Paradoxes of the theory of relativity
Quantum Paradox
Quantum theory and relativity theory emerged at the beginning of the twentieth century to give answers to unexplained issues in physics: the blackbody spectrum, the structure of atoms and nuclei, the electrodynamics of moving bodies. Many years later, information theory was developed by Claude Shannon (1948) for analyzing the efficiency of communication methods. How do these seemingly disparate disciplines relate to each other? In this review, we shall show that they are inseparably linked.
Common presentations of relativity theory employ fictitious observers who send and receive signals. These ''observers'' should not be thought of as human beings, but rather as ordinary physical emitters and detectors. Their role is to label and locate events in spacetime.
The speed of transmission of these signals is bounded by c-the velocity of light-because information needs a material carrier, and the latter must obey the laws of physics. Information is physical (Landauer, 1991). However, the mere existence of an upper bound on the speed of propagation of physical effects does not do justice to the fundamentally new concepts that were introduced by Albert Einstein (one could as well imagine communications limited by the speed of sound, or that of the postal service).
Einstein showed that simultaneity had no absolute meaning, and that distant events might have different time orderings when referred to observers in relative motion. Relativistic kinematics is all about information transfer between observers in relative motion.
Classical information theory involves concepts such as the rates of emission and detection of signals, and the noise power spectrum. These variables have welldefined relativistic transformation properties, independent of the actual physical implementation of the communication system. A detailed analysis by Jarett and Cover (1981) showed that the transmission rates for observers with relative velocity v were altered by a factor (c1v)/(c2v), namely, the square of the familiar Doppler factor for frequencies of periodic phenomena.
We shall later derive the same factor from classical electromagnetic theory . Physics has a remarkably rigid theoretical structure: you cannot alter any part of it without having to change everything .
