“Perhaps, in retrospect, there would be little motivation even for malevolent extraterrestrials to attack the Earth; perhaps, after a preliminary survey, they might decide it is more expedient just to be patient for a little while and wait for us to self-destruct.”

“The chance of receiving a signal from a civilization exactly as advanced as we are should be minuscule. If they were even a little behind us, they would lack the technological capability to communicate with us at all. So the most likely signal would come from a civilization much more advanced.”

“You might imagine an uncharitable extraterrestrial observer looking down on our species... - with us excitedly chattering, "The Universe is created for us! We're at the center! Everything pays homage to us!" - and concluding that our pretensions are amusing, our aspirations pathetic, that this must be the planet of the idiots.”

“Arguments from authority carry little weight – authorities have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts.”

“Long ago, when an early galaxy began to pour light out into the surrounding darkness, no witness could have known that billions of years later some remote clumps of rock and metal, ice and organic molecules would fall together to make place called Earth; or that life would arise and thinking beings evolve who would one day capture a little of that galactic light, and try to puzzle out what had sent it on its way. And after the earth dies, some 5 billion years from now, after it's burned to a crisp, or even swallowed by the Sun, there will be other worlds and stars and galaxies coming into being -- and they will know nothing of a place once called Earth.”

“An extraterrestrial being, newly arrived on Earth - scrutinizing what we mainly present to our children in television, radio, movies, newspapers, magazines, the comics, and many books - might easily conclude that we are intent on teaching them murder, rape, cruelty, superstition, credulity, and consumerism. We keep at it, and through constant repetition many of them finally get it.”

“I'm frequently asked, "Do you believe there's extraterrestrial intelligence?" I give the standard arguments- there are a lot of places out there, the molecules of life are everywhere, I use the word billions, and so on. Then I say it would be astonishing to me if there weren't extraterrestrial intelligence, but of course there is as yet no compelling evidence for it.Often, I'm asked next, "What do you really think?"I say, "I just told you what I really think.""Yes, but what's your gut feeling?"But I try not to think with my gut. If I'm serious about understanding the world, thinking with anything besides my brain, as tempting as that might be, is likely to get me into trouble. Really, it's okay to reserve judgment until the evidence is in.”