Joe Rogan Experience #1596 - Avi Loeb

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The Joe Rogan Experience.

Train by day, Joe Rogan podcast by night. All day. (rock music) Hello, Avi.

Thanks for having me.

My pleasure. Uh, I, um, I'm very good friends with your friend, Lex Fridman.

Mm-hmm.

And, uh, he highly recommends you as well.

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.

(laughs)

(laughs)

Yeah, he reads accounts.

(laughs)

He read... And he, he says he doesn't, but then he does. He reads, like comments and stuff, and then he gets mad at things people say. It's kinda funny.

Yeah. You see, I save the time. I don't even read what other people say.

Good for you.

And I don't care how many likes I have. That's the other thing.

That's wonderful. That's a freedom.

Yeah, exactly.

It's a underrated freedom.

Yeah.

Uh, you came on my radar when, uh, you were discussing, uh, a, a mu, a Oumuamua. Is that how you say it?

Yes, that's the right thing.

A Oumuamua, 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.

Right.

Yeah. Why did you... d- why... Te- please explain to people what a Oumuamua is, why it's so extraordinary, and why you think it's possible that it came from some other intelligent civilization.

Right. So, I'm a scientist and, uh, I basically follow the evidence, just like Sherlock Holmes-

(laughs)

... 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, uh, the thing about Oumuamua is that it was discovered on, uh, October 19th, 2017, um, a little more than three years ago. And, um, 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, uh, 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." Uh, we have seen comets and asteroids. So a, a, 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, um, gas. And you see this beautiful cometary tail, uh, behind it. That's what a comet is. An asteroid is just rock without much ice on it. Actually, the first person to explain, uh, what comets are, uh, was at Harvard, the university that I, uh, am affiliated with. And the, the story goes that... I mean, it was Fred Whipple that he went to Harvard Square and saw all the slush, uh, during the winter day, you know, and came up with the idea that it's just icy rock or icy, icy rocks or, you know, rocky ice. Uh, and, um, that's what a comet is. And, um, 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, since they're 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 Oumuamua 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 that when, when you make the cometary tail, uh, 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. Uh, 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, it changes its, uh, 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, uh, think about a piece of paper, razor thin piece of paper tumbling in the wind and changing the area that we can see, uh, 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, uh, over... as it was tumbling around. And so a flat object about the size of a football field that has an extra push, if it were a comet, it needed to lose about a tenth of its, uh, weight. So a lot of evaporation. You can't just say, "Oh, it's a little bit of evaporation and, uh, therefore that's why we don't see it." It should have lost a tenth of its weight, you know? If we go on a diet and lose a tenth of our weight, that's, that's a big chunk of, of, of mass, right? So this object didn't lose that because we didn't see it. And the Spitzer Space Telescope looked very deeply behind it to see if there are any traces of dust or, or gas. Didn't see anything. So then...... you know, just like Sherlock Holmes, I was trying to think, together with, um, a- a post-doc of mine, uh, Shmuel Bialy, what could explain it. And the only thing that came to mind is reflecting sunlight. So, um, the object itself is being pushed by the sunlight reflecting off its surface. And, you know, um, that would agree with everything we know about the object, but in order for it to work, the object needs to be very thin, like a sail. You know, the sail on a boat?