The key to making lasers work is the concept of "stimulated emission". When you have a population inversion - a larger number of atoms / molecules in an excited state than in the corresponding ground state - you can tap into their energy by stimulation emission. When such an atom/molecule is excited with a photon with energy corresponding to the transition, it emits a photon that is perfectly in phase with the incident photon.

In this way you get two photons that are in phase, and traveling in the same direction. This mechanism results in a beautiful amplification, and a coherent beam of light.

There is no analog (that I can think of) for stimulated emission of gravity waves - and so a GASER (gravity amplification by stimulated emission of radiation) is fundamentally impossible AFAIK. Fundamentally, a massive system (potential emitter of gravity waves) cannot be in an "excited" state from which emission is possible by excitation with another gravity wave.

The key to making lasers work is the concept of "stimulated emission". When you have a population inversion - a larger number of atoms / molecules in an excited state than in the corresponding ground state - you can tap into their energy by stimulation emission. When such an atom/molecule is excited with a photon with energy corresponding to the transition, it emits a photon that is perfectly in phase with the incident photon.

In this way you get two photons that are in phase, and traveling in the same direction. This mechanism results in a beautiful amplification, and a coherent beam of light.

There is no analog (that I can think of) for stimulated emission of gravitational waves - and so a GASER (gravity amplification by stimulated emission of radiation) is fundamentally impossible AFAIK. Fundamentally, a massive system (potential emitter of gravitational waves) cannot be in an "excited" state from which emission is possible by excitation with another gravitational wave.