Extraterrestrials and Evolution

I have been perplexed by the strong belief in extraterrestrial life among prominent cosmologists, especially Carl Sagan and Michio Kaku -- even though there is no evidence to support that belief. I understand the argument: the number of Earth-like planets in the universe must be so enormous that many of them must be inhabited by life. Yet our best efforts have failed to find evidence of the existence of such life.

Then a retired chemistry teacher I know mentioned that life should evolve on other planets in the same way it had evolved on Earth. I began to understand. Life on Earth is believed to have evolved from inanimate matter. The theory of evolution would be strengthened if we could show that life had also evolved elsewhere in the universe.

Then is the theory of evolution weakened by our failure to find any trace of life elsewhere in the universe?

Eugene Paul