# Speed of Light in Gravity : Newton? Einstein?

#### Pentcho Valev

As light falls in a gravitational field, what happens to its speed?

The Newtonian prediction is straightforward (it is so obviously true that even Einsteinians teach it explicitly):

James Hartle, Gravity: An Introduction to Einstein's General Relativity, p. 113: "If we accept the equivalence principle, we must also accept that light falls in a gravitational field with the same acceleration as material bodies." https://www.amazon.com/Gravity-Introduction-Einsteins-General-Relativity/dp/0805386629

Paul A. Tipler, Ralph A. Llewellyn, Modern Physics: "To see why a deflection of light would be expected, consider Figure 2-17, which shows a beam of light entering an accelerating compartment. Successive positions of the compartment are shown at equal time intervals. Because the compartment is accelerating, the distance it moves in each time interval increases with time. The path of the beam of light, as observed from inside the compartment, is therefore a parabola. But according to the equivalence principle, there is no way to distinguish between an accelerating compartment and one with uniform velocity in a uniform gravitational field. We conclude, therefore, that A BEAM OF LIGHT WILL ACCELERATE IN A GRAVITATIONAL FIELD AS DO OBJECTS WITH REST MASS. For example, near the surface of Earth light will fall with acceleration 9.8 m/s^2." http://web.pdx.edu/~pmoeck/books/Tipler_Llewellyn.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." https://courses.physics.illinois.edu/phys419/sp2011/lectures/Lecture13/L13r.html

The Einsteinian prediction? As light falls in a gravitational field, what happens to its speed, according to general relativity? Normally, scientists couldn't care less (post-truth science), but if someone does care and starts searching the Internet, he/she will find...no answer. There are no authoritative sources discussing the issue. A few apparently marginal sources suggest that, according to general relativity, the speed of falling light, unlike the speed of ordinary falling objects, DECREASES. The language in these marginal sources is confusing and contradictory, so citing them is useless, if not counterproductive.

Einstein himself has repeated countless times that the speed of light varies in a gravitational field, but never explained how it varies. Something is rotten in the state of Denmark, isn't it?

#### Debed

As light falls in a gravitational field, what happens to its speed?

The Newtonian prediction is straightforward (it is so obviously true that even Einsteinians teach it explicitly):

James Hartle, Gravity: An Introduction to Einstein's General Relativity, p. 113: "If we accept the equivalence principle, we must also accept that light falls in a gravitational field with the same acceleration as material bodies." https://www.amazon.com/Gravity-Introduction-Einsteins-General-Relativity/dp/0805386629

Paul A. Tipler, Ralph A. Llewellyn, Modern Physics: "To see why a deflection of light would be expected, consider Figure 2-17, which shows a beam of light entering an accelerating compartment. Successive positions of the compartment are shown at equal time intervals. Because the compartment is accelerating, the distance it moves in each time interval increases with time. The path of the beam of light, as observed from inside the compartment, is therefore a parabola. But according to the equivalence principle, there is no way to distinguish between an accelerating compartment and one with uniform velocity in a uniform gravitational field. We conclude, therefore, that A BEAM OF LIGHT WILL ACCELERATE IN A GRAVITATIONAL FIELD AS DO OBJECTS WITH REST MASS. For example, near the surface of Earth light will fall with acceleration 9.8 m/s^2." http://web.pdx.edu/~pmoeck/books/Tipler_Llewellyn.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." https://courses.physics.illinois.edu/phys419/sp2011/lectures/Lecture13/L13r.html

The Einsteinian prediction? As light falls in a gravitational field, what happens to its speed, according to general relativity? Normally, scientists couldn't care less (post-truth science), but if someone does care and starts searching the Internet, he/she will find...no answer. There are no authoritative sources discussing the issue. A few apparently marginal sources suggest that, according to general relativity, the speed of falling light, unlike the speed of ordinary falling objects, DECREASES. The language in these marginal sources is confusing and contradictory, so citing them is useless, if not counterproductive.

Einstein himself has repeated countless times that the speed of light varies in a gravitational field, but never explained how it varies. Something is rotten in the state of Denmark, isn't it?

So a light curving a blackhole would go faster than the speed of light in other words.
Same way as we slingshot satellites around planets to speed them up (and to slow them down, but let us focus on the speeding up part for now).
And yet, we have not detected a single beam of light, breaking the speed barrier, when we have pointed our tools in the direction of blackholes.

