Vacuum-tube

Vacuum tubes are electronic components, where the current circulating on one wire controls either: (1) the strength of a current on a second wire; or (2) whether there is a current on a second wire Vacuum tubes that control the strength of the current on a second wire are still useful in audio equipment, like amplifiers.

Vacuum tubes that controlled whether there was or wasn't a current on a wire were crucial in the development of the first electronic computers, in the 1940s and early 1950s. ENIAC, an early computer, required 10,000 vacuum tubes.

The use of vacuum tubes, in electronic computers, disappeared after the development of solid-state electronics, particularly the transistor, and, later, integrated circuits.

During the cold war, when fighter pilots, defecting from Soviet bloc countries, landed their fighter jets, Soviet technological expertise was mocked, because these fighters continued to use tubes, in some of their components. Better informed commentators speculated that while Soviet designs could have used solid state electronics, Soviet designers particular chose to use tubes, because tubes were much more resistant to being knocked out by an electro magnetic pulse (EMP). Explosions of nuclear weapon are very bright, blindingly bright. They are bright across the spectrum, from x-rays that induce mutations, to radio waves. The burst of radio waves from a nuclear explosion is so powerful it can instantly induce a very strong current in power transmission wires, and even in the electrical paths within a high density integrated circuit. The EMP pulse is capable of shorting out electronic devices, even at considerable distance from the explosion.

Commentators suggested the Soviets imagined battlefields, where a nuclear explosion's EMP would short out all Western fighters, causing them to crash, while Soviet fighters would remain airborne.