Scientists have proven that sound can actually travel across the ostensibly empty space of a vacuum in a ground-breaking study.
Researchers have discovered a method to transfer sound in
environments that replicate the vacuum of space, defying the widely held
assumption that "no one can hear you scream"—a view that was further
cemented by the classic tagline of the 1979 science fiction film
"Alien."
The Science Behind the Sound
Conventionally, sound waves move through a medium's
particles—such as air or water—by vibrating. It was previously believed that
this transmission was not conceivable in the immensity of space, which is primarily
a vacuum devoid of particles. But in this ground-breaking experiment,
researchers were able to "tunnel" sound waves between two crystals of
zinc oxide across a vacuum. They did this by translating the waves of vibration
into ripples inside a common electric field between the two crystals.
The Role of Zinc Oxide Crystals
As piezoelectric materials, zinc oxide crystals generate an
electrical charge in response to heat or force. One of these crystals produces
an electrical charge when sound is delivered, disrupting surrounding electric
fields. The magnetic disturbance can travel across a vacuum from one crystal to
another if they are in the same electric field. The receiving crystal can
transform the disturbance back into sound on the opposite side by mirroring the
sound waves' frequency.
Potential Applications and Restrictions
There are limitations to sound transmission. The
interruptions are limited to a distance equal to one sound wave's wavelength.
Furthermore, in a few of the studies, there was some wave distortion or
reflection, indicating that the sound was not perfectly transmitted between the
crystals.
On the other hand, there were times when the crystals
flawlessly conveyed the full sound wave. Co-author of the study Ilari Maasilta,
a material physicist at the University of Jyväskylä in Finland, said, "In
most cases the effect [sound transmitted] is small, but we also found
situations, where the full energy of the wave jumps across the vacuum with 100%
efficiency, without any reflections."
The advancement of microelectromechanical components, which
are present in many contemporary technology, including smartphones, could
benefit from this research.