Discussion:
Richard Feynman Lying About Gravitational Time Dilation
(trop ancien pour répondre)
Pentcho Valev
2017-09-03 08:19:51 UTC
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Richard Feynman: "Suppose we put a clock at the "head" of the rocket ship - that is, at the front end - and we put another identical clock at the "tail," as in fig. 42-16. Let's call the two clocks A and B. If we compare these two clocks when the ship is accelerating, the clock at the head seems to run fast relative to the one at the tail. To see that, imagine that the front clock emits a flash of light each second, and that you are sitting at the tail comparing the arrival of the light flashes with the ticks of clock B. [...] You can see, then, that if the two flashes were emitted from clock A one second apart, they would arrive at clock B with a separation somewhat less than one second... [...] But now let's think of the rocket ship at rest in the earth's gravity. The same thing happens." http://www.feynmanlectures.caltech.edu/II_42.html

Feynman's argument amounts to

Since the frequency of arrival at clock B is higher, there is gravitational time dilation.

which is a lie. Actually there is no gravitational time dilation - the higher frequency is due to the increased speed of light. In a gravitational field light falls with the same acceleration as ordinary falling bodies - on the Earth, the acceleration of falling photons is g. This is an obvious consequence of the equivalence principle and many Einsteinians teach it, not knowing that in this case "g" is fatal for Einstein's relativity:

"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." http://sethi.lamar.edu/bahrim-cristian/Courses/PHYS4480/4480-PROBLEMS/optics-gravit-lens_PPT.pdf

This variation of the speed of light in a gravitational field (predicted by Newton's emission theory) has been confirmed experimentally:

University of Illinois at Urbana-Champaign: "Consider a falling object. ITS SPEED 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. Consider a light beam that is travelling away from a gravitational field. Its frequency should shift to lower values. This is known as the gravitational red shift of light." https://courses.physics.illinois.edu/phys419/sp2011/lectures/Lecture13/L13r.html

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 inertial mass) suffices. [...] The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..." http://www.einstein-online.info/spotlights/redshift_white_dwarfs

Pound, Rebka and Snider knew that their experiments had confirmed the variation of the speed of light predicted by Newton's emission theory of light, not the gravitational time dilation predicted by Einstein's relativity:

R. V. Pound and G. A. Rebka, Jr, APPARENT WEIGHT OF PHOTONS http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.4.337

R. V. Pound and J. L. Snider, Effect of Gravity on Gamma Radiation: "It is not our purpose here to enter into the many-sided discussion of the relationship between the effect under study and general relativity or energy conservation. It is to be noted that no strictly relativistic concepts are involved and the description of the effect as an "apparent weight" of photons is suggestive. The velocity difference predicted is identical to that which a material object would acquire in free fall for a time equal to the time of flight." http://virgo.lal.in2p3.fr/NPAC/relativite_fichiers/pound.pdf

Pentcho Valev
l***@wanadoo.fr
2017-09-03 12:13:21 UTC
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Post by Pentcho Valev
Richard Feynman: "Suppose we put a clock at the "head" of the rocket ship - that is, at the front end - and we put another identical clock at the "tail," as in fig. 42-16. Let's call the two clocks A and B. If we compare these two clocks when the ship is accelerating, the clock at the head seems to run fast relative to the one at the tail. To see that, imagine that the front clock emits a flash of light each second, and that you are sitting at the tail comparing the arrival of the light flashes with the ticks of clock B. [...] You can see, then, that if the two flashes were emitted from clock A one second apart, they would arrive at clock B with a separation somewhat less than one second... [...] But now let's think of the rocket ship at rest in the earth's gravity. The same thing happens." http://www.feynmanlectures.caltech.edu/II_42.html
Feynman's argument amounts to
Since the frequency of arrival at clock B is higher, there is gravitational time dilation.
"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." http://sethi.lamar.edu/bahrim-cristian/Courses/PHYS4480/4480-PROBLEMS/optics-gravit-lens_PPT.pdf
University of Illinois at Urbana-Champaign: "Consider a falling object. ITS SPEED 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. Consider a light beam that is travelling away from a gravitational field. Its frequency should shift to lower values. This is known as the gravitational red shift of light." https://courses.physics.illinois.edu/phys419/sp2011/lectures/Lecture13/L13r.html
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 inertial mass) suffices. [...] The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..." http://www.einstein-online.info/spotlights/redshift_white_dwarfs
R. V. Pound and G. A. Rebka, Jr, APPARENT WEIGHT OF PHOTONS http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.4.337
R. V. Pound and J. L. Snider, Effect of Gravity on Gamma Radiation: "It is not our purpose here to enter into the many-sided discussion of the relationship between the effect under study and general relativity or energy conservation. It is to be noted that no strictly relativistic concepts are involved and the description of the effect as an "apparent weight" of photons is suggestive. The velocity difference predicted is identical to that which a material object would acquire in free fall for a time equal to the time of flight." http://virgo.lal.in2p3.fr/NPAC/relativite_fichiers/pound.pdf
Pentcho Valev
meuh oui ! comme disent les vaches en regardant Nemo, premier chien de France,
se promener sur les Champs-Elisées
--
L.C.
Pentcho Valev
2017-09-04 07:44:58 UTC
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Banesh Hoffmann: "All the clocks go at the same rate" (that is, THERE IS NO GRAVITATIONAL TIME DILATION) - the gravitational redshift "arises from what befalls light signals as they traverse space and time in the presence of gravitation":

Banesh Hoffmann: "In an accelerated sky laboratory, and therefore also in the corresponding earth laboratory, the frequence of arrival of light pulses is lower than the ticking rate of the upper clocks even though all the clocks go at the same rate. [...] As a result the experimenter at the ceiling of the sky laboratory will see with his own eyes that the floor clock is going at a slower rate than the ceiling clock - even though, as I have stressed, both are going at the same rate. [...] The gravitational red shift does not arise from changes in the intrinsic rates of clocks. It arises from what befalls light signals as they traverse space and time in the presence of gravitation." http://www.amazon.com/Relativity-Its-Roots-Banesh-Hoffmann/dp/0486406768

What "befalls light signals as they traverse space and time in the presence of gravitation"? They accelerate of course, like ordinary falling bodies and particles (in the gravitational field of the Earth the acceleration of falling photons is g), as predicted by Newton's emission theory of light and in violation of Einstein's relativity:

http://sethi.lamar.edu/bahrim-cristian/Courses/PHYS4480/4480-PROBLEMS/optics-gravit-lens_PPT.pdf
"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." x

https://courses.physics.illinois.edu/phys419/sp2011/lectures/Lecture13/L13r.html
University of Illinois at Urbana-Champaign: "Consider a falling object. ITS SPEED 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. Consider a light beam that is travelling away from a gravitational field. Its frequency should shift to lower values. This is known as the gravitational red shift of light." x

http://www.einstein-online.info/spotlights/redshift_white_dwarfs
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 inertial mass) suffices. [...] The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..." x

Richard Feynman: "I want to emphasize that light comes in this form - particles. It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you probably learned something about light behaving like waves. I'm telling you the way it does behave - like particles. You might say that it's just the photomultiplier that detects light as particles, but no, every instrument that has been designed to be sensitive enough to detect weak light has always ended up discovering the same thing: light is made of particles." QED: The Strange Theory of Light and Matter p. 15 http://www.amazon.com/QED-Strange-Theory-Light-Matter/dp/0691024170

Pentcho Valev

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