Physics

Maximum speed of sound calculated at 100 times faster than through air

Maximum speed of sound calcula...
A new study has calculated the top speed of sound, which might occur in an exotic form of hydrogen
A new study has calculated the top speed of sound, which might occur in an exotic form of hydrogen
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A new study has calculated the top speed of sound, which might occur in an exotic form of hydrogen
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A new study has calculated the top speed of sound, which might occur in an exotic form of hydrogen

When we talk about the speed of sound, we usually mean how fast it moves through air. But it can travel much faster through other media, and now scientists at the University of Cambridge and Queen Mary University of London have identified the absolute top speed of sound.

The team found that at its fastest, sound can travel at 36 km (22.4 mi) per second. That’s more than 100 times faster than its average speed through air, which is 343 m (1,125 ft) per second, and three times faster than its previously-measured top speed of 12 km (7.5 mi) per second, through diamond.

So what medium lets sound travel at such a high speed? According to the new study, it’s solid atomic hydrogen. This form of the element only occurs under immense pressure, such as that found at the core of gas giant planets like Jupiter. Under those conditions, hydrogen is compressed into a metallic solid that can easily conduct electricity – and, it turns out, sound.

The researchers came to this conclusion by studying two fundamental constants – the fine structure constant and the proton-to-electron mass ratio. These numbers play huge roles in a variety of scientific fields, including in this case, material properties.

One prediction made by the theory is that the speed of sound should decrease with the mass of the atom, so by extension sound should travel fastest in solid atomic hydrogen. The team used quantum mechanical calculations to test just how fast it would move through the material, and found that the speed is close to the theoretical fundamental limit.

Besides being fascinating, this kind of study might not have all that much impact on our everyday lives, but the team says that improving our understanding of these fundamental constants and limits can improve our models for a range of sciences.

“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,” says Kostya Trachenko, lead author of the study.

The research was published in the journal Science Advances.

Source: Queen Mary University of London

8 comments
buzzclick
So the fastest sound can travel is at 36km/sec through solid hydrogen, but what about amplitude? Does a stronger signal travel faster than a weaker one? Also, does sound not travel at all in a vacuum? If you were able to stay alive floating in space and witnessed a massive collision of two interplanetary bodies, would you hear absolutely nothing?
schmoe90
yes, buzzclick, in space nobody can hear you scream - sound needs to travel by vibration (measured in Hz), so in a vacuum, it won't travel. A "stronger" signal travels at the same speed, same as light.
ColinChambers
Motion =energy =force =pressure =information =instinct = attraction =motion... The fundamental principle of conservation law of the universe to create order from disorder. Compressed hydrogen is a structure of material with properties -atoms - laws of nature, this study is interesting but it has to includesThermal energy, compounds structures property all have changes close to Kelvin zero. Thermal energy will no exist.
Jacktar
Nibblonian
@buzzclick: 1) As long as the medium is consistent, the speed of sound will be consistent, regardless of amplitude. 2) Correct, sound does not travel in a vacuum -- which makes all of those sci-fi scenes of spacecraft screaming through space a bit absurd. (That said, if you were inside a space suit or space craft filled with air and an energy wave struck, the mechanical barrier could act as a transducer and convert the energy into sound--pretty similar to how a speaker works).
Karmudjun
So our Atlas Rocket only attained one-third of the speed of sound (through solid hydrogen) during the moon shots. Hard to fathom - but also hard to consider a use for such information. We know aural sound is not propagated in a vacuum from H.S. bell jar demonstrations using partial vacuums, so there is an understanding that we do not hear sounds in a vacuum. But we can detect the 'sound of the Big Bang' with radio telescopes, but that is not an aural wave.
WB
sound does not travel in vacuum so in space no one can hear you scream... or you won't hear the supernova going off right next to you - but you might feel it :-)
1stClassOPP
So, how do radio waves travel through space?, do the not set off some type of vibration too?
Arabinda Pradhan
And it is a good news for particle physics in future. Sound travels through space wheather one hears or not. So wave is wave wheather it is aural or not. Better to try thinking how physicists concentrate to look for sound whatever David Bohm remarks as turn upside down.