A research collaboration between Queen Mary University of London, the University of Cambridge and the Institute of High Pressure Physics in Troitsk discovered the fastest possible speed of sound.
The result – about 36 kilometers per second – is twice the speed of sound in diamond, the strongest known substance in the world.
Waves, like sound or light waves, are disturbances that transfer energy from one place to another. Sound waves can travel through different media, such as air or water, and move at different speeds depending on what they are traveling through. For example, they move through solids much faster than liquids or gases, which is why you would be able to hear a train approaching more quickly if you were to hear the sound propagating in a railroad track rather than in the air.
Einstein’s theory of special relativity defines the maximum speed at which a wave can travel, which is the speed of light, equal to about 300,000 kilometers per second. However, it was not yet known whether sound waves also have a maximum velocity when traveling through solid or liquid materials.
The study published in the journal Science advances, Shows that prediction of the upper limit of the velocity of sound depends on two basic dimensionless constants: the microstructure constant and the proton-to-electron mass ratio.
These two numbers are already known to play an important role in understanding our universe. Their finely tuned values control 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-supportive molecular structures can appear. However, the new findings indicate that these two fundamental constants could also influence other scientific fields, such as materials science and condensed matter physics, by setting limits to certain properties of materials such as the speed of sound.
Scientists have tested their theoretical predictions on a wide range of materials and addressed one specific prediction of their theory that the speed of sound should decrease with the mass of sound. corn. This prediction indicates that the sound is the fastest in solid atomic hydrogen. However, hydrogen is an atomic solid at a very high pressure just above 1 million atm pressure, and a pressure comparable to that in the core of gas giants such as Jupiter. At these pressures, hydrogen becomes a superb metallic solid that is electrically conductive just as much as copper and is expected to be a superconductor at room temperature. Therefore, the researchers conducted the latest quantum mechanics calculations to test this prediction and found that the speed of sound in solid atomic hydrogen is close to the theoretical base limit.
Professor Chris Pickard, Professor of Materials Science at Cambridge University, said: “Sound waves in solid materials are indeed of great importance in many scientific fields. For example, seismologists use sound waves produced by earthquakes deep in the Earth’s interior to understand the nature and properties of seismic events. “Earth formation. It is also of interest to material scientists because sound waves are associated with important elastic properties, including the ability to resist stress.”
Professor Kostia Trachenko, Professor of Physics at Queen Mary, added: “We believe that the results of this study could have additional scientific applications by helping us find and understand the limits of various properties such as viscosity and thermal conductivity related to superconductivity at high temperatures, quark glon. plasma And even Black hole Physics. “
Reference: “The Speed of Sound is an Fundamental Physical Constants” Posted by K. Trachenko, B. Monserrat, CJ Pickard, and VV Brazhkin, 8 October 2020, Available here. Science advances.
DOI: 10.1126 / sciadv.abc8662
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