Sentences with phrase «number of technological civilizations»
On the other hand, if there are 100 billion suitable planets in our galaxy, if the origin of life is highly probable, if there are billions of years of evolution available on each such planet and if even a small fraction of technical civilizations pass safely through the early stages of technological adolescence, the number of technological civilizations in the galaxy today might be very large.
https://www.scientificamerican.com/ Not exact matches
Given the magnitude and number of extreme technological and economic challenges that must be overcome to achieve starflight, it's difficult to imagine what, in fact, a civilization capable of interstellar travel would look like.