In this 1979 article, Bernard M. Oliver (1916 – 1995) builds up on the suggestion of Cocconi and Morrison (1959), and the work of the Cyclops study (Oliver and Billingham, 1973) to suggest that the region bound by the Hydrogen and Hydroxl lines (1420 – 1660 MHz) should be the prime frequency band for our search for extra – terrestrial intelligence. This region bounded by the ‘water’ band, has since been called the water hole, an allusion to a watering hole.
- Oliver starts off by my making the case for electromagnetic (EM) waves are the most practical (fastest and most energy efficient) way to interact with extra-terrestrial civilizations under the current technological limitations. This is mainly due to their zero mass, and travel speed (celeritas).
- Then, estimating the noise contribution from the non thermal background, and the cosmic microwave background (CMB) radiation, and collating that with the absorption features (mainly the water molecules in the atmosphere), he concludes that the ~ 1 GHz to ~ 10 GHz window is the preferred spectrum for us to search for ET signals.
- Citing the Cyclops study, he concludes that the region between Hydrogen and Hydroxl ions would be the best band to look at it, due to the significance of water for harbouring life.
Is this really the best place to look in?
I think this paper was assigned to us to understand the details associated with choosing this particular radio band, as the preferred means of communication and search, and its significance. It is important to understand the historical and scientific background for today’s SETI searches looking for extraterrestrial intelligence around this interstellar watering hole.