We are not alone: Extraterrestrial Technological Life in our Galaxy
Department of Planetary Sciences Lunar and Planetary Laboratory University of Arizona Tucson, Arizona, USA
- *Corresponding Author:
- Strom RG
Department of Planetary Sciences Lunar and Planetary
Laboratory University of Arizona Tucson, Arizona, USA
Tel: +39 348 2650891
E-mail: [email protected]
Received date: September 27, 2015 Accepted date: October 31, 2015 Published date: November 3, 2015
Citation: Strom RG (2015) We are not alone: Extraterrestrial Technological Life in our Galaxy. Astrobiol Outreach 3:144. doi: 10.4172/2332-2519.1000144
Copyright: © 2015 Strom RG. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
This paper is an evaluation of the number of technological civilizations presently in our Milky Way galaxy. The current estimate of the present number of Earth-like planets (± 25% of Earth’s radius) in the habitable region of Sunlike stars is about 6.6 billion. Using a modified Drake Equation, “optimistic”, “pessimistic” and “unlikely” estimates of six constraints indicate that about 40,000 technological civilizations are presently in our galaxy for a “pessimistic evaluation”. Even “unlikely” values that are half the “pessimistic” values give over 600 technological civilizations in the galaxy. It would take a completely unrealistic value of 2.5% for each constraint to get just 1 technology (us). “Therefore, we are almost surely not alone in our Milky Way galaxy”. Furthermore, almost all of the extra-solar system technologies are probably much further advanced than ours, i.e., they probably began thousands to millions of years before our Industrial Revolution. It is possible, but highly uncertain, that we have been visited by one or more of these civilizations.