Friday, October 1, 2010

Sound can leap across a vacuum after all - New Scientist - New Scientist

Sound can leap across a vacuum after all: Now a theoretical analysis by Mika Prunnila and Johanna Meltaus, both of the VTT Technical Research Centre of Finland in Espoo, suggests that sound may be able to leap across a vacuum separating two objects made of piezoelectric crystals. These crystals generate an electric field when squeezed or stretched by sound waves or other forces, and deform in an electric field.

When a sound wave reaches the edge of one crystal, the electric field associated with it can stretch across the gap and deform the crystal on the other side, creating sound waves in that second crystal (Physical Review Letters, vol 105, p 125501). "It is as if the sound waves don't even recognise the vacuum - they just go through," says Prunnila.

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