Sound travels 100 times faster through solid metallic hydrogen than it does through air

Scientists calculate the 'speed of sound limit'.

Engadget JP (Translation)
Engadget JP (Translation) , @Engadget_MT
2020年10月13日, 午後 06:03 in egmt
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This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl.


When we talk about the speed of sound, we think of it as the speed at which it travels through the air, that is, about 340 meters per second (at 15 degrees Celsius, the speed increases or decreases by 0.6 meters per second for every 1 degree Celsius). However, the speed of sound varies depending on the medium, for example, the speed of sound in helium gas at 15°C is 997m/second.

Scientists at the University of Cambridge and Queen Mary University of London looked at the materials that allow sound to travel the fastest and found that it can reach speeds of up to 36 kilometers per second. This means it travels 100 times faster than the speed in the air.

So what is the substance that can transmit sound so fast is of interest, the researchers explain that it is hydrogen that has been condensed by very high pressure into a metallic form. The centers of giant gas planets like Jupiter, for example, are under very high pressure, and it is speculated that in such places, hydrogen is compressed into a solid with conductive metallic properties.

The scientists explain that they arrived at their conclusions by using two assets: the fine structure constant, which characterizes the strength of interactions between charged particles, and the ratio of the mass of the proton to the mass of the electron. Kostya Trachenko of Queen Mary University of London says, "The common wisdom was that diamond has the highest speed of sound because it is the hardest material, but we didn’t know whether there was a theoretical fundamental limit to it."

This theory predicts that the speed of sound propagating through the material decreases as the atomic mass increases, and conversely, the sound would travel the fastest in solid metallic hydrogen. The researchers used computers to estimate how fast sound could travel through matter and found that the speed was close to the theoretical fundamental limit.

This kind of research may not have any impact on our lives, but it is appealing as a purely intellectual pursuit. On the other hand, from a researcher's point of view, a better understanding of these fundamental constants and theoretical limitations can improve various scientific models.

Trachenko says, "We believe the findings of this study could have further scientific applications by helping us to find and understand limits of different properties such as viscosity and thermal conductivity relevant for high-temperature superconductivity, quark-gluon plasma and even black hole physics.”

However, Graeme Ackland of the University of Edinburgh is more cautious and expresses his own belief that "you can use these fundamental constants to get something with units of velocity, but I can’t quite see a good fundamental reason for why it is a bound. I’m not completely convinced.” He says that more work is necessary to find exactly how it applies to sound moving through heavier elements.

Source: Science Advances

Via: New Scientists, New Atlas


This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl. The Japanese edition of Engadget does not guarantee the accuracy or reliability of this article.


 

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関連キーワード: egmt, physics, Sound, Speed, speed of sound, Queen Mary University of London, University of Cambridge, University of Edinburgh, the ratio of proton mass to electron mass, the fine structure constant, science, news, gear, tomorrow
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