Frankly, I hesitated whether to reply – relativity seems to have been cursed to be under a constant attack. As a rule those who criticize it do not see the whole picture – they pick up only individual relativistic results. I know this even from personal experience – for twenty years all letters/papers claiming to have “finished” relativity sent to two departments (where I worked) have been regularly forwarded to me. The reason I decided to reply now is the slim hope that what I will write below might be helpful to some of the people who have reservations about relativity.

Let me state my view. Relativity is the most profound theory known to humankind (quantum mechanics is still an incomplete theory). It is not only correct – it might sound surprising to some but relativity could and should have been discovered much earlier (if I find some time I will publish a long delayed book that explains not only this).

It is true, however, that the major source of confusion is relativity itself. It lacks conceptual clarity. The math is OK, but the rest (yes, there is “the rest” in relativity; a physical theory is not only math) is either silence or almost a complete confusion. Here is an example – one of the problems I love to explain when I teach relativity.

“Reference frame S’ moves in the positive x direction with respect to reference frame S. The clocks in S and S’ are synchronized at t = t’ = 0 the instant the coordinate origins O and O’ of the two frames coincide. At this moment a light wave is emitted from the point O = O’. In S it is observed that the light wave front is spherical with a radius r = ct; the center of that sphere is at O. Find the shape of the light wave front in S’. Is it also a sphere whose center is at O’? If so, does this lead to a paradox? If not, does this lead to a contradiction with the principle of relativity?”

The principle of relativity requires that an observer in S’ should determine that the center of the light sphere is at O’. Applying the Lorentz transformations confirms this. But our everyday experience is telling us that there must be something totally wrong here – the center of the light wave cannot be at two different places. The only explanation you can find of this apparent paradox is the following: the wavefront of the propagating light sphere constitutes a set of simultaneous events and since simultaneity is not absolute S and S’ have different sets of simultaneous events and consequently DIFFERENT light spheres.

That’s the explanation. Are you satisfied? I doubt. That explanation is merely shifting the paradox from that specific case to the relativity of simultaneity itself. If the relativity of simultaneity were conceptually explained then the above paradox would be explained as well. Try to recall in how many books you have read that relativity of simultaneity means that two observers S and S’ in relative motion have DIFFERENT 3D spaces (since our 3D space is the set of points at a given moment of time). However, S and S’ can have DIFFERENT 3D spaces ONLY if reality is four-dimensional. With this in mind the above example becomes perfectly clear: (i) our intuition is correct that a SINGLE light signal/sphere cannot be different for different observers – the light signal is represented by a 4D light cone (ONE cone) in spacetime; (ii) relativity is also correct that different observers in relative motion have different 3D spheres – the 3D spaces of S and S’ cut the 4D cone at DIFFERENT places (the different cross-sections are different 3D spheres). If the 4D light cone and the 4D spacetime were NOT real, S and S’ could not have different light spheres and there would be NO relativity of simultaneity.

Another example that requires a lot of explanation is the relativistic increase of the mass. Here is what E. F. Taylor and J. A. Wheeler write:

1. “No mass change with velocity” (Exploring black holes: introduction to general relativity, 2000, p. 1-13).

2. “Is the mass of a moving object greater than the mass of the same object at rest? No. It is the same whether the object is at rest or in motion; the same in all frames” (Spacetime physics: introduction to special relativity, 2nd ed., 1992, p. 250).

As you see it is not necessary to reject relativity to get the mass constant – even such relativists as Taylor and Wheeler argue that there is “no mass change with velocity”. In my view the very fact that even such professionals can be confused is a clear indication that there is something really wrong with the way relativity is presented. Taylor and Wheeler’s arguments are correct but they only prove the invariance of the proper/rest mass; nothing more.

The relativistic increase of mass is closely related to inertia. This is one of the reasons why I have been devoting so much time to the classical electromagnetic mass theory; it predicted BEFORE relativity that mass increases with velocity yielding the correct velocity dependence.

To those who suspect that relativity is wrong I will take the liberty of saying this. Do not try to explain new results in old terms (especially in terms of our everyday experience). All attempts to apply old concepts to a new territory appear to be doomed to failure. History of science never goes backwards. I believe that our generation can disprove what Hegel said – that history teaches us that no one learns from history.

In this connection I cannot avoid commenting on the ever existing attempts to regard the aether/vacuum as some kind of fluid in which mechanical (pressure) waves that explain everything propagate. In addition to all arguments against such attempts consider this one as well – the vacuum/aether is not 3D; in relativity it is 4D. Relativity does not say that aether does not exist; what does not exist in relativity is a 3D aether. A 4D aether rather resembles David Finkelstein’s crystalline structure. That is why I feel that a lot of time and efforts are being wasted in any attempt to regard the aether as a 3D fluid. I am aware that some may say that it is people like me who are wasting their time and efforts. That is perfectly fine with me. I have been always preferring to let the results obtained do the talking and the convincing.

One last note to avoid any misunderstanding. Every avenue should be explored, but it should be done in a critical manner. Instead of trying to collect arguments in favour of the 3D aether (in this example) one must try to find COUNTER arguments first.