20 Modern Systems Still Running on Old Tech

That familiar hum from the kitchen hides a piece of wartime engineering. At the heart of most conventional microwave ovens sits a magnetron, a specialized vacuum tube that generates high-power microwave energy. Magnetrons were developed before and during World War II because compact high-frequency radar could give Allied aircraft far better detection capabilities. Although solid-state electronics have replaced vacuum tubes almost everywhere else in consumer life, and solid-state microwave cooking systems do exist, the magnetron remains difficult to dislodge from ordinary ovens because it produces a great deal of radio-frequency power very cheaply and efficiently.