Maser

The MASER emerged from the collision of Cold War physics programs on opposite sides of the Iron Curtain. In May 1952, Nikolay Basov and Alexander Prokhorov presented theoretical framework for "molecular generators" in Moscow. One month later, Joseph Weber independently described similar principles in Ottawa. Yet Charles Townes at Columbia University transformed theory into hardware.

Townes recounted the breakthrough came on a park bench in Washington, D.C. in 1951, where he sketched the core concept: use ammonia molecules to amplify microwaves through stimulated emission. By 1953, working with James Gordon and Herbert Zeiger, Townes built the first working ammonia maser, producing coherent radiation at 24 gigahertz. They coined MASER: Microwave Amplification by Stimulated Emission of Radiation.

The physics predated its inventors by decades. In 1917, Albert Einstein—taking a detour from general relativity—introduced spontaneous and stimulated emission. A photon at the right frequency could induce an excited atom to release a second photon with identical phase, frequency, and direction. For three decades, this remained theoretical curiosity.

The maser required population inversion—more atoms in excited states than ground states, defying thermal equilibrium. Townes achieved this by passing ammonia through an electrostatic separator, filtering out lower-energy molecules before they entered a resonant cavity. The 1964 Nobel Prize recognized both achievements: Townes received half, Basov and Prokhorov shared the other half.

From microwave to optical maser took six more years. In 1958, Townes and Arthur Schawlow proposed an "optical maser" using parallel mirrors with amplifying medium between them. But Theodore Maiman at Hughes rejected conventional wisdom. On May 16, 1960, his ruby laser emitted the first coherent light beam with a $50,000 budget.

Today, hydrogen masers serve as atomic timekeeping's heartbeat, losing only one second every three million years. NASA's Deep Space Network relies on them. The maser's trajectory illustrates how inventions percolate—Einstein's 1917 theory lay dormant until quantum mechanics matured and WWII radar advanced microwave engineering.