Lesson 43
Are there strangers in space?
What does the 'uniquely rational way' for us to communicate with other intelligent beings in space depend on?
We must conclude from the work of those who have studied the origin of life,
that given a planet only approximately like our own, life is almost certain to start.
Of all the planets in our solar system, we are now pretty certain the Earth is the only one on which life can survive.
Mars is too dry and poor in oxygen, Venus far too hot, and so is Mercury,
and the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres.
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,
this possibility becomes virtual certainty.
There are one hundred thousand million starts in our own Milky Way alone,
and then there are three thousand million other milky ways or galaxies, in the universe.
so the number of stars that we know exist is now estimated at about 300 million million million.
Although perhaps only 1 percent of the life that has started somewhere will develop into highly complex and intelligent patterns,
so vast is the number of planets, that intelligent life is bound to be a natural part of the universe.
If then we are so certain that other intelligent life exists in the universe, why have we had no visitors from outer space yet?
First of all, they may have come to this planet of ours thousands or millions of years ago,
and found our then prevailing primitive state completely uninteresting to their own advanced knowledge.
Professor Ronald Bracewell, a leading American radio astronomer,
argued in Nature that such a superior civilization, on a visit to our own solar system,