Relativity Discussion Forum

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Question by Craig Gordon
If I have a very long rod, why can't I jab one end and cause an instantaneous faster-than-light reaction at the other? Actually, any length rod - the same question applies.

As far as I am concerned, this is indeed what happens. The jab may not immediately appear to the full extent at the other hand (the rod can not be 100% rigid, as the inertia of the atoms leads to a delay of the response), but to some degree (even though it may be infinitesimally small) there will be an instantaneous reaction at the other end (see also my page regarding Retarded Forces in this respect).

Comment by Peter
In the diagrams in advanced physics texts the idea of parallel lines meeting if the geometry is on the surface of a sphere i.e. non-Euclidean there is a logical error.The only time lines passing through the poles by converging to such a point could be deemed parallel is at their intersections with the equator. At all other points the are converging. Thus, they can only be considered 'parallel' at one point but it needs two points to define a line. The argument about parallel lines crossing in non-Euclidean geometry therefore means that either the definition of a line must be modified, but the current definition is essential to the argument, or there is some logical error in the argument.

I understand what you are saying, and your argument is basically correct, but it really all depends on your definition of 'parallel lines': as you said, 'great circles' on a sphere are only parallel in one point (actually, two points) and also cut each other in two points. They can obviously not be parallel everywhere. But if you consider circles other than 'great circles', then these can be parallel everywhere (e.g. latitude circles). It should be obvious that on any kind of surface you can draw a parallel to any kind of line just by drawing a second line that keeps the same distance to the first one everywhere.

However, these are really only mathematical issues that arise on the surface of objects assuming that one is constrained to that surface. In this case the shortest distance between two points is in general not given by a straight line. However, if you are not constrained to the surface, then you can still connect any two points by a straight line (e.g. by correspondingly drilling through the object). So in our 3D-world, the shortest distance between two points is always a straight line (and parallels are thus parallel everywhere and never meet).

Comment by Alan Chambers
I read your attempt at a critique of General Relativity, and some related articles. It is plain to me that you do not really understand what a scientific theory is.

Calculations made with Einstein's theory of gravity agree with previous experimental observations to a far better degree than, for example, Newton's theory. This makes the theory robust. It is a solid, simple and self-consistent explanation of what we already know. Better yet, the theory also makes a number of falsifiable predictions which can be (and have been) experimentally tested - the predictions were verified to a very high degree. This makes the theory reliable. Making successful predictions means we can be confident that the theory is a good model of gravitation, rather than just some cobbled together explanation of earlier observations only. Other more complicated theories have been proposed, but Occam's razor tells us to choose the simplest model until a counterexample is found. Please direct me to literature on counterexamples to Einstein's theory.

It simply does not matter whether or not one believes that curved space-time is a valid (whatever that means) description of the real (whatever that means) world. Is the motion of objects in free fall caused by them following geodesics in a curved spacetime? Or does it just look that way, but is actually caused by something else? What's the difference?

You suggest that space-time is a mathematical abstraction that has no basis in reality. Please tell me: what is reality? Perhaps little fairies push all the atoms around in such a way that their motions are consistent with Einstein's predictions for free fall in a Riemannian manifold. Such a theory could be quite robust, if rather complex, but I doubt that it would make any novel predictions that were subsequently verified.

What is your basis for arguing that gravity must be similar to electrostatic interaction? It seems to me that you just randomly pluck this out of the air because the accelerations between charged objects depends on their masses, but the strength of the force does not. I would be interested in any literature you know on what you might call "gravitational charge". It doesn't seem to me that gravity and electric charge should necessarily have a similar description. Your argument is a non-sequitur.

Your argument that the bending of light rays is an "unallowed generalization" is simply nonsense. Such a prediction is entirely consistent with the notion that space-time is curved. Unforced motion is always locally in straight lines (in a Euclidean sense) because space is locally flat, but this straightness is not preserved globally. A light ray moves along a line which is always locally straight, but is globally bent. It is worth noting again that this prediction has been experimentally verified. I'm not aware of any alternative theory that makes this prediction and calculates the deflection so precisely.

As an aside, it is also surely obvious that the energy contained in "immaterial and massless" photons should be included in the stress-energy tensor which curves space time. A passing photon presumably creates its own (very, very small) wrinkle in space-time.

