A British-led international team has found the maximum speed of sound, about 100 times that in air
He is about to end up run over, his mother saves himThe sound can travel a maximum of 36 kilometers in one second: an international team led by English has found the maximum speed of sound, about 100 times that in the air. The discovery opens important doors on seismology and materials sciences.
The speed of sound in air is about 340 meters / s (numbers that vary with temperature), which means about 0.3 kilometers / s. However, this value changes significantly with the medium in which the sound propagates because, unlike light, sound is a mechanical wave, which needs a "support" to travel.
Just as it is different to travel by bike or by plane, this wave also moves more or less quickly according to "who brings it". However, today we know that its speed cannot exceed 36 km / s, about 100 times that in the air.
In general, sound propagates better in solids than in liquids or gases, which is why we hear an approaching train much earlier if we bring our ears closer to the tracks instead of leaving them in contact with the air.
The study that found this value, now called the upper limit of the speed of sound, was conducted on a theoretical level and demonstrated how this prediction depends on two fundamental factors: the fine structure constant and the proton-electron mass ratio.
These two constants were already known, among other things, to govern nuclear reactions such as proton decay and nuclear synthesis in stars, as well as to define the narrow "habitable zone" where stars and planets can form and the molecular structures that support them. life can emerge.
Scientists, however, did not stop to make theoretical predictions based on calculations and calculations, but also tested their hypotheses on a wide range of materials, showing that the value decreases with the mass of the atom, and that therefore the sound is faster in solid atomic hydrogen, since hydrogen is the chemical element with the smallest mass.
This new 'mathematically perfect' material is capable of canceling out any sound
However in nature hydrogen is notoriously a gas (molecule formed by two equal atoms), and becomes an atomic solid only at very high pressure, above 1 million atmospheres, comparable to that in the nucleus of gas giants such as Jupiter. At those pressures the element conducts electricity just like copper and is expected to be a superconductor at room temperature.
All calculated and all verified: the researchers have in fact discovered through cutting-edge quantum mechanical calculations that the speed of sound in solid atomic hydrogen it is close to the theoretical fundamental limit.
The scope of the discovery is first and foremost scientific: until now it was known only what was the absolute speed limit at which a wave can travel, that of light, (about 300.000 km / s, as established by Einstein's theory of relativity) . But light is an electromagnetic wave and the value is that in the void. For the first time now it turns out that even through a medium there is an upper limit that a wave cannot exceed.
But it doesn't stop there.
"Sound waves in solids are already extremely important in many scientific fields - explains Chris Pickard, co-author of the study - For example, seismologists use sound waves triggered by deep earthquakes inside the Earth to understand the nature of seismic events and the properties of the composition of our planet. They are also of interest to materials scientists because sound waves are related to important elastic properties, including the ability to resist stress ”.
The step taken could therefore be a leap in many technological fields, some of which are particularly important to us.
The research was published in Science Advances.
Sources of reference: Queen Mary University of London / Science Advances
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