Charles
Somebody wrote the below on another list.
But still this is not the original discussion which is about the existence or not of other intelligent lifeforms in the universe. I can agree that perhaps no civilization can escape its resource limits and star travel which would explain there abscence from the skies. But that is not proof they do not exist. One the other hand we know we do exist, and our planrt is nothing exceptional and if we exist there must be others. To accept that we are the only ones in the universe is illogical, egocentric, and against the laws of nature. Since the laws of physics, chemistry and biochemistry produced us and since we must assume these laws operate the same way everywhere then we are an emergent property of those laws and therefore there must be other such lifeforms in other places. Whether we will ever detect them or be detected by them is another question.