I would be interested in how you explain gravitational time-dilation, which is also experimentally confirmed. Don't bother to point me at your comments on gravitational lensing, GPS or special relativity. I've read them already.

You make some vague claims and hints about other possible explanations for gravity and physical phenomena such as light-bending, which seem more plausible to you, but do not offer any worked out theories, consistent explanations or falsifiable predictions. I am led to conclude that you simply reject Einstein's theory because you do not understand it. It is ludicrous to reject mathematically precise explanations of phenomena because they are counter-intuitive. Our minds evolved to deal with surviving in the 3-dimensional, low-speed world of the East African plain. Consequently, we are not really well-equipped for thinking in higher dimensions or dealing with relativistic effects. Our inability to make these phenomena into "common sense" has no bearing whatever on their validity. What makes electrostatic attraction any more obviously sensible than space-time curvature. Nothing. You're just used to it.

It is worth saying that sooner or later some other theory will come along which has a greater domain of applicability, such as dealing with quantum effects. That theory will naturally agree with Einstein's calculations and predictions at the macroscopic level but might involve a completely different model which has nothing to do with curved space-time. It may make some different predictions about as yet unobserved phenomena which Einstein can't explain. It will be interesting.

First of all, let me say that I generally welcome any critical comments regarding the content of my site, as they only force me to further clarify the corresponding points and thus to improve my articles. In fact, quite a few pages on my site have indirectly arisen from critical discussions that I had with other people in the first place (by email or in some forums or newsgroups). So you can generally speaking assume that the validity of my arguments is, as far as I am concerned, already tested to a certain degree (although of course there is always room for improvement). But let's get back to your specific comment:

your view that people who are critical of Einstein's theories would fail to understand them is actually typical of Einstein's followers, but it does not in any way address the criticism:   as I have pointed out on my Relativity and Cosmology pages (for those who haven't read this yet), the idea that 'space-time' (i.e. physically nothing) could affect objects is, as a physical theory, conceptually and logically inconsistent. Objects can only be affected by other objects (via the fundamental interaction forces). What's more, it is also logically inconsistent to assume that a fundamental force could depend on the gradient of some potential function (in this case the curvature of space-time) as it implies a non-local nature (if one assumed that the acceleration a(s) at location s would depend on the gradient of some function f(s), then this would imply that a point mass at location s would also be affected by the location s+ds as the gradient is defined as (f(s+ds)-f(s))/ds (with ds being infinitesimally small but different from zero)).

If objects or light signals follow curved paths, then this is due to some interaction with matter, not due to the properties of space-time (the latter must by definition be Euclidean, as (ignoring the paths of objects) you can connect any two points by a straight line). If we would be physically confined to a curved space like one is confined to the curved surface of a sphere, then we simply couldn't connect any two points by a straight line. The fact is that, by definition, we are not confined to any space curvature (neither is one actually confined to the curved surface of a sphere, as we can drill through it and thus connect any two points by a straight line).

This should make clear that the concept of a non-euclidean metric of our 3D-space (i.e. a curvature of space(time)) is conceptually flawed from the outset. It is as flawed as the 'equation' 1=2, so it doesn't really make any sense to try to support it by observational evidence, as this should be a matter of principle and not of numerical coincidence (nonetheless, it is probably noteworthy to point out here that the initial acceptance of General Relativity came about under rather dubious circumstances, namely the questionable data analysis by Leverrier and Newcomb regarding Mercury's perihelion precession, and Eddington's questionable analysis of the 1919 eclipse data for the bending of starlight by the sun ; and at a closer look, more recent 'confirmations' of GR may not fare much better).

This all doesn't mean though that I necessarily reject the idea that light paths can be deflected by masses, it is only the interpretation that this would be due to a space(time) curvature which is unacceptable (as per above arguments). It is in my view implausible though, as light has no mass but is of an electromagnetic nature and thus is much more likely be affected by electric and magnetic fields. And yes, contrary to what you are implying, my corresponding alternative Plasma Theory for Light Bending is falsifiable (or rather verifiable): you just need to measure the deflection from a body in space that hasn't got a substantial plasma atmosphere (e.g. the moon or asteroids, but a suitable planet would probably do as well). My theory predicts no deflection then (or at any rate one substantially smaller than GR would predict).

