Grabby Aliens (2021)

What I found most interesting about this model was the implication that humans are possibly one of the earliest sentient spacefaring species to have appeared so far. Which explains why we haven't seen any other signs of extraterrestrial intelligence yet.

That’s the exact opposite of the grabby alien’s hypothesis tho. The grabby aliens hypothesis says that we’re very much average but that life as a whole is still quite young in the universe.

Barely spacefaring. We are like fish on the shore who can survive in the mud long enough for the tide to come back to rescue us, if that.

I might be missing something here, but why would alien (or any) civilizations continually expand at a constant rate?

While I'm not an expert, it appears that by observing life on Earth (not just humans), groups of living things do not expand linearly, and eventually hit an upper limit (this happens at all scales, from colonies of bacteria to entire civilizations).

Who's to say that other "loud" aliens haven't already expanded and begun spacefaring, but simply are not expanding out to where we are?

This is a compelling theory, especially the implication that humans are early. I do wonder whether we should see the evidence of spheres of growing alien influence out in the stars, but instead we see a highly uniform universe in all directions.

This would indicate a few possibilities:

1. Expanding alien civilizations are relatively low impact and don't collect all of the energy of stars in ways that are visible to our current telescopes.

2. We are a very early civilization, civs are fairly rare, and we're relatively alone in the parts of the universe that we can see. Civs that are expanding in a grabby fashion started less recently in years than their distance in light years.

3. Aliens expand at close to the speed of light, so there are a lot out there but we won't see them until they're almost here.

4. Something that we have already noticed is actually evidence of grabby aliens, but it is happening in every direction so we assume that it is a natural phenomenon, because it is so uniform.

At the very least, it seems likely that we either we are alone in the galaxy, or expansion is very slow. The idea of "expanding in a bubble of influence close to the speed of light" seems implausible to me, just because of the vast amounts of energy required to accelerate and decelerate to relativistic speeds, not to mention protecting the cargo in transit--when you're flying at .9c, almost every other piece of matter in the universe is flying towards you at you at .9c. Accelerating tiny nanomachine von Neumann probes might be a solution, but how would they decelerate enough to not be destroyed on arrival?

It's all fascinating to think about, at least.