89
edits
Changes
Jump to navigation
Jump to search
Line 18:
Line 18: − #''Despite wasting millions of taxpayer dollars searching for gravity waves predicted by the theory, none has ever been found. Sound like global warming?'' − #:True, the ''direct'' searches for gravitational waves have not yet yielded any clear results, though indirect observations have been made (the Hulse/Taylor observations.) Before people dismiss indirect observations, recall that no one has ever seen an electron. − #:The Earth-based LIGO detectors have, so far, not detected any unambiguous gravitational wave signatures from such events as a black-hole merger. It is barely sensitive enough to find such things in the Milky Way or very nearby galaxies. It is being upgraded in a plan that should complete in 2014. It is hoped that, after the upgrade, it will be able to see these events clearly and unambiguously. − #:The space-based LISA detectors have not been built yet, and the original proposal has been scrapped because of budgetary problems. A new version, called "eLISA" has been proposed, and should be sensitive to events as far away as redshift 15. − #:Whether these experiments are a good use of money is another question, one that has no bearing on whether relativity is correct. − #::The objection has been raised that the experiments should not have been funded if scientists were going to ignore negative results. − #:::The results are only partly negative. The scientists knew all along that a certain amount of luck would be involved in finding a sufficiently strong signal within the time frame of the experiment. The failure so far does not mean that black-hole mergers do not emit gravitational waves; just that they haven't been lucky enough to find them. They will continue to search. − #:'''Update:''' Another, much more commonplace observation of gravitational wave emission has neen reported<ref>http://www.bbc.co.uk/news/science-environment-19408363 BBC article</ref>. The article suggests that, since it shows detectable gravitational waves are more common than previously thought, there is optimism that the eLISA detector, when completed, might find one source per week. − #:This has nothing to do with global warming. Line 72:
Line 63: + + + + + + + + + Line 81:
Line 81: − + − + Line 196:
Line 196: + + + + + +
Essay:Rebuttal to Counterexamples to Relativity (view source)
Revision as of 02:44, September 18, 2012
, 02:44, September 18, 2012Track a reordering on the other page (please be careful, guys!) and respond to the two new ones.
Unlike most essay pages, anyone is welcome to contribute. We ask that you abide by the usual guidelines—do not remove non-vandal, non-parody, non-libelous material without discussing it first on the talk page, or explaining after-the-fact for serious problems.
Unlike most essay pages, anyone is welcome to contribute. We ask that you abide by the usual guidelines—do not remove non-vandal, non-parody, non-libelous material without discussing it first on the talk page, or explaining after-the-fact for serious problems.
#''The orbital radius of the Moon's orbit is increasing, contrary to what Relativity predicts''.
#''The orbital radius of the Moon's orbit is increasing, contrary to what Relativity predicts''.
#:This could be a counterexample to both GR and Newtonian gravity--in both, the radius is defined in terms of conserved quantities.
#:This could be a counterexample to both GR and Newtonian gravity--in both, the radius is defined in terms of conserved quantities.
#:
#:
#:The ICFR is described in [http://www.iers.org/IERS/EN/Publications/TechnicalNotes/tn32.html this] document, dated 2003.
#:The ICFR is described in [http://www.iers.org/IERS/EN/Publications/TechnicalNotes/tn32.html this] document, dated 2003.
#''Despite wasting millions of taxpayer dollars searching for gravity waves predicted by the theory, none has ever been found. Sound like global warming?''
#:True, the ''direct'' searches for gravitational waves have not yet yielded any clear results, though indirect observations have been made (the Hulse/Taylor observations.) Before people dismiss indirect observations, recall that no one has ever seen an electron.
#:The Earth-based LIGO detectors have, so far, not detected any unambiguous gravitational wave signatures from such events as a black-hole merger. It is barely sensitive enough to find such things in the Milky Way or very nearby galaxies. It is being upgraded in a plan that should complete in 2014. It is hoped that, after the upgrade, it will be able to see these events clearly and unambiguously.
