HN Theater @HNTheaterMonth

Robin Hanson, who coined the term "Great Filter", presented a theory in 2021 to explain the Fermi Paradox. It's known as the "Grabby Aliens Theory".

This 12 minute video does a good job of explaining the fairly non intuitive reasoning: https://www.youtube.com/watch?v=l3whaviTqqg

As I understand it (it's not an easy theory to wrap your - or at least my - mind around), the reason we don't see any other civilizations is that we're among the first ones.

This seems very unlikely, but is actually not. Because a successful hi tech civilization would likely be inclined to expand ("be grabby") and fill up the galaxy in ~100 million years, as Fermi pointed out. That would mean all habitable planets would then be taken, and no more civilizations would rise up from primordial goo like ours.

That means - and it's a weird mental leap, but I think it's correct - that almost all civilizations arising "naturally" would have the same experience we have: The universe seems weirdly empty.

I guess it also means that the galaxy is ours for the taking!

⬐ PKop

I'm missing something in these videos. Is it that the perception we're early implies an implausible scenario because "grabby" (I would just call them expansionist) civilizations would also be cloaking their signals (he seems to gloss over this point)? I.e. "they're out there" we just can't see them, or is he saying that would be implausible because we should have been invaded by now by these expansionist empires, therefore since we haven't we are early?

You seem to be saying the theory implies we are early when in the first video I got the impression that is statistically implausible.

I guess my main confusion is, if they are grabby, why haven't we been grabbed?

edit: watched the second video further, I think I get it a little better now. We are generally early and/or somehow advanced aliens expand quickly, otherwise we'd see signals because the signals would propagate faster than their expansion, whereas if they expand quickly, they'll invade us before we see signals, and dominate a larger portion of visible universe.

⬐ BurningFrog

My interpretation, which I'm only 90% sure of, is that if we weren't early we'd be dead, since an earlier civilization would have colonized Earth for their own purposes.

So seeing no one else out there is to be expected.

It's a bit like how it's NOT weird that we happened to evolve on a planet that is so extremely favorable to our form of life.

⬐ cletus

That's not that new an idea. Even at 1% of c we could fully colonize the Milky Way in 10 million years, which is a blink of an eye compared to the >4B years the EArth has been here.

The second issue is that planets don't really matter other than being essentially "mass repositories". They're a highly inefficient way of creating living area. I'm speaking of course of Dyson Swarms as a highly likely alternative. I saw "highly likely" because it requires no new physics, no new materials beyond what we already have, is orders of magnitude more efficient (in living space per unit mass terms) and is essentially just an engineering problem (obviously a big one).

If you accept that premise then it's even less likely there are other spacefaring civilizations within our light cone because they would stick out like a sore thumb. Certainly a whole galaxy of these would be detectable by us currently from millions of light years away.

⬐ kabdib

If we're the forerunners, it's our responsibility to leave behind huge and mysterious artifacts containing the secrets of the universe, filled with traps for the unwary.

"Figby, get those doom-chompers synchronized with the shooting flames!"

"Yes sir!"

"And think of something more profound than 'Be nice to other beings and remember to call your mother(s)' for that final secret. Maybe get someone in the art department to help out."

It's not easy being the Elder Race, but someone has to do it.

Everything from 3 blue 1 brown: https://www.youtube.com/c/3blue1brown

Visualization of Quantum Physics (Quantum Mechanics): https://youtu.be/p7bzE1E5PMY

history of the entire world, i guess: https://www.youtube.com/watch?v=xuCn8ux2gbs

TIMELAPSE OF THE FUTURE: A Journey to the End of Time (4K): https://youtu.be/uD4izuDMUQA

Humanity was born way ahead of its time. The reason is grabby aliens. and Grabby aliens: when we'll meet them, how big they are, and other predictions

https://youtu.be/l3whaviTqqg

https://youtu.be/LceY7nhi6j4

Everyday Astronaut videos (he has 90 min documentary on Soviet rocket engine): https://www.youtube.com/channel/UC6uKrU_WqJ1R2HMTY3LIx5Q

Cool Worlds - a lot of 25-35 min very nice astronomy explanations: https://www.youtube.com/c/CoolWorldsLab

'A Universe From Nothing' by Lawrence Krauss: https://www.youtube.com/watch?v=7ImvlS8PLIo

The the unseen ones are mostly the harmless ones. The grabby (basically the "expansionist Dyson sphere builders") are the ones we should be on the lookout for.

https://www.youtube.com/watch?v=l3whaviTqqg

https://www.youtube.com/watch?v=LceY7nhi6j4

https://grabbyaliens.com/

Robin Hanson's model explains the data, answers the Fermi paradox. We don't see aliens because if there were aliens to be seen they would be in our place. (Because the hard-steps model parametrized by habitable zone time-frames limited by the lifecycle of stars gives a distribution of emergence of intelligent life. And if just a few of those start expanding, they'll soon cover enormous volumes, taking away the possibility for later emergence of intelligent life.)