I think Quote by Bill Watterson

The surest sign that intelligent life exists somewhere else in the universe is that it has never tried to contact us.

— Young Siddiq Prince

The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us.

— Bill Watterson

I was reading about how countless species are being pushed toward extinction by man's destruction of forests. . . . Sometimes I think the…

— Bill Watterson

That intelligent creatures exist in outerspace is proven by the fact that they have not contacted us.

— Loesje

I wonder if, in fact, we have been observed by aliens and upon close examination of human conduct and human behavior they have concluded…

— Neil deGrasse Tyson

The best proof that there's intelligent life in the universe is that it hasn't come here.

— Arthur C. Clarke

Perhaps, as some wit remarked, the best proof that there is Intelligent Life in Outer Space is the fact it hasn't come here. Well,…

— Arthur C. Clarke

Perhaps we've never been visited by aliens because they have looked upon Earth and decided there's no sign of intelligent life.

— Neil deGrasse Tyson

If we ever established contact with intelligent life on another world, there would be barriers to communication. First, they would be many light years…

— Martin Rees

Even if there is intelligent life somewhere, which perhaps there is, I'm agnostic about it, I don't know.

— Luka Jones

I think there's all kinds of life out there, including intelligent life, but the reason we haven't found each other is because of vast…

— Leroy Chiao

Intelligent life can't be all that common because it's really rare on Earth and especially since we define ourselves to be intelligent. But in…

— Neil deGrasse Tyson