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# Science finds the upper limit of the speed of sound: 36 km / s

Science has added a new constant: what is the maximum speed of sound in liquid / solid materials?

Whether electromagnetic or gravitational, the speed limit of any kind of wave in a vacuum has remained the same, since the day Albert Einstein successfully developed the theory of relativity in 1905. Science has just calculated the maximum speed of sound when traveling in solid or liquid objects: we have the number 36 km / s, which is about 8,000 times slower than the speed of light in a vacuum.

To derive this result, physics professor Kostya Trachennko and colleagues used two famous constants in physics: the ratio of the mass of the proton to the mass of the electron, in addition to the fine structure constant. Fact shows the magnitude of interactions between charged elementary particles.

Trachenko commented that science has a pretty solid foundation to be confident in the accuracy of the constants mentioned above, because if they only move a little, this Universe will be much different from the present. “If the constant was only a few percent deviation, the proton would lose its stability, and perhaps heavy element synthesis going on in a star would be gone, so we wouldn’t have carbon, we wouldn’t have life.“, Said Professor Trachenko.

Sound is a wave that is transmitted in matter by interacting with particles, the speed of sound depends on the mass density (density) of matter – that is, the atoms that make matter are close together, interact with each other how. An atom has a maximum speed, so the speed of sound is limited by this quantity.

Trachenko et al. Used this fact and the proton-electron mass ratio, the subtle structural constant to calculate the maximum speed of sound as it travels through a liquid or solid: in theory, the The bar can move at a maximum speed of 36 km / s.

We still know diamonds will give the maximum speed of sound transmission, because they are the hardest material, but we don’t know if there is a theoretical speed limit.“, Said Professor Trachenko. The team calculated that this maximum speed is almost twice the speed at which sound travels in diamonds.

The speed of sound also depends on the mass of the atom in the matter, so the researchers predicted that metallic solid hydrogen – a material that exists theoretically, could be in the cores of the onions. giant crystal – is the fastest transmission material for sound. According to calculations, the sound traveling in metal hydrogen will have a speed close to the upper limit. Of the 133 materials tested, neither was able to transmit sound faster than the 36 km / s mark.

However, Professor Graeme Ackland of the University of Edinburgh thinks Trachenko et al’s calculations have not yet calculated the maximum speed of sound. Ackland contradicted:You can use the fundamental constant to get some element of the velocity unit, but there’s no reason why a speed limit exists. I don’t believe it yet“.

Professor Ackland suggested that more testing is needed to observe the speed at which sound moves in heavier elements.

Consult New Scientist

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