#### Pentcho Valev

Albert Einstein: "The gravitational force bends the light ray as if light were a catapulted heavy body. This consequence is of great significance in a twofold way. First... [...] Second, this consequence shows that the law of the constancy of the speed of light no longer holds, according to the general theory of relativity, in spaces that have gravitational fields. As a simple geometric consideration shows, the curvature of light rays occurs only in spaces where the speed of light is spatially variable." https://einsteinpapers.press.princeton.edu/vol7-trans/155

So, according to Einstein, bending of light shows that the speed of light varies in a gravitational field. But what precisely does bending show? As light falls towards the source of gravity, its speed increases or decreases? Neither Einstein nor any high priest in the Einstein Cult would answer this question.

Yet the question has an obvious answer, so obvious that ordinary Einsteinians often leave Einstein's schizophrenic world for a while and tell the truth. Bending shows that the speed of falling light INCREASES as per Newton:

"To see WHY A DEFLECTION OF LIGHT WOULD BE EXPECTED, consider Figure 2-17, which shows a beam of light entering an accelerating compartment. Successive positions of the compartment are shown at equal time intervals. Because the compartment is accelerating, the distance it moves in each time interval increases with time. The path of the beam of light, as observed from inside the compartment, is therefore a parabola. But according to the equivalence principle, there is no way to distinguish between an accelerating compartment and one with uniform velocity in a uniform gravitational field. We conclude, therefore, that A BEAM OF LIGHT WILL ACCELERATE IN A GRAVITATIONAL FIELD AS DO OBJECTS WITH REST MASS. For example, near the surface of Earth light will fall with acceleration 9.8 m/s^2." http://web.pdx.edu/~pmoeck/books/Tipler_Llewellyn.pdf

Why are high priests in the Einstein Cult adamantly silent in this particular case? Because Einstein's general relativity predicts that the speed of falling light DECREASES, and this is so preposterous that the hypnotised scientific community may suddenly wake up and then...lasciatemi morire:

#### Debed

Albert Einstein: "The gravitational force bends the light ray as if light were a catapulted heavy body. This consequence is of great significance in a twofold way. First... [...] Second, this consequence shows that the law of the constancy of the speed of light no longer holds, according to the general theory of relativity, in spaces that have gravitational fields. As a simple geometric consideration shows, the curvature of light rays occurs only in spaces where the speed of light is spatially variable." https://einsteinpapers.press.princeton.edu/vol7-trans/155

So, according to Einstein, bending of light shows that the speed of light varies in a gravitational field. But what precisely does bending show? As light falls towards the source of gravity, its speed increases or decreases? Neither Einstein nor any high priest in the Einstein Cult would answer this question.

Yet the question has an obvious answer, so obvious that ordinary Einsteinians often leave Einstein's schizophrenic world for a while and tell the truth. Bending shows that the speed of falling light INCREASES as per Newton:

"To see WHY A DEFLECTION OF LIGHT WOULD BE EXPECTED, consider Figure 2-17, which shows a beam of light entering an accelerating compartment. Successive positions of the compartment are shown at equal time intervals. Because the compartment is accelerating, the distance it moves in each time interval increases with time. The path of the beam of light, as observed from inside the compartment, is therefore a parabola. But according to the equivalence principle, there is no way to distinguish between an accelerating compartment and one with uniform velocity in a uniform gravitational field. We conclude, therefore, that A BEAM OF LIGHT WILL ACCELERATE IN A GRAVITATIONAL FIELD AS DO OBJECTS WITH REST MASS. For example, near the surface of Earth light will fall with acceleration 9.8 m/s^2." http://web.pdx.edu/~pmoeck/books/Tipler_Llewellyn.pdf

Why are high priests in the Einstein Cult adamantly silent in this particular case? Because Einstein's general relativity predicts that the speed of falling light DECREASES, and this is so preposterous that the hypnotised scientific community may suddenly wake up and then...lasciatemi morire:

Do you missunderstand things on purpose?
Gravitation does not bend the light.
Mass warps the fabric of space around it.

imagine a trampoline, in vacuum, and you roll a tennisball across it. All fine and dandy, right. The tennis ball goes straight forward.
Now you place a bowlingball in the middle of the trampoline and you roll a tennisball. The tennisball now follows the dip made by the bowlingball before reaching the other end.
the tennis ball was not affected by the gravity of the bowling ball, it merely followed the dip made by the bowlingball.

That is why we can use other galaxies and such as a magnifier and see what is beyond the galaxy

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