The Speed of Light: Constant and Non-Constant
Year: 2013 Pages: 6
Keywords: Light, Simultaneity, Laser, Radiation Continuum
Two very interesting postulates by Calkins and Renshaw can be combined into a reasonable description of the ?observed? constancy of the speed of light from a stationary source in any particular ?medium,? while allowing this speed to vary within the same medium with a moving source. If light travels at a constant speed in a given medium when emitted from a stationary source, and if it is analogous to sound or water waves, then it would not exhibit different speeds when emitted from a moving source within the same medium, only the traditional Doppler Shift, i.e., change in frequency and wavelength, but not speed. Light behaves ?Galileanly? by acquiring the velocity vector of a moving source, allowing for speeds different from c. Renshaw supports this by assuming the source motion ?moves? the observer to a different point on the ?elastic,? or light beam where, while a constant speed is still observed, the ?true? speed differs from c. In air or water, or any other ?material? medium, Calkins acknowledges the role of the medium itself to providing ?resistance? to the wave in addition to that inherently provided by the compression of any electromagnetic fields already present due to the atoms comprising the medium. Thus, a moving source in such a medium has its speed limited by the resistance from that medium itself. However, if the material medium itself were also moving in its entirety, say along with the source, then the net result would be a wave propagating at the constant speed in the medium itself PLUS that speed of the moving medium (summed vectorially), at least to an ?outside? observer (i.e., one not moving with the moving medium). Light has no ?material? medium in the sense of that for sound or water waves ? only the electromagnetic field itself. Therefore, when the source (of light) moves, the electromagnetic field (the ?medium?) moves along with it, since the medium is generated from the source. Could not this be the analogy that allows for ?Galilean? addition of the c and v vectors for a moving source of light? And from Renshaw\'s Radiation Continuum Model approach, could not this speed of light different from c correspond to being able to observe the ?true? speed from a different ?point? along the ?elastic? beam?
 See also ?Questioning the Cosmological Doppler Red-Shift,? by Gallucci.