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Essay:Rebuttal to Counterexamples to Relativity (view source)
Revision as of 19:07, June 29, 2014
, 19:07, June 29, 2014Sorry to be long-winded, but this situation does not lend itself to superficial attempts at explanation.
#::The objection has been raised that this would still be a counterexample to Relativity.
#::The objection has been raised that this would still be a counterexample to Relativity.
#:::Yes, if it were actually true that the Moon's orbit is undergoing some kind of anomalous perturbation, it would indeed be a disproof of Relativity, Newtonian mechanics, and, in fact, all of physics since Galileo.
#:::Yes, if it were actually true that the Moon's orbit is undergoing some kind of anomalous perturbation, it would indeed be a disproof of Relativity, Newtonian mechanics, and, in fact, all of physics since Galileo.
#::::Actually, the average radius of the Moon's orbit is in fact increasing. By 38mm a year. This was first predicted in the late 19th century and actually measured since at least the early 1970's and more accurately thereafter thanks to the mirrors left for that purpose by the Apollo astronauts. The reason for this is well-known and simple enough to be explained on science-oriented TV shows from time to time. To put it simply: the Moon pulls on the Earth causing the tides and slowing down its rotation slightly, lengthening it's day by 2 milliseconds every 100 years. Reciprocally, the Earth pulls on the Moon and accelerates it slightly thus increasing the height of its orbit and energy is conserved. For a more complete explanation see <ref>http://curious.astro.cornell.edu/question.php?number=124</ref>. This behavior, predicted over 100 years ago, observed and measured, is in no way "anomalous" and relativity, general, special or otherwise doesn't really concern itself with tidal mechanics so on that point at least physics, Galilean, Newtonian and Einsteinian, are quite safe for now.
#::::Actually, the average radius of the Moon's orbit is in fact increasing. By 38mm a year. This was first predicted in the late 19th century and actually measured since at least the early 1970's and more accurately thereafter thanks to the mirrors left for that purpose by the Apollo astronauts. The reason for this is well-known and simple enough to be explained on science-oriented TV shows from time to time. To put it simply: the Moon pulls on the Earth, causing the tides and slowing down its rotation slightly, lengthening it's day by 2 milliseconds every 100 years. Reciprocally, the Earth pulls on the Moon and accelerates it slightly thus increasing the height of its orbit and energy is conserved. For a more complete explanation see <ref>http://curious.astro.cornell.edu/question.php?number=124</ref>. This behavior, predicted over 100 years ago, observed and measured, is in no way "anomalous" and relativity, general, special or otherwise doesn't really concern itself with tidal mechanics so on that point at least physics, Galilean, Newtonian and Einsteinian, are quite safe for now.
#''The Pioneer anomaly.''
#''The Pioneer anomaly.''
#:The "Pioneer anomaly" is the deviation in the motion of the Pioneer 10 and Pioneer 11 spacecraft from their predicted motion, at the distance of Saturn and beyond. It should be noted that the anomaly is about 1000 times greater than the difference between the classical Newtonian prediction and the prediction of relativity, so this is not a problem with relativity ''per se''; it is more general than that.
#:The "Pioneer anomaly" is the deviation in the motion of the Pioneer 10 and Pioneer 11 spacecraft from their predicted motion, at the distance of Saturn and beyond. It should be noted that the anomaly is about 1000 times greater than the difference between the classical Newtonian prediction and the prediction of relativity, so this is not a problem with relativity ''per se''; it is more general than that.
#''Quantum entanglement near the event horizon of a black hole ....''
#''Quantum entanglement near the event horizon of a black hole ....''
#:It is well known that quantum gravity (that is, the "Theory of Everything") is an unsolved problem, and it is the subject of much discussion in the physics community. The whole topic of string theory, for example, revolves around this. Among the places where General Relativity and Quantum Mechanics collide most notoriously is within the Planck length of a black hole's event horizon. Among the issues involved is the notion of "quantum loss of information", that was the subject of a famous bet among Stephen Hawking, Kip Thorne, and John Preskill. (Hawking and Thorne lost.) Basically, physicists do not know just what happens within quantum-mechanical distances (the Planck length) of a black hole. But no one doubts the behavior of black holes at reasonable distances, or, for that matter, General Relativity at reasonable distances.
#:It is well known that quantum gravity (that is, the "Theory of Everything") is an unsolved problem, and it is the subject of much discussion in the physics community. The whole topic of string theory, for example, revolves around this. Among the places where General Relativity and Quantum Mechanics collide most notoriously is within the Planck length of a black hole's event horizon. Among the issues involved is the notion of "quantum loss of information", that was the subject of a famous bet among Stephen Hawking, Kip Thorne, and John Preskill. (Hawking and Thorne lost.) Basically, physicists do not know just what happens within quantum-mechanical distances (the Planck length) of a black hole. But no one doubts the behavior of black holes at reasonable distances, or, for that matter, General Relativity at reasonable distances.
