Scientists Find the Upper Limit of the Speed of Sound


Scientists from three different institutions set out to discover the fastest speed that the speed of sound could reach. Scientists have conducted tests predicting that sound will travel fastest in atomic solid hydrogen.

The speed of sound is taken as 343 m / s (approximately 1,235.5 km / h) at sea level, air and 20 degrees temperature as standard. Of course, when conditions change, the speed of sound also changes. So what is the maximum speed that sound can reach? Scientists gave the answer to this recently.

Researchers from Queen Mary London University, University of Cambridge, and the Institute for High Pressure Physics came together to find the maximum speed of sound. Scientists have made sound moving in diamond, the hardest material in the world, at twice the speed. The sound traveled at a speed of about 36 km / sec.

How was the study done?

Sound waves can move in various environments such as air and water, and the speed of movement of the waves also varies according to this environment. For example, because the sound travels faster on the solids, you can hear the unheard sound of a train in the air, when you rest your head on the rails.

Einstein’s theory of relativity holds the maximum speed a wave can travel equal to the speed of light. However, until now, it was not known whether sound waves had an upper velocity limit when passing through solids or liquids. Estimating the upper limit of the speed of sound, according to new research by scientists, depended on two dimensionless fundamental constants: the fine structure constant and the proton-electron mass ratio.

These two constants already play an important role in our understanding of the universe. The precise values ​​of constants govern nuclear reactions such as proton decay and nuclear synthesis in stars, and the balance between the two numbers provides a narrow ‘habitable zone’ where stars and planets can form and life-supporting molecular structures can emerge.

Scientists’ new discovery suggests that these two fundamental constants can also affect other fields of science, such as materials science and condensed matter physics, by placing limits on certain specific material properties, such as the speed of sound. Scientists have tried this theory in a variety of materials and got the prediction of their theory that the speed of sound should decrease with the mass of the atom.

This prediction of the scientists meant that sound traveled fastest in solid atomic hydrogen. But hydrogen was atomically solid only at pressures like the pressure in the core of gas giants like Jupiter. So scientists performed the most recent quantum mechanical calculations to carry out their work and found that the speed of sound in solid hydrogen was close to the theoretical fundamental limit.


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