It makes me wonder about what it would take to actually create one.

You’d need self-replicating machines to build it, naturally. You’d need some ability for them to mine from asteroids and process the materials right there on the spot. And they’d need to be able to build both the processor “swarmlets” (probably some stamped-out solar/engine/CPU package) and more builders, so that the growth can be exponential. Oh, and the ability to turn solar energy into thrust somehow using only fuel you can get from the mined asteroids. Maybe a prerequisite is finding a solar system that has a huge and extremely uranium-rich asteroid belt.

You would need a CPU design that can be built using the kind of fidelity that a self-replicating machine in space under constant solar radiation can achieve. But if you can get the scale high enough, maybe you can just brute force it and make machines on the computational scale of a Pentium 3, but there’s 10^40 of them so who cares. Maybe there’s a novel way of designing a durable computing machine out of hydrocarbons we have yet to discover.

The machines would have to self replicate, and you’d need to store the instructions somewhere hardened. And that can be built out of materials commonly found in asteroids. Maybe hydrocarbons. Hell, may as well use RNA. These things need to be as good as humans at building stuff, so really this is just creating artificial “life” that self has DNA and is made of cells that build proteins needed to create the machine. Maybe they reproduce by spreading as little DNA seeds that can attach to an asteroid with the right chemistry, and we just spew them into the cosmos at a candidate star and hope the process gets kickstarted. Hell, we could make it spew its own DNA at the next stars over as soon as it’s done. We’d have a whole galaxy computing for us, all we’d need is the right DNA instructions, the right capsule for them, and a way to launch them.

Maybe another civilization has already done this…