I don't agree that human thought patterns have to be rare, or your other assumptions. The only safe bet in this discussion I think, is, we don't know anything for sure.

> At some point we're either going to murder ourselves or create a Von Neumann machine capable of interstellar flight.

There are many, many possibilities for human futures that are between those two and not do extreme. It is absolutely possible we survive millions of years without interstellar travel or self destruction.

> Since that obviously hasn't happened with alien machines

I also think it is not so obvious that this hasn't happened or isn't happening with alien machines. It certainly could be and we would not know either way. A la 2001: A Space Odyssey, perhaps in fact we are a product of alien machines themselves.

There is a book Accelerando by Charles Stross that talks about why neither case might be true - he shows a scenario where life ultimately transforms its host system into a matrioshka brain. At that point distance from the cloud is reduction in bandwidth to the parts of yourself that exist in that cloud- if the matrioshka brain can simulate billions of planets and leaving it makes you incredibly stupid by your normal standards why do it?

>why do it

Because if you don't, someone who does is going to invade for energy and resources. Therefore, refusing to expand is a slow form of suicide, unless you can be somehow certain there's no entity like that in the potentially accessible space.

At some point growth in any star system is going to be finished - energy extraction near maximum, no free matter left to convert into computronium. After that, only two solutions remain: stagnation (death) or expansion. Assuming no instant communication (not just FTL - instant), the bandwidth argument only means it makes more sense to haul energy and computronium from the rest of the accessible space into one point.

We may very well already see it somewhere far away, thinking it's "natural" rather than a construct. I think under current knowledge the most likely prediction is something resembling a sphere (minimizing distances between points) that utilizes black hole power plants, feeding them matter from stars and nebulae.

From the outside, it would look like a giant void with nothing in the center. Maybe there's something like that in the center of the Boötes void?

> Because if you don't, someone who does is going to invade for energy and resources. Therefore, refusing to expand is a slow form of suicide, unless you can be somehow certain there's no entity like that in the potentially accessible space.

I've heard that described as "where are the supernova defense systems?" Of course, I'm not aware of any explanations for why it's physically impossible to have a relatively small system sufficiently "hardened" to survive a supernova, or perhaps a way to defend oneself (including hiding) that doesn't require stasis.

Accelerando is a great book even if his writing style is a little dry. The mass of one planet being able to simulate billions of planets is only possible if the simulation is rather poor. You can't create a perfect simulation like that any more than you can perfectly simulate seven atoms using three atoms. Computation is never going to be more efficient than physics.

why do it?

Everyone doesn't have to do it. Just one person out of billions does. Think of the strange and perverse collection of behaviors we observe in a population of a few hundred million people online and speaking English. Expand that to billions of hyperintelligent minds and somebody is going to want to colonize the universe.

I agree about the writing being dry. Honestly I couldn't finish it, it felt more like a series of interesting future wikipedia articles than a novel. The problem is sometimes those interesting wikipedia articles will be in between about 50 pages of sci-legal-fiction describing a legal ecosystem where sentient corporations are conducting some kind of mysterious magic future economics / ecology that is never actually described.

But anyway back to the discussion:

>The mass of one planet being able to simulate billions of planets is only possible if the simulation is rather poor

The mass of one solar system! And you don't need to simulate the system to a planck length. In fact the book specifically addresses that scenario - different simulations have different planck lengths and planck times, depending on the needs of the users of that simulation. For most users (certainly your average modern baseline human) that length might be on the orders of fractions of a mm, and some users might not require a physically meaningful interface at all!

>Everyone doesn't have to do it. Just one person out of billions does.

That's assuming that the culture doesn't have significant bans on von-neumann style self-replicating machines. If they allowed such devices of course you'd expect an expanding light cone of computronium around every significantly advanced culture but any sane long-lived culture would recognize that such machines are just about the only existential threat that a culture with those capabilities would face. That might significantly limit the 'explorer' class to those entities willing to do the equivalent of taking an ice pick to the frontal cortex in modern humans in order to undertake a multi-multi-millennia solitary journey into the void. Some fraction of those trips would fail, and the successes would take a non-trivial amount of time to launch another. Maybe those growth rates are smaller than we would suppose and the universe has only had stars capable of producing the elements of life for a little while on a universal scale, maybe those light cones just haven't reached this corner of space yet.

> At a bare minimum, human thought patterns have to be rare.

Definitely. In fact, I think they are almost certainly unique in our entire local galaxy cluster, and we will never find anything even close.

We could very well find something interesting, enlightening, sophisticated or using what we might be able to squint and call technology, but I suspect we will never find an alien civilization intentionally broadcasting for example the fibonacci sequence or prime numbers so that we can learn to exchange culture and communicate ideas.

> At a bare minimum, human thought patterns have to be rare.

I'm not so sure. We can't even be sure if cetaceans, in particular orcas, have thought patterns similar to ours. Of course, they lack the physicality and environment to develop written history and knowledge and also technology, but we currently have no way of knowing what their thoughts are.

Agreed. How then could we expect to exchange views with an alien species, when we cannot do the same even with Earth species? We imagine it would somehow be easier if only the alien species were "intelligent", but then our expectation arguably defines intelligence in No True Scotsman terms, essentially an intelligent species is one with which we could communicate.

Most would argue against a species being intelligent if we could not communicate with it. "These are just automatic processes, like sophisticated software"