In one minute

Gertsenshtein estimates gravitational radiation excited when light travels through an external electromagnetic field, using weak-field general relativity. He isolates the resonant interference term in the electromagnetic stress-energy tensor and solves for slowly varying wave amplitudes. In a constant field with little absorption or scattering, the induced gravitational-wave amplitude accumulates with the transit time. For randomly changing field domains, the contributions instead combine incoherently in energy. An interstellar example with a ten-microgauss field, ten-light-year correlation length and ten million years of travel gives an energy conversion ratio near ten to the minus seventeen; the generated frequency follows the light. He also discusses stellar interiors and mentions inverse conversion into light, presenting a theoretical estimate rather than an experimental demonstration.

Wave Resonance of Light and Gravitational Waves