Quantum-Gravity Phenomenology and the DSR Ether Theories
Guided primarily by versions of a theoretical framework called Doubly Special Relativity, or DSR, that are supposed to entail speeds of light that vary with energy while preserving the relativity of inertial frames, quantum-gravity phenomenologists have recently been seeking clues to quantum gravity, in hoped-for differing times of arrival, for light of differing energies, from cosmologically distant sources. However, it has long been known that signals, of arbitrarily high speed in opposing directions, could be used to observe the translational state of (absolute) rest, as could signals of a fixed speed different from c. Consequently, the above versions of DSR are nonviable.
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