Comment by Ron Harrison
I am a retired dynamicist, the first part of my career was in aircraft design and the second part was as senior lecturer at City University, London. I have published books on dynamics, and in Advanced Engineering Dynamics I included a chapter on Special Relativity. I felt that General Relativity was far more complex than is required to predict known phenomena, so, I developed a new approach to gravitomagnetics with force relegated to a defined quantity. Attached is a summary of the basics of the approach.
Further details, including the simple formula, are to be found in Full development is in my book "Gravity, Galileo to Einstein and Back". (Newtonian Force, Slave or Master). ISBN 1-58112-932-7.

I had already a couple of discussions with people proposing theories very similar to yours. First of all, even ignoring the logical and mathematical inconsistencies both in the Special and General Theory of Relativity, there is as such no obvious reason why gravity should in any way formally behave similar to electromagnetism. Even though this is of course no stringent argument against it, there is a major problem with this analogy:   in the same sense as you need a charge current to produce a magnetic field, you would need a mass current to produce the gravitomagnetic field. The point is that in order to define the current in electrodynamics you need two charges moving relative to each other, because otherwise your current and hence your field would depend on the state of motion of the observer, which is not possible as the velocity appears also explicitly in your equation (I have already criticized Maxwell's Theory for not recognizing this on my home page under Maxwell's Equations. ). You would therefore only be able to define your 'mass current' if you have two different 'charges' of mass that move relative to each other. Given the very different appearance of gravitational and electrical phenomena in nature, I think it is safe to say that this can be excluded. So it is probably not surprising that gravitomagnetism has experimentally not been confirmed so far (as you may know, Gravity Probe B was designed to confirm the existence of the so called 'frame dragging' in General Relativity (which contains gravitomagnetism implicitly as well), but failed to do so (after a new data analysis, the Gravity Probe B team claimed very recently on their website that evidence for frame dragging has been found, but I would be very sceptical about results that have only been obtained after years of massaging the original data; in any case, this is an unconfirmed claim which has not been officially published yet)).

Ron Harrison (2)
The most important point is that my one simple equation gives the relative acceleration between two bodies due to gravity as a function of the sum of their masses, their separation and, further, their relative velocities. Therefore the comment on the motion of the observer is redundant. If the velocities are small compared to that of light then the equation reverts to the Newtonian form. Application of the equation gives results which agree with the measured value of the precession of the perihelion of Mercury and the deflection of light past a massive body. It agrees exactly with the predictions of General Relativity. It also works for several other observations, but it is much easier to apply than General Relativity.

The comment on mass current is also irrelevant because electromagnetic effects can be generated by isolated moving charges. In gravity, since no negatively charged bodies have been found, the Newtonian static gravity cannot be neutralised and in most cases this is large compared to the non-Newtonian part. In current carrying wires the electrostatic component is neutralised.

Gravitomagnetic (for the want of a better term) effects have been observed, such as Mercury's precession, as well as the others mentioned in . My equation does yield the same form of equation for the motion of a free gyroscope in space as that of L. Schiff. However, I predict a slightly smaller magnitude than quoted, this makes it even more difficult for the Gravity Probe-B data analysis.

Reply (2)
Yes, your equation (which is just stated without a derivation) seems to take v as a relative velocity, but it does actually not mirror the magnetic force term in electrodynamics (which it should do according to the Wikipedia article about Gravitomagnetism)). The latter is linear in v (the Lorentz force is proportional to vxB, but your gravitomagnetic force term is quadratic in v. Such a force term would have very odd properties (for instance the associated 'gyroradius' R would be independent of velocity, as the centrifugal force is proportional to v2/R).
The point is that in vxB, B also contains a velocity, but that is a different velocity, related to the current producing the magnetic field, not the velocity of the test particle. And there should be two different velocities for the gravitomagnetic effect as well, because otherwise you could not define the rotation of the central mass (which is unrelated to the velocity of the test mass) (see for instance this reference). And then, as I said, you run into the problem that the 'mass current' would require two different mass 'charges' in order to be frame independent (which of course would be paradox anyway, as it would neutralize the net mass to zero).

By the way, you state that your formula produces correct results for instance for Mercury's perihelion precession, but I have actually nowhere encountered an explicit numerical evaluation of your formula in this respect in your paper. This in itself is not very confidence inspiring.