#''The speed of light in a vacuum is slower than expected''
#:
#:It is unfortunate that, whenever a sensational-headline-hungry writer writes anything relating to the propagation of light, they are tempted to scream something along the lines of "Einstein proved wrong." Such sensationalist headlines can be seen in both the popular press and here at Conservapedia.
#:
#:But relativity never said anything about vacuum polarization.
#:
#:The factor "c" appearing in equations of relativity (E=mc^2, the Lorentz factor, etc.) is the calibration constant for space vs. time. While it was perceived as the "speed of light" back in 1905, that depended on the classical theory of light, from Faraday, Maxwell, et. al., at that time. Under the classical theory, Maxwell's equations were considered to be '''exactly''' correct, and light was considered to travel at '''exactly''' the speed indicated by those equations, which speed is denoted "c". The speed "c" would be better described as "that speed that all observers, even those in relative motion, will consider to be the same." The experimental basis for relativity (Michelson-Morley experiment) was that light obeyed that property. That, plus the fact that "c" appears in Maxwell's equations in a way that makes it independent of an observer's state of motion, made it clear that "c" was in fact the speed of light. But that depended on the belief that Maxwell's equations were exactly correct. But that was before Quantum Mechanics and gauge interactions. Under Quantum Mechanics, the propagation of light is determined by the behavior of photons, not by Maxwell's field equations. Of course the two results are almost identical, as is required by the Correspondence Principle. But, under the modern "Standard Model" of Quantum Electrodynamics, photons can interact with the vacuum, due to "vacuum polarization", leading to extremely tiny higher-order corrections to the equations governing the behavior of photons. This can cause photons to travel at a speed slower than "c".
#:
#:Now the situation is made more complex by the fact that models of supernova behavior indicate that the light is emitted after the neutrinos, because the neutrinos are emitted at the instant of the core collapse, and the light must wait until the effect of the collapse reaches the surface. After taking that into account, the cited article says that the extra delay for supernova SN1987A was 4.7 hours. That discrepancy is only 53 parts per trillion, and hence can only be observed in light from very distant supernovas.
#:
#:Calculating the speed of the neutrinos is interesting, because the observation is that light traveled '''slower''' than the neutrinos, even though neutrinos have nonzero mass. Since neutrinos do not participate in the electromagnetic interaction, they are not subject to the same vacuum polarization as photons. Their retardation comes only from their mass and the normal equations of relativity.
#:
#:Taking the mass of an electron neutrino as 0.25 eV (using the usual E=mc^2 formula that all scientists use for this), a neutrino would have to have a kinetic energy of about 0.025 MeV to experience a retardation of 53 parts per trillion. Since the energy of astronomical neutrinos is generally believed to be in the range of 0.5 to 20 MeV (it's really hard to measure) the expected retardation of the neutrinos from SN1987A is much '''less''' than that of the light.
#:
#:It's interesting that the issue of whether neutrinos travel faster than light actually '''did''' come up in another round sensationalist headline-grabbing articles, from an experiment at Gran Sasso, in the popular press and here at Conservapedia. The first headline was that neutrinos traveled '''faster''' than light, a claim retracted after a cable was fixed, but then reported here that someone (erroneously) had said they had traveled at '''exactly the same speed''' as light, which also violates relativity because neutrinos have nonzero mass. In any case, that discrepancy would have been several orders of magnitude too small to measure in the Gran Sasso experiment, and the discrepancy from vacuum polarization several orders of magnitude smaller still.
#''Celestial signals defy Einstein''.
#''Celestial signals defy Einstein''.
#:It shouldn't be surprising that, when Einstein died nearly 60 years ago, he didn't know ''everything'' that there is to know about spacetime. Newton didn't know everything there is to know about calculus (Hilbert spaces) or classical mechanics (Lissajous orbits), and Bohr and Schrödinger didn't know everything there is to know about Quantum mechanics (entanglement). What Einstein knew, at the time, about spacetime was how to give a precisely relativistically correct formula for how matter and energy (and momentum and stress) give curvature to spacetime, which in turn gives rise to gravity. These equations have been confirmed, with great accuracy, repeatedly.
#:It shouldn't be surprising that, when Einstein died nearly 60 years ago, he didn't know ''everything'' that there is to know about spacetime. Newton didn't know everything there is to know about calculus (Hilbert spaces) or classical mechanics (Lissajous orbits), and Bohr and Schrödinger didn't know everything there is to know about Quantum mechanics (entanglement). What Einstein knew, at the time, about spacetime was how to give a precisely relativistically correct formula for how matter and energy (and momentum and stress) give curvature to spacetime, which in turn gives rise to gravity. These equations have been confirmed, with great accuracy, repeatedly.