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[ti:Are There Strangers in Space?]
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[00:00.55]Lesson 43
[00:03.12]Are there strangers in space?
[00:11.44]What does the 'uniquely rational way' for us to communicate with other intelligent beings in space depend on?
[00:22.80]We must conclude from the work of those who have studied the origin of life,
[00:28.36]that given a planet only approximately like our own, life is almost certain to start.
[00:36.13]Of all the planets in our solar system, we are now pretty certain the Earth is the only one on which life can survive.
[00:46.40]Mars is too dry and poor in oxygen, Venus far too hot, and so is Mercury,
[00:54.04]and the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres.
[01:02.12]But other suns, start as the astronomers call them, are bound to have planets like our own, and as is the number of stars in the universe is so vast,
[01:14.38]this possibility becomes virtual certainty.
[01:18.33]There are one hundred thousand million starts in our own Milky Way alone,
[01:24.73]and then there are three thousand million other milky ways or galaxies, in the universe.
[01:32.54]so the number of stars that we know exist is now estimated at about 300 million million million.
[01:43.29]Although perhaps only 1 percent of the life that has started somewhere will develop into highly complex and intelligent patterns,