This is a clip from a conversation with Sean Carroll on the Artificial Intelligence podcast. You can watch the full conversation here: http://bit.ly/315QhfC If you enjoy these, consider subscribing, sharing, and commenting below.

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Sean Carroll is a theoretical physicist at Caltech, specializing in quantum mechanics, gravity, and cosmology. He is the author of several popular books: one on the arrow of time called From Eternity to Here, one on the Higgs boson called The Particle at the End of the Universe, and one on science and philosophy called The Big Picture: On the Origins of Life, Meaning, and the Universe Itself. He has an upcoming book on Quantum Mechanics that you can preorder now called Something Deeply Hidden. He writes one of my favorite blogs on his website preposterousuniverse.com. I recommend clicking on the Greatest Hits link that lists accessible, interesting posts on the arrow of time, dark matter, dark energy, the Big Bang, general relativity, string theory, quantum mechanics, and meta questions about the philosophy of science, God, Ethics, Politics, Academia, and much much more. Finally, and perhaps most famously, he is the host of a podcast called Mindscape that you should subscribe to and support on Patreon.

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Do you think there's intelligent life, however you would like to define intelligent life, out there in the universe?

My guess is that there is not intelligent life in the observable universe other than us, simply on the basis of the fact that the likely number of other intelligent species in the observable universe, there's 2 likely numbers, 0 or billions.

And if there had been billions, you would have noticed already.

For there to be literally like a small number, like Star Trek, there's a dozen intelligent civilizations in our galaxy, but not a billion?

It's easy for me to imagine that there are 0 others because there's just a big bottleneck to making multicellular life or technological life or whatever.

It's very hard for me to imagine that there's a whole bunch out there that have somehow remained hidden from us.

The question I'd like to ask is what would intelligent life look like?

What I mean by that question and where it's going is what if intelligent life is just fundamentalist, in some very big ways different than the 1 that has on Earth.

That there's all kinds of intelligent life that operates in different scales of both size and temporal.

That's a great possibility because I think we should be humble about what intelligence is, what life is.

We don't even agree on what life is, much less what intelligent life is, right?

So that's an argument for humility saying there could be intelligent life of a very different character, right?

Like you could imagine the dolphins are intelligent but never invent space travel because they live in the ocean and they don't have thumbs, right?

So they never invent technology, they never invent smelting.

Maybe the universe is full of intelligent species that just don't make technology.

That's compatible with the data, I think.

And I think maybe what you're pointing at is even more out there versions of intelligence, you know, intelligence in intermolecular clouds or on the surface of a neutron star or in between the galaxies and giant things where the equivalent of a heartbeat is 100 million years.

On the 1 hand, yes, we should be very open minded about those things.

On the other hand, we all all of us share the same laws of physics.

There might be something about the laws of physics, even though we don't currently know exactly what that thing would be that makes meters and years the right length and time scales for intelligent life.

It's not impossible to me that there's a sweet spot for intelligent life that we find ourselves in.

I'm open-minded either being humble and there's all sorts of different kinds of life, or no, there's a reason we just don't know it yet why life like ours is the kind of life that's out there.

Yeah, I'm of 2 minds too, but I often wonder if our brains is just designed to, quite obviously, to operate and see the world in these time scales, and we're almost blind, and the tools we've created for detecting things are blind to the kind of observation needed to see intelligent life at other scales.

Well I'm totally open to that, but so here's another argument I would make.

You know, we have looked for intelligent life, but we've looked at for it in the dumbest way we can, right, by turning radio telescopes to the sky.

And why in the world would a super advanced civilization randomly beam out radio signals wastefully in all directions into the universe?

That just doesn't make any sense, especially because in order to think that you would actually contact another civilization, you would have to do it forever.

You'd have to keep doing it for millions of years.

If you thought that There were other solar systems with planets around them where maybe intelligent life didn't yet exist but might someday.

You wouldn't try to talk to it with radio waves.

You would send a spacecraft out there and you would park it around there.

And it would be like, from our point of view, be like 2001, where there's an, you know, and monolith,

In fact, the other way works also, right?

There could be artifacts in our solar system that are have been put there by other technologically advanced civilizations.

