# The Laser * Charles Townes * [[1948]] — Idea of population inversion * [[1951]] — Molecular beam separation + the idea of the maser * [[1954]] — The Maser * [[1955]] — properties of the maser * [[1960]] — Ruby Laser “Townes reports that several eminent physicists—among them [Niels Bohr](https://en.wikipedia.org/wiki/Niels_Bohr) , [John von Neumann](https://en.wikipedia.org/wiki/John_von_Neumann) , and [Llewellyn Thomas](https://en.wikipedia.org/wiki/Llewellyn_Thomas) —argued the maser violated Heisenberg’s [uncertainty principle](https://en.wikipedia.org/wiki/Uncertainty_principle) and hence could not work. “ [Web URL for this note](http://notes.benjaminreinhardt.com/The+Laser) [Comment on this note](http://via.hypothes.is/http://notes.benjaminreinhardt.com/The+Laser)