Question by Bruce Harvey
The radio signals to and from space probes show a time delay when passing close to the sun which it is said supports General Relativity. Gravitational potential is said to curve space-time making the path longer.
If there is no such thing as space-time which might become curved, how sympathetic are you to the idea that gravitational potential affects the permittivity and permeability of space slowing the speed of light?
This would still allow for the local speed of light along the path of the signal to remain equal to the numerical universal speed of light because rulers and clocks used to measure the local speed would be affected in the same way as the radio waves. But when a non-local measurement was made calculating distances from the orbits and measuring time with earth-bound clocks, the speed of light appears slower.

Well, according to Relativity, the time delay due to the slowing of the speed of light near masses is actually the dominant effect here (Shapiro delay), not the space curvature. Generally speaking however, I would consider a gravitational interaction with electromagnetic waves (which are after all massless entities) as implausible. I have in this sense suggested that it is in fact the electric field associated with plasma masses that is responsible for the observed effect (see my page Plasma Theory of 'Gravitational Lensing' of Light.

Comments by James Pollock
As a physics student currently studying relativity, I was fascinated (and ultimately extremely distracted from exam revision) reading your critique of SR and the comments of other people regarding it. While you are obviously far more knowledgeable on the subject, I have one or two problems with your ideas and reasoning.

1) While you will obviously claim that people are merely blindly following Einstein's theories, I imagine his ideas and reasoning have come under much scrutiny over the last 100 or so years. I struggle to believe that so few people have spotted the flaws you describe. If they are as fundamental as you describe surely his theory would have been debunked years ago. Have you brought your ideas to the attention of experts in the field of relativity? Surely they will quickly notice the errors of their ways.

2) There is overwhelming evidence that Einstein was correct. While you dispute SRs role in muon decay, how can you reconcile the fact that the deviation from the expected time for a particle to decay is proportional to its speed, as witnessed in experiments by particle accelerators. You also seem to claim that objects can, in fact, travel faster than the speed of light. However, as particle accelerators have shown, as we apply more and more energy to a particle its speed tends towards the speed of light.

3) A lot of you evidence points towards the absurd conclusions that SR would give. However, having a variant speed of light would create more absurdities e.g. seeing events before they happened.

4) The twins paradox doesn't seem to me to be an issue with SR. It deals with one twin accelerating away from the other and then returning. This acceleration means that we are not dealing with inertial frames, which I believe is a requirement for SR. Surely GR would be better suited to dealing with this problem?

5) Also, I believe that your thinking is flawed with regards to dealing with multiple time frames, and this seems to be the source of disagreement of many of the ideas put forth. With the idea of comparing the two clocks moving at the same speed but in opposite directions you say this will clearly show no time difference has occurred. You seem to be thinking about this not from the reference frame of either of the clocks, but from a third reference point stationary to this event. As the two clocks are travelling at equal speed away from you, the time dilation will be the same and you will see the time of the clocks as the same. Considering events from the reference frame of one of the clocks yields a different result, however, and I believe you are missing the importance of the different reference frames. Both clocks would see the time on the other clock move slow, and there is no contradiction there when you consider each reference frame separately. Both are correct for their particular reference frame.

As I stated previously, I am new to the subject of relativity. I can only apologise for my ignorance on the topic and the widely inaccurate claims I may be making due to my ignorance.

First of all, I always welcome any questions or criticism regarding the content on my site as it only helps me to improve and clarify my arguments. So there is no need to apologize. In this case, your questions may be basically already answered in one way or another on my website, but I am happy to respond to them again directly:

1) Well, 100 years is not such a long time in the history of science. The geocentric system of the universe survived for 2000 years even though the heliocentric idea was around for almost as long. Science just doesn't always develop according to the scientific 'truth' but one also has to take the power of social and psychological 'laws' into account. History has shown often enough that in this sense established views and systems of thoughts (even if they are wrong) are difficult to shift. This holds especially if it comes down to questions of conceptual and mathematical logic. Many scientists and philosophers (and even mathematicians) are actually not so well trained in formal and applied logic, and it is not so difficult to deceive them with logically flawed concepts and ideas. In this case, it was just not realized that the usual concept of 'speed' (which implies a velocity dependent transformation) is logically inconsistent with the invariance of c. This together with a sloppy attitude towards mathematical rigour not only led to the Theory of Relativity but also made the latter look acceptable despite obvious paradoxes arising from the logical and mathematical flaws. I had simply the time and motivation to get to the bottom of these paradoxes and analyse the derivation and application of the Lorentz transformation in all mathematical and logical details.
I realize that it may be asking a lot for my arguments to be accepted by experts in Relativity, so for the time being I am just offering them to the wider public (i.e. anyone sufficiently interested in and familiar with Relativity) for discussion.

