Scientists have determined the maximum possible speed of sound
An international group of scientists has set an upper limit for the speed of sound, which is around 36 kilometers per second. So far, the highest speed of sound has been measured in a diamond and was only about half of the stated maximum.
Sound waves can penetrate various media such as air or water. Depending on what they are crossing, they move at different speeds. For example, they move much faster through solids than through liquids or gases, so an oncoming train can be heard sooner if you listen to the sound traveling along the route rather than in the air.
Albert Einstein's special theory of relativity sets an absolute limit to the speed at which a wave can propagate, namely the speed of light, which is around 300.000 km per second. So far, however, it is not known whether sound waves also have an upper speed limit when crossing solids or liquids. Until now. Scientists at Queen Mary University of London, Cambridge University, and the Institute of High Pressure Physics in Troiksk, Russia, have found that the speed of sound depends on two dimensionless fundamental constants: the subtle structural constant and the ratio of proton mass to electron. The results of their work are in the magazine "Science Advances"has been published. (Image source: Pixelbay)
speed of sound
Kostya Trachenko from Queen Mary University in London and his colleagues began their research with two well-known physical constants: the ratio of proton mass to electron mass and the subtle structural constant that characterizes the force of interactions between charged particles. According to Trachenko, we have a pretty good idea of these values. If they had been changed at least a little, the universe wouldn't look the way it does. - If we change these constants by a few percent, the proton may no longer be stable, and even the processes in stars could stop, which would lead to the synthesis of heavy elements, so that there would be no more carbon and no more life, "says Trachenko .
These two constants play an important role in understanding our universe. Their finely tuned values regulate nuclear reactions like proton decay and nuclear fusion in stars, and the balance between them ensures the existence of an ecosphere, that is, a place around the stars where the planets have the right conditions to sustain life. New discoveries however, suggest that these two fundamental constants can influence other areas of science, such as materials science and condensed matter physics, by setting specific limits on material properties, such as the speed of sound.
These constants rule the cosmos, and the speed of sound is limited to them. The speed of light determines the ultimate speed limit in the universe. A subtle structural constant determines the force with which electrically charged particles interact with one another. In combination with another constant - the ratio of proton and electron masses - these numbers result in the limit of the speed of sound.
Maximum speed of sound
Sound is a wave that propagates, causing neighboring particles to interact, so their speed depends on the density of the material and the way the atoms in it are connected. Trachenko and his colleagues have made use of this fact and, together with the ratio of the mass of the proton to the electron and the constant of the subtle structure, calculated the maximum speed with which a sound could theoretically move in any liquid or solid: about 36 kilometers per second. - It was widely believed that the sound in a diamond reached the highest speed because it was the hardest material, but we didn't know if there were theoretically fundamental restrictions on the speed at which a sound can move, "says Trachenko .