Charles Townes 1915-2015

One of the neatest astronomical discoveries was the discovery of ammonia molecules at the center of the Milky Way. In 1968, Charles Townes and his colleagues detected the microwave emission at a wavelength of 1.25 cm, and showed that it was due to a cloud of ammonia at 23 K near the galactic center.

Stereo-model of tetrahedral ammonia.

Townes won the Nobel Prize in Physics, 1964,

"for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle."

In fact, he had worked on ammonia masers in the laboratory in the 1950s, and proposed the laser in a 1958 paper titled "Infrared and optical masers" with Arthur Schawlow. And it was the very next year, in 1959, that Theodore Maiman built the first laser. Here is a nice article on the history of the laser.

The name "optical maser" never caught on, and it's probably a good thing. Can you imagine? "His optical maser-like focus was on the bottom line."

Charles Townes recently died on 27.Jan.2015, and there is a short obituary here, and a longer one here.

For more than you ever wanted to know about interstellar ammonia, read this review article by Ho and Townes.