2) If someone told you that there is overwhelming experimental evidence that 2+2=3, would you believe him? I don't think so, because you know that according to the axioms of mathematics 2+2=4. Likewise, on the basis of correct logic and math, Einstein's conclusions can not be correct. Corresponding experiments have to be interpreted differently. The lifetime of a muon could for instance depend on the magnetic field it is exposed to (which is proportional to its velocity in a synchrotron). And the fact that the speed of light can not be exceeded could be due to the circumstance that the electro- and magnetostatic forces are actually velocity dependent (as suggested on my page A Newtonian Relativistic Electrodynamics. These are only suggestion that come to mind without being much of an expert in synchrotron physics. There may be other ways to interpret the data if one is more familiar with the technical details in this respect.

3) I have not been suggesting a variant speed of light, just a different interpretation of what is an invariant speed (or indeed a speed in the first place), namely that the time to travel from the source to detector depends just on the distance between them at the moment the signal is emitted, but not on their relative velocity. This would lead to two detectors in the same place not necessarily registering the signal at the same time (depending on where they were when the signal was emitted), but this is not a logical paradox, merely somewhat unusual from the viewpoint of everyday physics (and you would expect something unusual from the fact that the speed of light does not depend on the state of motion of source or detector).

4)+5) The time dilation in SR depends on the velocity, not on the acceleration. You could make the period of acceleration in practice arbitrarily small or indeed avoid any acceleration altogether as in the thought experiment on my page Time Dilation and Twin Paradox Debunked. SR clearly claims that in a (uniformly) moving reference frame clocks would go slower than in a stationary one. This is obviously logically impossible as it would lead to a (non-resolvable) paradox in symmetric cases like the suggested one: the observer in system A would conclude that the clock of system B goes slower and vice versa, but clearly one can not have tA>tB and tB>tA at the same time.

Comment by Cuthbert Simpkins
I really enjoyed reading your revelation of the mathematical inconsistencies in Einstein's work. When I read his derivation before I missed the point you make about the assumption that relationships defined only in a given region can be added and subtracted from a relationship defined in a totally different region. Even though Einstein's derivation is incorrect there are other derivations of the Lorentz factor that seem ok. I like the one by Yakovenko written in matrix form. But even with a good derivation your point that electromagnetic energy and matter such as a bullet are inherently different is very appealing. Basically you are saying that a Gallilean transformation cannot be applied to light while it can be applied to a bullet. Then you go further to state that there is no need for a transformation if one simply accepts the fact that in any time frame light will always have the same velocity and that a transformation is unnecessary and leads to incorrect conclusions such as time dilation and space contraction. My next question then is how do you explain the constancy of the speed of light? It seems as though you simply take it as a given. What is your model of electromagnetic energy?

The reference you gave does not derive the Lorentz transformation. It shows that if you assume a velocity dependence of the transformation between two coordinate systems, the symmetry principle for space and time leads formally to a number of different solutions, one of which is the Lorentz transformation (one of the others is the Galilei transformation). This treatment is very much reminiscent of the one that Levy and Leblond gave already in 1976. If you look at page 275 (right column) in that paper, then you see that there are also the three different solutions mentioned. The point is that in order for the Lorentz transformation to be acceptable, one must make the further a-priori assumption that there is a limiting velocity v=c for all objects, as otherwise the term under the square root would become negative. However, there are no theoretical grounds for such a limiting velocity.

The point is there can not be a mathematically correct derivation of the Lorentz transformation, because, as I have shown on my page Regarding the 'Light Sphere' Derivation of the Lorentz Transformation the LT is itself inconsistent with the principle of the invariance of c. The latter requires that if the sign of the coordinate of a light signals is reversed in one frame, it must also reverse in any other frame. This rules out any transformation of the form x'=a.(x-vt). The only possible form is x'=a.x.

