gratifiant > sci.* > sci.astrophysique

Pentcho Valev (16/05/2012, 08h31)
QUESTION 1: The frequency of light (as measured by the observer) varies with the speed of the observer. Does this mean that the speed of light (as measured by the observer) also varies with the speed of the observer, in violation of Einstein's special relativity?

Clues:


"vO is the velocity of an observer moving towards the source. This velocityis 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 notalter the wavelength. The increase in frequency is a result of the observer encountering more wavelengths in a given time."


"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 !"


Carl Mungan: "Consider the case where the observer moves toward the source.In this case, the observer is rushing head-long into the wavefronts... (....) In fact, the wave speed is simply increased by the observer speed, as wecan see by jumping into the observer's frame of reference."


Roger Barlow, Professor of Particle Physics: "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)."


Tony Harker, University College London: "If the observer moves with a speedVo 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((c-Vo)/c) when the observer is moving away from the source at a speed Vo."


Albert Einstein Institute: "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 speed of light as measured bythe receiver is (4/3)c]."

QUESTION 2: The frequency of light falling in a gravitational field increases in accordance with the equation f'=f(1+gh/c^2), as predicted by Newton's emission theory of light. Does this mean that the speed of light also increases, in accordance with another prediction of the emission theory, c'=c(1+gh/c^2)?

Clues:


University of Illinois at Urbana-Champaign: "Consider a falling object. ITSSPEED INCREASES AS IT IS FALLING. Hence, if we were to associate a frequency with that object the frequency should increase accordingly as it falls to earth. Because of the equivalence between gravitational and inertial mass, WE SHOULD OBSERVE THE SAME EFFECT FOR LIGHT. So lets shine a light beam from the top of a very tall building. If we can measure the frequency shift as the light beam descends the building, we should be able to discern how gravity affects a falling light beam. This was done by Pound and Rebka in 1960. They shone a light from the top of the Jefferson tower at Harvard and measured the frequency shift. The frequency shift was tiny but in agreement with the theoretical prediction."


Albert Einstein Institute: "One of the three classical tests for general relativity is the gravitational redshift of light or other forms of electromagnetic radiation. However, in contrast to the other two tests - the gravitational deflection of light and the relativistic perihelion shift -, you do not need general relativity to derive the correct prediction for the gravitational redshift. A combination of Newtonian gravity, a particle theory of light, and the weak equivalence principle (gravitating mass equals inertialmass) suffices."


The Gravitational Red-Shift, R.F.Evans and J.Dunning-Davies, Department of Physics, University of Hull: "Attention is drawn to the fact that the well-known expression for the red-shift of spectral lines due to a gravitationalfield may be derived with no recourse to the theory of general relativity.This raises grave doubts over the inclusion of the measurement of this gravitational red-shift in the list of crucial tests of the theory of general relativity. (...) In truth, it would seem that the result for the red-shiftof spectral lines due to the action of a gravitational field has nothing specifically to do with the theory of general relativity. It is a result which draws on more modern results due to such as Planck and Poincaré, but, apart from those, is deduced from notions of Newtonian mechanics alone."


"Relativity 3 - gravity and light"


Harvey Reall, University of Cambridge: "...light falls in the gravitationalfield in exactly the same way as a massive test particle."


Dr. Cristian Bahrim: "If we accept the principle of equivalence, we must also accept that light falls in a gravitational field with the same acceleration as material bodies."


"Le principe d'équivalence, un des fondements de base de la relativité générale prédit que dans un champ gravitationnel, la lumière tombe comme tout corps matériel selon l'acceleration de la pesanteur."


Robert W. Brehme: "Light falls in a gravitational field just as do materialobjects."

Pentcho Valev
pvalev
Pentcho Valev (16/05/2012, 14h12)
CRUCIAL QUESTION 3: Both Newton's emission theory of light and Maxwell's ether theory, unlike special relativity, predict that the frequency and the speed of light, as measured by the observer, vary with the speed of the observer. On the other hand, when the observer starts moving towards the light source with speed v (c>>v), the frequency shift seems to ALWAYS obey the equation f'=f(1+v/c). Does this support Newton's emission theory of light or Maxwell's ether theory (or both)?

ANSWER: If the frequency shift ALWAYS obeys the equation f'=f(1+v/c), then only Newton's emission theory of light gets support while Maxwell's ethertheory is refuted. The latter predicts that the frequency shifts in accordance with the equation f'=f(1+v/(c±V)), where V is the speed of the ether wind along the line connecting source and observer, relative to the source.

Pentcho Valev
pvalev
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