And that's how we will eventually contact them.

We just haven't explored the solar system well enough yet to find them.

The reason why we don't think about that is because we're young and impatient, right?

Like it would take more than my lifetime to actually send something to another star system and wait for it and then come back.

So but if we start thinking on hundreds of thousands of years or million-year time scales, that's clearly the right thing to do.


Speaker 0: Do you think there's intelligent life, however you would like to define intelligent life, out there in the universe?

Speaker 1: My guess is that there is not intelligent life in the observable universe other than us, simply on the basis of the fact that the likely number of other intelligent species in the observable universe, there's 2 likely numbers, 0 or billions. And if there had been billions, you would have noticed already. For there to be literally like a small number, like Star Trek, there's a dozen intelligent civilizations in our galaxy, but not a billion? That's weird. That's sort of bizarre to me.

It's easy for me to imagine that there are 0 others because there's just a big bottleneck to making multicellular life or technological life or whatever. It's very hard for me to imagine that there's a whole bunch out there that have somehow remained hidden from us.

Speaker 0: The question I'd like to ask is what would intelligent life look like? What I mean by that question and where it's going is what if intelligent life is just fundamentalist, in some very big ways different than the 1 that has on Earth. That there's all kinds of intelligent life that operates in different scales of both size and temporal.

Speaker 1: Right. That's a great possibility because I think we should be humble about what intelligence is, what life is. We don't even agree on what life is, much less what intelligent life is, right? So that's an argument for humility saying there could be intelligent life of a very different character, right? Like you could imagine the dolphins are intelligent but never invent space travel because they live in the ocean and they don't have thumbs, right?

So they never invent technology, they never invent smelting. Maybe the universe is full of intelligent species that just don't make technology. That's compatible with the data, I think. And I think maybe what you're pointing at is even more out there versions of intelligence, you know, intelligence in intermolecular clouds or on the surface of a neutron star or in between the galaxies and giant things where the equivalent of a heartbeat is 100 million years. On the 1 hand, yes, we should be very open minded about those things.

On the other hand, we all all of us share the same laws of physics. There might be something about the laws of physics, even though we don't currently know exactly what that thing would be that makes meters and years the right length and time scales for intelligent life. Maybe not. But we're made of atoms. Atoms have a certain size.

We orbit stars. Stars have a certain lifetime. It's not impossible to me that there's a sweet spot for intelligent life that we find ourselves in. So I'm open-minded in either way. I'm open-minded either being humble and there's all sorts of different kinds of life, or no, there's a reason we just don't know it yet why life like ours is the kind of life that's out there.

Speaker 0: Yeah, I'm of 2 minds too, but I often wonder if our brains is just designed to, quite obviously, to operate and see the world in these time scales, and we're almost blind, and the tools we've created for detecting things are blind to the kind of observation needed to see intelligent life at other scales.

Speaker 1: Well I'm totally open to that, but so here's another argument I would make. You know, we have looked for intelligent life, but we've looked at for it in the dumbest way we can, right, by turning radio telescopes to the sky. And why in the world would a super advanced civilization randomly beam out radio signals wastefully in all directions into the universe? That just doesn't make any sense, especially because in order to think that you would actually contact another civilization, you would have to do it forever. You'd have to keep doing it for millions of years.

That sounds like a waste of resources. If you thought that There were other solar systems with planets around them where maybe intelligent life didn't yet exist but might someday. You wouldn't try to talk to it with radio waves. You would send a spacecraft out there and you would park it around there. And it would be like, from our point of view, be like 2001, where there's an, you know, and monolith,

Speaker 0: monolith,

Speaker 1: though there could be an artifact. In fact, the other way works also, right? There could be artifacts in our solar system that are have been put there by other technologically advanced civilizations. And that's how we will eventually contact them. We just haven't explored the solar system well enough yet to find them.

The reason why we don't think about that is because we're young and impatient, right? Like it would take more than my lifetime to actually send something to another star system and wait for it and then come back. So but if we start thinking on hundreds of thousands of years or million-year time scales, that's clearly the right thing to do.

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Sean Carroll: Is There Intelligent Life Out There in the Universe? | AI Podcast Clips