The acoustic physics of plasma are not well understood, so what the speed of sound would be then is anyone’s guess. It would, though, need to be at well over 1m degrees for this to happen, and at that temperature it would have turned to plasma. In gases, the speed of sound increases with temperature, so the newly described speed limit might be exceeded were a gas hot enough. This last is a parameter from quantum theory, the branch of physics which describes the universe on its smallest scales.ĭr Trachenko’s insights do not apply to uncondensed matter-namely gases and the state of matter called plasma, in which electrons break free from their parent atoms. The others are the mass of an electron, the mass of a proton and something called the fine-structure constant. His formula depends only on four fundamental constants of nature. Part of what makes Dr Trachenko’s work so surprising is the way he arrived at this figure. That testable prediction of his theory is twice the current measured record for condensed-matter sound waves, which is held by diamond-ie, crystallised carbon. But Dr Trachenko’s analysis predicts that if and when this is done, the result will be about 36,000 metres per second. Unfortunately hydrogen, which generally exists as a gas, is notoriously difficult to squeeze into a solid form, so measuring the speed of sound within its solid phase is tricky. Sound’s highest speed in such matter, they therefore predict, will be through a solid made of the lightest atoms: hydrogen. The lighter the particle doing the vibrating, the faster it transmits sound. Allowing for differences in properties such as density and interatomic bond strength, Dr Trachenko and his colleagues calculated that the speed of sound in condensed matter obeys a simple trend. When one moves, its neighbours follow suit, and a wave of sound is thus transmitted. In solids and liquids-known collectively to physicists as the condensed phases of matter-molecules are bound to one another tightly. Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Sound travels by making things vibrate.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.
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