And yes, the principle of the invariance of c is strictly speaking an observational, i.e. given, fact. On my page regarding the Speed of Light, I have however given a theoretical argument for this as well. I quote: "if one accepts that light is an electromagnetic wave, it is indeed a theoretical necessity: a lightwave can not possibly require a physical carrier medium because otherwise it could not propagate through empty space; on the other hand, without an 'ether', the speed of light has to be constant with regard to source and receiver or otherwise it would be completely undefined. The point is in fact that a light wave needs no carrying medium as it carries itself (to be more precise, according to Maxwell's Equations, the electric wave carries the magnetic wave and vice versa; it is somewhat ironic that Maxwell himself did obviously not realize this as he believed in the ether theory and a positive outcome of the Michelson-Morley experiment)".

And for electromagnetic waves, the concepts of energy and momentum are in fact not applicable (see my page Energy and Momentum Conservation Laws in Physics for more). So there is not only no need to have a model for electromagnetic energy, but such a model would in fact be strictly speaking flawed (even though it may be a an appropriate working model in average situations).

Comment by Libor Striz
I have noticed your page Global Positioning System (GPS) and Relativity , where you claim the relativity effect on GPS is not as big as often thought ( 38 microseconds equivalent to 12 km daily distance cumulative error).
With this I agree, but I do not agree with the small residual error of 0.8 cm and with the claim that it does not accumulate.

The GPS receiver position calculation has 2 parts:
1) Trilateration providing distances and time.
2) Ephemeris based satellite position calculation.
We both agree that trilateration, providing distances to satellites and sat time to receiver, is invariant to the satellite clock error if the error is the same. But trilateration relies on reference points - satellite positions, that cannot be provided by trilateration. It is calculated from the GPS satellite and the ephemeris. But uncorrected GPS satellite clocks would together with the ephemeris provide the wrong time to receiver. If the time is wrong, it results in wrongly calculated satellite position. And during 38 us (the daily time drift) the satellite moves about 15 cm, that makes about 4.5 meters per month if not corrected.

Yes, my argument assumes the satellite positions to be known exactly, i.e. I am just considering the direct effects of any collective clock drift on the trilateration. And as you seem to agree, a collective drift of all satellite clocks of 38 us per day would only lead to a (non-accumulating) positional error of about 1 cm.

I agree though that on the basis of such a clock drift, the calculated satellite positions would drift as well (by about 5 m/month as you mentioned), but if you have a look at chapter 4.6 of the official technical documentation of NAVSTAR (GPS) then you find that the accepted ephemeris error is up to 8m anyway (the clock drift is in fact kept within 1 ms, which indeed translates into a positional error of 5 m).
But in any case, there is nothing that could in practice produce the frequently claimed positional drift of about 12 km/day.

Libor Striz (2)
There is one not yet discussed effect in our conversation:
If the orbit parameters differ from the nominal/planned ones ( general rule of real life ), the SR/GR effects will be slightly different to the expected values. Then the time drifts of the satellites will have some random distribution around the collective drift value. On the one hand this difference will be very small, compared to the collective drift. On the other hand the primary error 38 us/day => 12 km/day is now not yet fully compensated, having an original value about 5 orders bigger then the error of "satellite position = ephemerides(time) "

Reply (2)
Yes, obviously the orbital parameters (height, speed) will not be exactly identical, but a) this will only lead to a clock drift between two satellites orders of magnitude smaller than 38 us/day => 12 km/day , and b) the clocks are synchronized anyway as often as required to keep the difference within 20 ns (as stated in the reference I gave above), so any potential accumulation would just be an academic issue here. You can indeed reverse the argument: the fact that the satellite clocks are being synchronized so frequently shows that it just is not possible to fully model the clock drift (whether it is caused by relativistic effects or anything else).

Comment by Carel van der Togt
Everyone heard that in CERN experimental physicists measured that particles traveled faster then the speed of light. The excuse of theoretical physicists for this is that 'Time Travel', in the past declared impossible, might be possible.
Again Theoretical Physics tries to conceal their incompetence. Do not be deceived this time. Read the chapter Incompetent Science Part I. You will find all the proof you need to disqualify the Relativity Theory. Only high school physics/math and an open mind are required to realize Theoretical Physics is false for over 100 years.

