Optimal wavelength region for communication with extraterrestrial intelligence: λ = 1.5 mm


This article shows that the best capability and reliability of communication at astronomical distances can be achieved at millimetre wavelengths. The cost of communication, and the number of directions in which signals are sent and searched for are assumed to be fixed. A characteristic frequency might be 203.385 GHz, corresponding to the splitting of the ground state of the lightest atom—positronium—and coinciding with the centroid of the relic background spectrum.

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Kardashev, N. Optimal wavelength region for communication with extraterrestrial intelligence: λ = 1.5 mm. Nature 278, 28–30 (1979). https://doi.org/10.1038/278028a0

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