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Description
In sonic models of relativity, observers outside the sonic medium perceive the violation of ordinary Lorentz symmetry, while agents measuring distances and durations using sound pulses within the medium don't. Surprisingly, these "sonic observers" will interpret the physics of ordinary particles (like photons) as violating their own sonic Lorentz symmetries. In previous work, we argued that scattering experiments from ordinary particles could allow sonic observers to determine (1) the existence of an ether universe and (2) the rest frame of the ether (the sonic medium). However, we contend that this isn't what these observers would reasonably conclude. Instead, they'd likely maintain their belief in the ether-free nature of sound and interpret the velocity-dependent scattering effects as reflecting the ether-bound nature of photons. While this interpretation may seem absurd from an external perspective, it would be natural to them. Since photons are supersonic, to these observers, they would appear as tachyons confined to a novel type of material, which we call a "tachyonic medium." Sonic observers would conclude that these tachyons don't create causal paradoxes due to their confinement within the medium, while external observers would argue that causal paradoxes are inherently impossible since everything occurs within a laboratory setting. We extend this reasoning to various fields with different Lorentz-invariant speeds and demonstrate that all observers have the freedom to choose which speed is invariant. This choice is influenced by the tools and methods used for measurements and a desire for simplicity in describing physical laws. (This freedom exists within ordinary relativity but is rarely discussed.) This conceptual framework suggests that the hypothetical detection of actual (superluminal) tachyons might not be as problematic as commonly believed. Specifically, if such tachyons were measured to travel as if confined to a tachyonic medium, Lorentz symmetry could be rationally maintained, and no causal paradoxes would necessarily arise. Sundance O. Bilson-Thompson, Scott L. Todd, James Read, Valentina Baccetti, and Nicolas C. Menicucci, "Tachyonic media in analog models of special relativity," Phys. Rev. D 108, 124020 (2023). DOI: 10.1103/PhysRevD.108.124020
