When we talk on speed of sound, we usually mean how fast’ it moves through air. But it can travel much faster through other media, and now scientists at the University of Cambridge & Queen Mary University of London have identified-absolute top speed of sound.
The team found that at its fastest, sound can travel at 36 km (22.4 mi) per sec. That’s almost 100 times faster than its average speed through air, which is 343 m (1,125 ft) per sec, & 3 times faster than its previously-measured top speed of 12 km (7.5 mi) per sec, through diamond.
So what medium lets sound travel at such a high speed? consistent with the new study, it’s solid atomic hydrogen. This form of element only occurs under immense pressure, like that found at the core of gas planet planets like Jupiter. Under those conditions, hydrogen is compressed into a metallic solid which can easily conduct electricity – and, it turns-out, sound.
The researchers came to a conclusion by studying 2 fundamental constants – the fine structure constant and therefore the proton-to-electron mass ratio. These numbers play huge roles in a sort of scientific fields, including in this case, material properties.
One prediction made by a theory is that the speed of sound should decrease with the mass of the atom, so by extension sound should travel fastest in solid atomic hydrogen. The team used quantum mechanical calculations to check just how fast it might move through material, and found that the speed is too close of the theoretical fundamental limit.
Besides being fascinating, this type of study won’t have all that much impact on our everyday lives, but the team says that improving our understanding of those fundamental constants & limits can improve our models for a range of sciences.
“We believe the findings of this study could have further scientific applications by helping us to seek out & understand limits of various properties like viscosity & thermal conductivity relevant for high-temperature superconductivity, quark-gluon plasma and even black hole physics,” says Kostya Trachenko, lead author of the study.