The theremin an early untouchable unique electronic instrument

The Theremin named after the Russian physicist Leon Theremin ( Lev Termin in Russian) is an early electronic musical instrument somewhat unique in that it is played without physical contact.

As Wikipedia describes the theremin's control:

The instrument's controlling section usually consists of two metal antennas that sense the relative position of the thereminist's hands and control oscillators for frequency with one hand, and amplitude (volume) with the other. The electric signals from the theremin are amplified and sent to a loudspeaker.Here is an early clip of Theremin demonstrating the instrument:

Theremin was an inventive genius and was working on wireless TV between 1925 to 1927: "During this time Theremin was also working on a wireless television with 16 scan lines in 1925, improving to 32 scan lines and then 64 using interlacing in 1926, and he demonstrated moving, if blurry, images on 7 June 1927.[19]"

Theremin's invention of the Theremin was virtually accidental. He was doing Soviet government sponsored research into proximity sensors. He noticed that when he moved his hand closer to a unit that the sound changed. This was in October 1920. He made a lengthy tour of Europe demonstrating his instrument to packed houses. Theremin subsequently move to the United States where he patented the Theremin in 1928. He eventually sold rights to the Theremin to RCA.

The Theremin has featured in many movie soundtracks such as Spellbound and the Day the Earth Stood Still. The complex opening theme of the Earth Stood Still uses two Theremins among many other instruments:

Although the Theremin failed commercially there were still performers who were able to draw crowds to hear it and a number of composers created music for it. The theme of the television drama Midsomer Murders also features the Theremin as shown on the appended video:

Theremin made an abrupt return to the Soviet Union from the United States in 1938. There were various stories about why he left. Some people claimed he was simply homesick. Others believe he had been kidnapped by Soviet officials. Theremin's wife at the time Livania claimed he had been kidnapped from his studio by some Russians and she felt he would be taken out of the country. The real reason Theremin left was due to tax and financial problems in the US. No doubt his wife's story was designed to keep debt collectors away!

However, not long after he returned to the USSR he was imprisoned and sent to work in Kolyma gold mines. However, there were many rumours he had been executed. In fact, Theremin was put to work not in the gold mines but in a secret lab that was part of the system. The Soviet Union rehabilitated him in 1956.

Apparently Theremin's talents were put to work by the USSR while in prison as he invented a listening device called The Thing:Theremin invented another listening device called The Thing. Disguised in a replica of the Great Seal of the United States carved in wood, in 1945 Soviet school children presented the concealed bug to U.S. Ambassador as a "gesture of friendship" to the USSR's World War II ally. It hung in the ambassador’s residential office in Moscow and intercepted confidential conversations there during the first seven years of the Cold War, until it was accidentally discovered in 1952.[29]

Theremin visited the United States again in 1991. He ended up dying in Moscow at the ripe old age of 97 in 1993.

After the end of the Second World War, the Theremin began to fall into disuse as newer electronic instruments were introduced and were much easier to play. It still remained of interest to a few electronics enthusiasts, including Robert Moog who began building Theremins in the 1950's while still a high school student. Moog claimed that what he learned from the experience helped his create the famous Moog Synthesizer. The release of the award winning film "Theremin: An Electronic Odyssey" in 1994 revived interest in the Theremin. The music critic Harold Schonberg claims that the theremin sound is like "a cello lost in dense fog, crying because it does not know how to get home".

There are many different type of Theremin. On 20 July 2013, a group of 272 theremin players (Matryomin ensemble) in Hamamatsu, Shizuoka, Japan, achieved a Guinness world record as the largest theremin ensemble. The name Matryomin is from the words matryoshka, the Russian dolls, and theremin.