#1596 - Avi Loeb

**Joe Rogan** (0:04)
The Joe Rogan Experience.

**Avi Loeb** (0:15)
Thanks for having me.

**Joe Rogan** (0:17)
My pleasure. I'm very good friends with your friend, Lex Friedman, and he highly recommends you as well.

**Avi Loeb** (0:24)
Oh, thank you. You know, he asked me about social media, and I told him I have no footprint on social media. He said, why?
And I said, I promised my wife when I married her not to have any account, and he said, I should get married.

**Joe Rogan** (0:40)
Yeah, he reads accounts.
He says he doesn't, but then he does. He reads comments and stuff, and then he gets mad at things people say. It's kind of funny.

**Avi Loeb** (0:48)
You see, I save the time. I don't even read what other people say.

**Joe Rogan** (0:51)
Good for you.

**Avi Loeb** (0:52)
And I don't care how many likes I have. That's the other thing.

**Joe Rogan** (0:54)
That's wonderful. That's a freedom.
That's an underrated freedom. Yeah. You came on my radar when you were discussing ʻOumuamua, is that what I said?

**Avi Loeb** (1:05)
Yes, that's the right thing.

**Joe Rogan** (1:05)
ʻOumuamua, which is an object that we detected in space that you believe could possibly have been extraterrestrial in origin, meaning from some sort of a civilization.

**Avi Loeb** (1:17)
Right.

**Joe Rogan** (1:18)
Yeah. Why did you...
Please explain to people what ʻOumuamua is, why it's so extraordinary, and why you think it's possible that it came from some other intelligent civilization.

**Avi Loeb** (1:29)
Right. So, I'm a scientist, and I basically follow the evidence. Just like Sherlock Holmes, trying to find solutions. It's a detective story. You have some anomalies, some things that don't quite match what you expected, and you're trying to find an explanation. And the thing about Oumuamua is that it was discovered on October 19th, 2017, a little more than three years ago. And it was the very first object that visited our vicinity in the solar system from outside the solar system. It moved too fast to be bound to the sun. Very first object that we have found coming to us from interstellar space, from other places. And at first, astronomers said, oh yeah, it's probably just like the objects we had in our solar system, all the rocks that we have seen before.
We have seen comets and asteroids. So a comet is a rock that is covered with ice, water ice. So when it gets close to the sun, the surface gets warmed up and the ice turns into vapor, gas. And you see this beautiful cometary tail behind it. That's what a comet is. An asteroid is just rock without much ice on it.
Actually, the first person to explain what comets are was at Harvard, the university that I am affiliated with. And the story goes that, I mean, it was Fred Whipple, that he went to Harvard Square and saw all the slush during the winter day, you know, and came up with the idea that it's just icy rock or icy rocks or, you know, rocky ice.
And that's what a comet is. And the comets come to us from the periphery of the solar system. And, you know, astronomers said, okay, other stars may have them as well. And, you know, since they are loosely bound, if they are in the periphery, they can be easily ripped apart from their host star. And some of them will fly in our direction. We will see them. So they said ʻOumuamua is probably a comet.
The only problem is there wasn't any cometary tail. So you look for a duck, but it doesn't look like a duck, you know. So then the question is, what is it? And so people said, okay, it's just a rock without any ice on it.
Then the problem was that it exhibited an extra push away from the sun. And usually you get it from the rocket effect. When you make the cometary tail, it pushes the object in the opposite direction, just like a jet plane. A jet plane works by throwing gas out, and that's pushing you forward. So a comet has an extra push when it evaporates.
But there was no cometary tail, so why did it show an extra push? That was the key question in my mind, at which point I started thinking, maybe it's not a comet and not an asteroid, something else, you know. And the other strange thing about it, it changes its brightness by a factor of 10 or more, and the brightness of the object, the light that we see, is simply reflected sunlight. So just think about it, think about a piece of paper, razor thin piece of paper tumbling in the wind, and changing the area that we can see, the projected area of that piece of paper, by a factor of 10 as we look at it. That's exactly what we inferred from this object, spinning around every eight hours, but changing its brightness by a factor of 10, meaning that the area projected on the sky that we see that reflects sunlight, changed by a factor of 10 So that means it has an extreme geometry, most likely flat, if you try to interpret the light that it reflected over, as it was tumbling around.