Sound can be transmitted in a vacuum
In outer space, according to physics textbooks, no one will hear you. Only spaceships from Hollywood movies, like “Aliens”, are heard. However, in some special cases, sound can move between objects in a vacuum from object to object, reports NewScientist.Com.
As we know from the school physics course: sound waves propagate in solid, gaseous and liquid media, through vibrations of the particles of the medium. It goes without saying that they will not be able to pass through empty space, where there are no particles (atoms, molecules) capable of vibrating.
Finnish scientists Mika Prunnila and Johanna Meltaus, from the Espoo research center, suggest so far only a theoretical diagram showing how sound can jump through the vacuum separating two objects made of piezoelectric crystals. These crystals generate an electric field, they are compressed or stretched by the action of sound waves or other forces, and as a result, the created electric field changes.
When a sound wave reaches the edge of one crystal, the electric field associated with it and passing through the vacuum can change and deform the other crystal, generating sound waves in the latter. “It’s as if the sound waves didn’t even know about the vacuum – they just passed directly,” says Prunnila.
The researchers say the gap should not be particularly small, and the efficiency of sound transfer should vary depending on the frequency of the sound wave and the angle at which the wave “enters” the first crystal. Some combinations of waves almost do not lose energy when jumping over the vacuum gap.
The team hopes to show the effect experimentally soon. “This kind of work is interesting from a fundamental point of view,” says Chen Gang of the Massachusetts Institute of Technology.