Fundamental constants set upper limit for the speed of sound – physicsworld.com

Upper limit: a US Navy F/A-18 travelling near the speed of sound in air. The white halo comprises water droplets that have condensed from the air because of the sudden drop in pressure behind the shock cone around the aircraft . (Courtesy: John Gay/US Navy)
The upper limit on the speed of sound in solids and liquids depends on just two dimensionless quantities the fine structure constant and the proton-to-electron mass ratio. That is the surprising conclusion of physicists in the UK and Russia,…

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