Pentcho Valev
2015-08-08 08:51:54 UTC
http://strangebeautiful.com/lmu/readings/einstein-rel-prob.pdf
Albert Einstein: "It is easy to specify wherein lies the apparent contradiction between Maxwell-Lorentz electrodynamics and the relativity principle. Suppose that the equations of that theory hold relative to the coordinate system K. This means that every light ray propagates in vacuo with a definite velocity c, with respect to K, which is independent of direction and of the state of motion of the light source; this proposition will be called the "principle of the constancy of the speed of light" in the following. Now if one such light ray were to be observed by an observer moving relative to K, then the propagation speed of this light ray, as estimated from the standpoint of this observer, in general seems to be different than c. For example, if the light ray propagates in the direction of the positive x-axis of K with speed c, and our observer moves in the same direction with the temporally constant speed v, then one would believe that one can immediately conclude that the light ray's propagation speed must be c-v according to the moving observer. Relative to the observer, that is, relative to a coordinate system K' moving with the same velocity, the principle of the constancy of the speed of light does not appear to hold. Hence, here is an apparent contradiction with the principle of relativity.
However, an exact analysis of the physical content of our spatial and temporal determinations leads to the well-known result that the implied contradiction is only apparent, since it depends on both of the following arbitrary assumptions:
1. The assertion that whether two events occurring in different places occur simultaneously has content independently of the choice of a reference system.
2. The spatial distance between the places in which two simultaneous events occur is independent of the choice of a reference system.
Given that the Maxwell-Lorentz theory as well as the relativity principle are empirically supported to such a large degree, one must therefore decide to drop both the aforementioned arbitrary assumptions, the apparent evidence for which rests solely on the facts that light gives us information about distant events apparently instantaneously, and that the objects we deal with in daily life have velocities that are small compared to the velocity of light c.
By abandoning these arbitrary assumptions, one achieves compatibility between the principle of the constancy of the speed of light, which results from Maxwell-Lorentz electrodynamics, and the relativity principle."
______________________________________
[end of quotation]
The "principle of the constancy of the speed of light" (the speed of light is independent of the state of motion of the light source) and the principle of relativity were incompatible indeed, so Einstein should have declared the former false (the relativity principle cannot be doubted). Yet in the above text he defends the false constant-speed-of-light principle by idiotically asserting that it is a tenet of a previous theory which is "empirically supported to such a large degree".
In fact, basically, the "principle of the constancy of the speed of light" was a tenet of the discredited ether theory:
http://books.google.com/books?id=JokgnS1JtmMC
"Relativity and Its Roots" by Banesh Hoffmann, p.92: "There are various remarks to be made about this second principle. For instance, if it is so obvious, how could it turn out to be part of a revolution - especially when the first principle is also a natural one? Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether. If it was so obvious, though, why did he need to state it as a principle? Because, having taken from the idea of light waves in the ether the one aspect that he needed, he declared early in his paper, to quote his own words, that "the introduction of a 'luminiferous ether' will prove to be superfluous."
Needless to say, the false "principle of the constancy of the speed of light" could not have any experimental support:
http://www.amazon.com/Introduction-Special-Relativity-James-Smith/dp/048668895X
Introduction to Special Relativity, James H. Smith, p. 42: "We must emphasize that at the time Einstein proposed it [his second postulate], there was no direct experimental evidence whatever for the speed of light being independent of the speed of its source. He postulated it out of logical necessity."
Pentcho Valev
Albert Einstein: "It is easy to specify wherein lies the apparent contradiction between Maxwell-Lorentz electrodynamics and the relativity principle. Suppose that the equations of that theory hold relative to the coordinate system K. This means that every light ray propagates in vacuo with a definite velocity c, with respect to K, which is independent of direction and of the state of motion of the light source; this proposition will be called the "principle of the constancy of the speed of light" in the following. Now if one such light ray were to be observed by an observer moving relative to K, then the propagation speed of this light ray, as estimated from the standpoint of this observer, in general seems to be different than c. For example, if the light ray propagates in the direction of the positive x-axis of K with speed c, and our observer moves in the same direction with the temporally constant speed v, then one would believe that one can immediately conclude that the light ray's propagation speed must be c-v according to the moving observer. Relative to the observer, that is, relative to a coordinate system K' moving with the same velocity, the principle of the constancy of the speed of light does not appear to hold. Hence, here is an apparent contradiction with the principle of relativity.
However, an exact analysis of the physical content of our spatial and temporal determinations leads to the well-known result that the implied contradiction is only apparent, since it depends on both of the following arbitrary assumptions:
1. The assertion that whether two events occurring in different places occur simultaneously has content independently of the choice of a reference system.
2. The spatial distance between the places in which two simultaneous events occur is independent of the choice of a reference system.
Given that the Maxwell-Lorentz theory as well as the relativity principle are empirically supported to such a large degree, one must therefore decide to drop both the aforementioned arbitrary assumptions, the apparent evidence for which rests solely on the facts that light gives us information about distant events apparently instantaneously, and that the objects we deal with in daily life have velocities that are small compared to the velocity of light c.
By abandoning these arbitrary assumptions, one achieves compatibility between the principle of the constancy of the speed of light, which results from Maxwell-Lorentz electrodynamics, and the relativity principle."
______________________________________
[end of quotation]
The "principle of the constancy of the speed of light" (the speed of light is independent of the state of motion of the light source) and the principle of relativity were incompatible indeed, so Einstein should have declared the former false (the relativity principle cannot be doubted). Yet in the above text he defends the false constant-speed-of-light principle by idiotically asserting that it is a tenet of a previous theory which is "empirically supported to such a large degree".
In fact, basically, the "principle of the constancy of the speed of light" was a tenet of the discredited ether theory:
http://books.google.com/books?id=JokgnS1JtmMC
"Relativity and Its Roots" by Banesh Hoffmann, p.92: "There are various remarks to be made about this second principle. For instance, if it is so obvious, how could it turn out to be part of a revolution - especially when the first principle is also a natural one? Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether. If it was so obvious, though, why did he need to state it as a principle? Because, having taken from the idea of light waves in the ether the one aspect that he needed, he declared early in his paper, to quote his own words, that "the introduction of a 'luminiferous ether' will prove to be superfluous."
Needless to say, the false "principle of the constancy of the speed of light" could not have any experimental support:
http://www.amazon.com/Introduction-Special-Relativity-James-Smith/dp/048668895X
Introduction to Special Relativity, James H. Smith, p. 42: "We must emphasize that at the time Einstein proposed it [his second postulate], there was no direct experimental evidence whatever for the speed of light being independent of the speed of its source. He postulated it out of logical necessity."
Pentcho Valev