We Are Not AloneNational Geographic, March 20191

“There are infinite worlds both like and unlike this world of ours…we must believe that in all worlds there are living creatures and plants and other things we see in this world.” – Epicurus.


The March 2019 issue of National Geographic includes this article which updates us on the scientific efforts at finding evidence of life on other worlds and particularly intelligent life (known as SETI or Search for Extraterrestrial Intelligence). For over 50 years scientists have been using radiotelescopes to scan the heavens for evidence of radio signals from other advanced civilizations without success. However the existence of other planets was confirmed in 1995, when 51 Pegasi b was discovered. Using the now silent Keppler Space Telescope. Over 4000 exoplanets (planets outside our solar system) have since been identified with about 25% being earth-sized and in the habitable zone of their stars. Projecting the Keppler data, there should be at least 25 billion such planets in our galaxy alone.

Current efforts at finding alien life are now directed at identifying biosignatures -physicochemical features consistent with life such as atmospheric oxygen and methane – and technosignatures –similar analyses suggesting civilization such as presence of pollutants – on exoplanets. There is also interest in sending tiny computers powered by solar sails to the nearest star systems. (The reader is referred to the article itself for more detail.) The author, Jamie Shreeve, closes with the titillating phrase, “… the first intimation of life from a distant planet feels thrillingly close.”

For the most part the article avoids the philosophical implications of the eventual demonstration of life and intelligence beyond Earth, but in an amazing coincidence, last week I happened upon a book at New Haven Books in Melbourne, Florida, titled Are We Alone?2, by Paul Davies, an Australian professor of natural philosophy, published in 1995. Davies explores the history of speculation on life beyond Earth, openly discussed by the ancient Greek atomists such as Epicurus (see quote above). In the seventeenth century, Richard Bentley reasoned God would not have made so many stars invisible to the naked eye for us, but rather for their nearby inhabitants, while Christiaan Huygens thought it befit the deity to endow other worlds with intelligent life. More recently people have been intrigued by the possibility that UFOs are evidence of aliens from other star systems

(continued next post)

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