Fundamental constants set upper limit for the speed of sound
To Kostya Trachenko of Queen Mary University of London, Bartomeu Monserrat, Chris Pickard of the University of Cambridge and Vadim Brazhkin of the Russian Academy of Sciences for calculations showing that 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. The team’s theoretical prediction is backed up by experimental data of the speed of sound in a range of solid materials and a calculation of the speed of sound in metallic hydrogen – a material that is yet to be created in the lab but should have the fastest speed of sound. The research provides insight into how fundamental constants impose bounds on physical properties.
more details at https://physicsworld.com/a/physics-world-announces-its-breakthrough-of-the-year-finalists-for-2020/