#:The space-based LISA detectors have not been built yet, and the original proposal has been scrapped because of budgetary problems. A new version, called "eLISA" has been proposed, and should be sensitive to events as far away as redshift 15.
#:Whether these experiments are a good use of money is another question, one that has no bearing on whether relativity is correct.
#::The objection has been raised that the experiments should not have been funded if scientists were going to ignore negative results.
#:::The results are only partly negative. The scientists knew all along that a certain amount of luck would be involved in finding a sufficiently strong signal within the time frame of the experiment. The failure so far does not mean that black-hole mergers do not emit gravitational waves; just that they haven't been lucky enough to find them. They will continue to search.
#:'''Update:''' Another, much more commonplace observation of gravitational wave emission has neen reported<ref>http://www.bbc.co.uk/news/science-environment-19408363 BBC article</ref>. The article suggests that, since it shows detectable gravitational waves are more common than previously thought, there is optimism that the eLISA detector, when completed, might find one source per week.
#:This has nothing to do with global warming.
#''The discontinuity in momentum as velocity approaches "c" for infinitesimal mass, compared to the momentum of light.''
#''The discontinuity in momentum as velocity approaches "c" for infinitesimal mass, compared to the momentum of light.''
#:The formulas for velocity, momentum, and mass can in fact be written in such a way that they appear to have discontinuities, just as the tangent function has discontinuities while the underlying sine and cosine functions do not. But they can also be written in a form that does not show discontinuities.
#:The formulas for velocity, momentum, and mass can in fact be written in such a way that they appear to have discontinuities, just as the tangent function has discontinuities while the underlying sine and cosine functions do not. But they can also be written in a form that does not show discontinuities.
#:The simple answer is, unequivocally, that it acts on the 'relativistic' mass. The question seems to relate to a simple misunderstanding of Special Relativity. Einstein's theories lead to the conclusion that observers in different inertial frames of reference (i.e. observers with differing, but constant velocities relative to the thing being observed) will observe different inertial masses in the body being observed. However, there is no variance in the body's mass with regard to the direction of the force. Thus to a given observer, a force in any direction will operate on the same mass. However, to a different observer, this mass may be different, although still the constant with regard to the direction of the force.
#:The simple answer is, unequivocally, that it acts on the 'relativistic' mass. The question seems to relate to a simple misunderstanding of Special Relativity. Einstein's theories lead to the conclusion that observers in different inertial frames of reference (i.e. observers with differing, but constant velocities relative to the thing being observed) will observe different inertial masses in the body being observed. However, there is no variance in the body's mass with regard to the direction of the force. Thus to a given observer, a force in any direction will operate on the same mass. However, to a different observer, this mass may be different, although still the constant with regard to the direction of the force.
#''The observed lack of curvature in overall space.''
#''The observed lack of curvature in overall space.''
#:What? Is has been observed
#:Spacetime has very definite curvature near any massive object—this is what makes gravity work. The '''global''' curvature of spacetime is an altogether different issue. Whether the average global curvature is zero has consequences for cosmological theories, but it has essentially no effect on the curvature that keeps the Earth in its orbit. If it did have an effect, the issue would have been settled long ago.
#''The universe shortly after its creation, when quantum effects dominated and contradicted Relativity.''
#''The universe shortly after its creation, when quantum effects dominated and contradicted Relativity.''
#:We're still working on a quantum theory of gravity; this isn't so much a counter-example as saying that (classical)GR isn't valid in that domain.
#:We're still working on a quantum theory of gravity; this isn't so much a counter-example as saying that (classical) GR isn't valid in that domain.
#''The action-at-a-distance of quantum entanglement.''
#''The action-at-a-distance of quantum entanglement.''
