2023-08-17 14:01:04
The tagline for the 1979 classic horror film Alien read, “In Space, No One Can Hear You Scream.” This may be primarily intended as a snappy saying, but it also reveals a widespread assumption: The fact that in space there is no noise due to the vacuum. However, a new study shows that this is entirely possible.
Space: Piezoelectricity can make noise possible
It has long been assumed that sound cannot propagate in a vacuum and therefore also in space. After all, there is actually nothing in the vastness of the universe that could favor this. But two scientists from the University of Jyväskylä in Finland now want to have provided proof that this would theoretically be possible in a perfect vacuum.
It should be mentioned that a so-called high vacuum with low particle density prevails in space. So it is not completely empty, since gases, cosmic dust, elementary particles, electric and magnetic fields, gravitational fields and electromagnetic waves exist, among other things. For your Study However, the researchers wanted to find out which conditions must prevail in order to enable the transmission of sounds.
At the heart of their investigation are piezoelectric materials. That is, they can convert mechanical energy into electrical and vice versa. If you now place two piezoelectric objects next to each other and give them a corresponding stimulus, this can be passed on through the properties of the objects. The same can be said for noise as well.
Also exciting: Using special methods, researchers have published sounds from a black hole. However, the result was not without criticism of NASA.
Sounds “jump” from object to object in the vacuum
For their experimental setup, Geng and Maasilta chose two piezoelectric crystals made of zinc oxide. The distance between them – a vacuum – could not be wider than the wavelength of an initial sound. This is normally caused by vibrations, which in turn cause atoms and molecules to vibrate in the corresponding medium. This process continues until the vibrations are registered by membranes in our ears.
In the experiment, there was an exit sound that exerted mechanical pressure on one of the crystals through its vibrations. This converted this stimulus into an electric field. The second crystal in turn registers this and converts this field back into mechanical energy. As a result, the sound wave also traveled further in the vacuum between the crystals.
It goes on to say that the experimental setup works with different frequencies and thus also with ultrasound, for example – provided the vacuum gap is scaled to the size of the acoustic wavelength. Whether and to what extent this can ever be applied to real space is questionable. Instead, the findings on the piezoelectric processes could be useful in other research fields.
Quelle: „Complete tunneling of acoustic waves between piezoelectric crystals“ (Communication Physics 2023)
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