1+v_o/v). Finally, the frequency must increase by exactly the same factor as the wave speed increased, in order to ensure that L'=L - v'/f'=v/f. Putting everything together, we thus have: OBSERVER MOVING TOWARD SOURCE: L'=L; f'=f(1+v_o/v); v'=v+v_o."

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."

Pentcho Valev
Old July 9th 13, 06:49 AM posted to sci.astro
Pentcho Valev
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Posts: 7,521

Destruction of students' rationality in Divine Albert's world: The following video teaches that, when the observer starts moving towards the light source, "wavelengths are going to condense and so the frequency is going to be higher". Yet a transient note informs the student that "the wavelengths themselves do not actually condense, they just appear to condense to the observer":

Doppler effect for electromagnetic waves

Needless to say, wavelengths' strange behavior - they do not condense but appear to condense so that the observer could measure the same speed of the waves, Divine Einstein, yes we all believe in relativity, relativity, relativity - occurs only in Divine Albert's world. In a world different from Divine Albert's world the wavelength would be independent of the motion of the observer and the frequency shift in light waves, just like the frequency shift in sound waves, would be caused by a shift in the speed of the waves as measured by the observer:

"Sound waves have speed c, and f and L are related by c=Lf. For an observer moving relative to medium with speed u, apparent propagation speed c' will be different: c'=c±u. Wavelength cannot change - it's a constant length in the medium, and same length in moving coordinate system (motion does not change lengths). Observed frequency has to change, to match apparent speed and fixed wavelength: f'=c'/L."

See more he

Shift in Frequency Implies Shift in Speed of Light

Pentcho Valev

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