A formulation of the one-way speed of light in three-dimensional Euclidean space is derived by a constructive approach. This formulation is consistent with the result of the Michelson-Morley experiment in that the harmonic mean of the outward and return speeds is equal to c, the standard value for the speed of electromagnetic radiation in vacuum. It is also shown that a shift in synchronization, proportional to the distance along the line of motion, renders this speed a constant along all directions.Comment: Nineteen Pages, two table

In the rod and hole paradox as described by Rindler (1961 Am. J. Phys. 29 365-6), a rigid rod moves at high speed over a table towards a hole of the same size. Observations from the inertial frames of the rod and slot are widely different. Rindler explains these differences by the concept of differing perceptions in rigidity. Grøn and Johannesen (1993 Eur. J. Phys. 14 97-100) confirmed this aspect by computer simulation where the shapes of the rods are different as observed from the co-moving frames of the rod and slot. Lintel and Gruber (2005 Eur. J. Phys. 26 19-23) presented an approach based on retardation due to speed of stress propagation. In this paper we consider the situation when two parallel rods collide while approaching each other along a line at an inclination with their axis. The collisions of the top and bottom ends are reversed in time order as observed from the two co-moving frames. This result is explained by the concept of 'extended present' derived from the principle of relativity of simultaneity.

In the conventional rod and slot paradox, the rod, if it falls, was expected to fall into the slot due to gravity. Many thought experiments have been conducted where the presence of gravity is eliminated with the rod and slot approaching each other along a line joining their centers, whereby the considerations come strictly under Special Relativity. In these experiments the line of motion is not parallel to either the axis of the rod or the slot. In this paper we consider in detail the two cases when the rod does fall into the slot and when the rod does not fall into the slot, each from the perspective of the co-moving frames of the rod and the slot. We show that whether the rod falls into the slot as determined by Galilean kinematics is also valid under relativistic kinematics; this determination does not depend upon the magnitude of the velocity, but only on the proper lengths and the proper angles of the rod and slot with the line of motion. Our conclusion emphasizes the fact that the passing (or crashing) of the rod as a wholesome event is unaffected by relativistic kinematics. We also provide a simple formula to determine whether or not the rod passes through the slot.

Sometimes it becomes a matter of natural choice for an observer (A) that he prefers a coordinate system of two-dimensional spatial x-y coordinates from which he observes another observer (B) who is moving at a uniform speed along a line of motion, which is not collinear with A's chosen x or y axis. It becomes necessary in such cases to develop Lorentz transformations where the line of motion is not aligned with either the x or the yaxis. In this paper we develop these transformations and show that under such transformations, two orthogonal systems (in their respective frames) appear nonorthogonal to each other. We also illustrate the usefulness of the transformation by applying it to three problems including the rod-slot problem. The derivation has been done before using vector algebra. Such derivations assume that the axes of K and K' are parallel. Our method uses matrix algebra and shows that the axes of K and K' do not remain parallel, and in fact K and K' which are properly orthogonal are observed to be non-orthogonal by K' and K respectively.

This contribution adds to the points on the ‘indeterminacy of special relativity’ made by de Abreu and Guerra. We show that the Lorentz transformation can be composed by the physical observations made in a frame K of events in a frame K′, namely (i) objects in K′ are moving at a speed v relative to K, (ii) distances and time intervals measured by K′ are at variance with those measured by K and (iii) the concept of simultaneity is different in K′ compared to K. The order in which the composition is executed determines the nature of the middle aspect (ii). This essential uncertainty of the theory can be resolved only by a universal synchronicity as discussed in [1] based on the unique frame in which the one-way speed of light is constant in all directions.