While some contend that there could exist extraterrestrial civilizations that have been around for a billion years and therefore a billion years more advanced than us, others stand by the Fermi Paradox which asserts if they were out there we would have heard from them.

If there are old civilizations out there, I wonder what one billion year generation iPhones look like.

Fermi reasoned, if there are other advanced extraterrestrial civilizations, then why is there no evidence of such, like spacecraft or probes floating around the Milky Way. His question became famously known as the Fermi Paradox. The paradox is the contradiction between the high estimates of the probability of the existence of extraterrestrial civilizations and yet the lack of evidence for, or contact with, any such civilizations.

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