Originally Posted by Negotiator
"Open to the possibility of extra-terrestrial life in the universe, but skeptical of the proposed alien origin of UFO's due to a lack of strong physical evidence that would support this hypothesis."
This is the same dude's take on UFO.
It's funny you point that out. I really don't know anything about Jastrow, but the idea you presented about ET is similar to my idea. I don't know if God placed life on other planets, asteroids, moons, etc.
But if there is no other life than that on Earth, when mankind does make a foothold on other planets, moons, asteroids, etc., at least we wouldn't have to be concerned about competition with alien life (microbial, intelligent, or otherwise). If there is no other life, then there wouldn't be an ecological question about just taking what we want and leaving the rest.
And, even if there is ET life, I doubt they would be visiting us, and especially it seems unlikely they would hide their existence (unless it was that they feared us).