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Carl Sagan on the Existence of Extraterrestrials

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Carl Sagan discusses the incomprehensible vastness of the universe, the wonder of our own place in it all, and the science behind understanding the likelihood of the existence of extraterrestrial beings.
Executive Producer David Gerlach
Director Kirill Yeretsky
Series Producer Amy Drozdowska

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Carl Sagan argues that if we were to receive a message from an extraterrestrial civilization, the civilization would have to be far more sophisticated and technologically advanced than our's. What evidence does he use to back this up?

a

Humans have only existed for a tiny, almost imperceptible percentage of the universe's history, so another life form may have started evolving much earlier than us.

b

On the scale of human history, we only just invented radio telescopes, so we wouldn't be able to receive messages from anyone less advanced than us because they wouldn't have invented the technology to send these messages yet.

c

Human spaceship technology has not advanced very far.

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