#:Special Relativity only forbids the transmission of matter, energy or information at a speed faster than light. There are plenty of other things that can move faster than light. Consider a laser on Earth which is rotating on a pivot, whose light shines onto the hull of a satellite 200,000Km away (2e8 metres). If the laser rotates at a sedentary one revolution ever four seconds, the speed of the laser beam's tip crossing the satellite's hull is 3.14e8 metres per second - faster than the speed of light. However, this is not a transfer of information. Any information is travelling from Earth to the satellite, obeying the universal speed limit. Similarly, the only information that can be transmitted by the quantum entanglement of two particles is from the originator of the particles to the two observers, not from one observer to another. Faster than light transmission of information using quantum entanglement has never been observed, nor has even conceived how such a mechanism might work.<ref>http://curious.astro.cornell.edu/question.php?number=612</ref>
#:Special Relativity only forbids the transmission of matter, energy or information at a speed faster than light. There are plenty of other things that can move faster than light. Consider a laser on Earth which is rotating on a pivot, whose light shines onto the hull of a satellite 200,000Km away (2e8 metres). If the laser rotates at a sedentary one revolution ever four seconds, the speed of the laser beam's tip crossing the satellite's hull is 3.14e8 metres per second - faster than the speed of light. However, this is not a transfer of information. Any information is travelling from Earth to the satellite, obeying the universal speed limit. Similarly, the only information that can be transmitted by the quantum entanglement of two particles is from the originator of the particles to the two observers, not from one observer to another. Faster than light transmission of information using quantum entanglement has never been observed, nor has even conceived how such a mechanism might work.<ref>http://curious.astro.cornell.edu/question.php?number=612</ref>
#:
#:
#:The cited article never mentions relativity or the possibility that relativity is wrong. In fact, the entire discussion is in the context of black holes. The second study was about a black hole at the center of a galaxy apparently wandering out of place. The hypothesis is that a merger of two galaxies was involved, and "the theoretical prediction is that when two black holes merge, the newly combined black hole receives a 'kick' due to the emission of gravitational waves ..." Gravitational waves are, of course, a specific prediction of general relativity.
#:The cited article never mentions relativity or the possibility that relativity is wrong. In fact, the entire discussion is in the context of black holes. The second study was about a black hole at the center of a galaxy apparently wandering out of place. The hypothesis is that a merger of two galaxies was involved, and "the theoretical prediction is that when two black holes merge, the newly combined black hole receives a 'kick' due to the emission of gravitational waves ..." Gravitational waves are, of course, a specific prediction of general relativity.
#''Scientists are unable to explain a June 2012 cluster of earthquakes in Ireland.''
#:This one is even more absurd than the one above about tides. We cannot fathom why anyone would think earthquakes are a counterexample to relativity.
#''Apparently, the equations of General Relativity do not apply to the motions of extra-solar planets.''
#:This refers to a recently discovered planetary system in which another star is closer than had previously been seen in such a system. Systems involving two stars and a planet constitute the "three body problem", which has never been solved analytically. But if only one of the objects is massive, such as the Sun, the system can be stable for all practical purposes, which is why the solar system is effectively stable even though it is a many-body problem. But two stars make the system much more problematical. In the past, such systems have had the other star far enough away that it has essentially no effect. The Gamma Cephei system is different, and scientists are eager to analyze it in detail. They are frustrated in this by the extremely scant data about the planet's orbit, since that information has to be gleaned from tiny spectroscopic shifts (in only one dimension!) of the two stars.
#:
#:The effect of Relativity on this is, of course, the precession of the "perihelion" due to the effects of General Relativity. From the information that has been gathered, the precession should be about 1.14 arcseconds per Earth century, or about 1/37<sup>th</sup> that of Mercury. The precession of Mercury was established with accurate visual observations. Measuring something 1/37<sup>th</sup> as large, from the Doppler shift in spectroscopic measurements, is utterly beyond current technology. Other than that, there is no reason to consider relativity. Classical mechanics will do just fine.
== References ==
== References ==