Frank Rathburn, age 14, of Poughkeepsie, N.Y., for his question:

WHAT IS A MASER?

Maser is an acronym for microwave amplication by stimulated emission of radiation. It is a device that amplifies or generates microwaves or radio waves. A maser producing radiation in the optical region is called a laser.

As in lasers, amplification of radiation in masers is obtained by stimulated emission. This occurs when a photon induces an excited atom or molecule to fall to a lower energy state while emitting a photon of the same frequency as the incoming photon.

The emitted photon travels in the same direction and in phases with the incoming photon, which is not absorbed during the interaction. The amplitudes of the two waves add up and amplification of the incoming wave has taken place.

Masers make use of those transitions in molecules or crystals that correspond to the energies of microwave or radio frequencies.

The first maser oscillator was developed by three American physicists named Charles Townes, James Gordon and Herbert Zeiger in 1954.