It can be a challenge for some sound-making machines to be understood via video. Sometimes there’s no way to truly understand how it’s working without the experience of playing it. The theremin, patented in 1928 and played above by its Russian inventor Léon Theremin, is one such instrument.
The controlling section usually consists of two metal antennas which sense the position of the player’s hands and control oscillators for frequency with one hand, and amplitude (volume) with the other, so it can be played without being touched. The electric signals from the theremin are amplified and sent to a loudspeaker.
Still fascinating to watch, however, especially when played by the inventor. This video, and many others are featured in io9’s The Oddest-Looking Musical Instruments on Earth. And/or there are more inventions and instruments in the archives.
Rotating Saddle (and the science behind it) from the NatSciDemos team:
A playground ball finds stability in a saddle when the saddle is rotating at the proper speed.
Mechanical analog of a “Paul Trap” particle confinement—a ball is trapped in a time-varying quadrupole gravitational potential. A large saddle shape (attached to a plywood disk) is mounted on a multi-purpose turntable. The saddle shape is essentially a quadrupole gravitational potential. Rotation of this potential subjects the ball to an alternating repulsive and attractive potential, much like the time-varying electric quadrupole potential of a Paul Trap used in trapping single ions or electrons.
The plastic ball used here is about 25 cm in diameter and was purchased at a toy store. The saddle consists of many layers of fiberglass and was hand-made with help from Justin Georgi. The turntable is driven at about 110 rpm with a DC motor. We have observed this ball at this speed remaining stable for over 2 hours.
It’s not magic, kiddo. It’s science!
Sulfur hexafluoride (SF6) is a colorless, odorless gas that is more dense than air at 6.12 g/L (at sea level). This density is why you can pour it into a glass container and float a light-weight aluminum “boat” on its gas “sea.” Watch this demonstration at the Physikshow of the University of Bonn!