Time travel is not possible for logical reasons, namely because 'time' is defined by change as such, irrespective in which direction the change occurs (after all, one does not grow younger by watching a film running backwards) (this is discussed in some length on my Philosophy of Science discussion page). Even if faster-than-light travel is possible, this circumstance does not change, so it has nothing to do with the validity of Special Relativity.
The faster-than-light neutrino speed measured by CERN's OPERA experiment only confirms the finding I published on this website that the derivation of the Lorentz transformation is conceptually and mathematically flawed. The limiting speed of c that is observed for instance in particle accelerators for charged particles could be explained by velocity dependent electromagnetic forces, but neutrinos have no charge, so this would not apply to them.

I generally sympathize with your critical stance regarding the state of theoretical physics, but it is important to get to the root of the issues (like in this case Einstein's mathematical errors when deriving the Lorentz transformation). Attacking the symptoms rather than the causes does not resolve any issues.

Comment by Dejan Vrbat
I feel somehow obligated to point out a fundamental flaw in these mechanical stop-clocks: they can not be used as a stable link between the two systems that can affect the clocks simultaneously because solid matter is not a separate form of existence from energy. It is held together by electromagnetic fields and we have long known at what speed they propagate through a certain medium. When a force is applied on a certain part of any material object, like an iron bar, in order to move it, it has to move every single atom in the bar. Additionally, it is spread through the bar by affecting the electrons in their shells trying to "push them closer" - this is counterbalanced by spreading the initial force on the surrounding electrons orbiting the atoms in the vicinity. The force is therefore transmitted via electromagnetism, and the simultaneity implies INSTANT propagation of the applied force. Not only that, but from what I could gather from this small animation here on the page, it would also need some time for the signal to cross the distance between the point of affectance and the clock itself. It will not, therefore, provide anything drastically different than what is already used concerning the actual effects.

As mentioned on the page you are referring to, the signal propagation times are irrelevant here. The crucial feature of the suggested thought experiment is its absolute symmetry, regardless of whether the signal travels instantaneously or not. It is only required that the two systems are physically identical in all respects. This guarantees that the twin paradox can not be resolved by means of claiming that one observer is privileged because of some asymmetry in the setup.

Dejan Vrbat (2)
It is my position that, regardless how thoroughly thought out and exotic, thought experiments, as such, cannot 'debunk' anything. If you can come up with an actual experiment, using the method proposed, carry it out, and if it yields the results you predicted, then and only then a certain theory can fall. TR is often mistaken for a Law, which is absurd in and of itself, since nobody proved neither its correctness nor falseness. There are only indications that it MIGHT be correct, but same as you, me and countless others, all those circumstantial 'evidence' can be interpreted differently. The only sure way is developing faster and faster spacecrafts, whose speed is comparable or exceeding that of light in a vacuum.

Reply (2)
Experiments are there to test theories, but a theory that is in itself logically inconsistent (like the claim that moving clocks (as such) run slower) does not even qualify as a theory, so it does not make sense to actually do this experiment; the 'theory' is debunked by the thought experiment alone (after all, if somebody claimed that 1=2, you would not need to do an experiment either to prove it wrong, it is evident from the axioms of mathematics alone).

Question by Rob Wright
Good to read your responses to many peoples understandable queries, however you keep re-stating the dogma of the constancy of light velocity in any frame of reference, eg by saying "only separation distance at moment of emission determines travel time" etc. Doesn't this assumption inevitably lead to logical problems, and at least re-definition of what we mean by "distance" and "time" so that they become very difficult to work with? This leads to the main question: why do we still want to believe that light travel (un-distorted by any physical forces which may operate) cannot be treated as any other moving object through a vacuum?

The answer is, light does not consist of objects. There is nothing physically moving here. When you see a light, the atoms in your eye just respond to something that happens in the light source (albeit this is a delayed response). Problems only arise when you assume (like Relativity does) that light consists of moving objects. And Relativity then indeed has to re-define the units of distance and time. There are no problems at all if you define the speed just by the separation distance at the moment of emission and the travel time.

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