ABSTRACT
The Global Navigational Satellite Systems (GNSS) based on a network of satellites around the Earth, like the GPS, rely on precision atomic clocks and radio signals to locate a ‘receiver’ in space, typically at or near the Earth’s surface. GLONASS (Russia), Galileo (Europe), and BeiDou (China) are other global systems. There are also regional navigational systems, such as the IRNSS/NavIC (India) and the QZSS (Japan). These high-precision navigational systems with good ‘civilian access’ are technologically and socially transformational. The basic idea that relies on the light hypothesis is simple. If the relative velocity of light does not depend on the velocity of either the source or the observer, the observer is equivalent to a stationary location, with the rest of the world moving relatively. Then, the duration to propagate from the source to the observer, when multiplied by the constant c, is equal to the distance between them, irrespective of any motion of the observer. Thus, GPS-like systems rely on the hypothetical equivalence of space and time (Ashby, 2002, 2003).
