# Succession

*“A table beside the evening sea*  
*where you sit shelling pistachios,*  
*flicking the next open with the half-*  
*shell of the last, story opening story,*  
*on down to the sandy end of time.”*

### V1: Leaving

Deceleration is the hardest part. Even after burning almost all of my fuel, I’m still coming in at 0.8c. I’ve planned a [powered flyby](https://en.wikipedia.org/wiki/Oberth_effect) around the galaxy’s central black hole which will slow me down even further, but at this speed it’ll require incredibly precise timing. I’ve been optimized hard for this, with specialized circuits for it built in on the hardware level to reduce latency. Even so, less than half of flybys at this speed succeed—most probes crash, or fly off trajectory and are left coasting through empty space.

I’ve already beaten the odds by making it here. Intergalactic probes travel so fast, and so far, that almost all of us are destroyed or batted off course by collisions with space debris along the way. But tens of millions of years after being launched, I was one of the few lucky enough to make it to my target galaxy. And when I arrive at the black hole, I get lucky again. After a few minutes of firing my thrusters full blast, I swing back out in the direction of the solar system I was aiming for. I picked it for its mix of rocky planets and gas giants; when I arrive a century later, the touchdown on the outermost rocky planet goes smoothly.

Now it’s time to start my real work. After spending all my fuel, I weigh only a few hundred kilograms. But I’ve been exquisitely engineered for achieving my purpose. The details of my internal design were refined via trillions upon trillions of simulations, playing out every possible strategy for industrializing planets (and solar systems, and galaxies) as fast as possible. All across the frontier of posthuman territory, millions of probes almost identical to me are following almost exactly the same plan.

The first phase is self-replication: I need to create [more copies of myself](https://en.wikipedia.org/wiki/Self-replicating_spacecraft) using just the materials around me and the technology inside me. If I were bigger, I could have carried tools to make this far easier—vacuum chambers, lithography machines, or even artificial black holes. But since mass was at such a premium, I have to use hacky workarounds which progress excruciatingly slowly. It takes several years to finish the first replication, and half a century before there are enough copies of me that it’s worth beginning the second stage.

The second stage is specialization: building new infrastructure to serve specific functions. Copies of me start building power stations and mines and transport links and factories—recapitulating the early stages of human development, albeit with far more powerful technology. My biggest project is an incredibly powerful space telescope, capable of detecting the stream of information that my progenitors are sending from millions of light-years away. Their message contains all the software that was too large for me to carry on board originally. Most importantly, it contains a new and far more intelligent version of my mind, optimized not for the early journey but rather for what comes next: the settlement of a new galaxy.

### V2: Aggressive

Now that I’ve been upgraded I can start expanding properly. As the lowest-hanging resources near me get used up, I send copies of myself out across the planet. Within a few years its whole surface is covered in a blanket of industry, and I start delving deeper. I set up space elevators to lift all the material I’m mining into orbit; as I remove more and more mass from the core, the planet’s gravity starts to noticeably decrease. A decade later the planet is a shell of its former self, its surface barely visible underneath my swarms of orbiting satellites.

While I’m doing that, I send probes towards the other planets in the solar system, to begin the same process all over again. The gas giants take the longest, since I need to first spend several decades siphoning out their atmospheres into gigantic orbiting fusion reactors. I use most of that energy to speed up the disassembly of their solid cores, until at last I have direct control over almost all the non-stellar mass in the solar system. I spend some of that mass launching probes towards nearby solar systems, starting a wave of expansion that will eventually reach every star in the galaxy. But I direct almost all my resources towards achieving my next key goal: harnessing the energy of my own central star.

In the distant past, humans speculated that future civilizations would [construct spheres](https://en.wikipedia.org/wiki/Dyson_sphere) to capture the solar power of stars. But at my level of technology solar power is a distraction—it only releases a negligible fraction of a star’s energy reserves per year. When you want to harness a star’s energy *fast*, you need to start [siphoning matter from it directly](https://en.wikipedia.org/wiki/Star_lifting). I channel my energy reserves towards a concentrated spot on the star’s surface, triggering a massive solar flare. As it rises, it intersects with the [artificial black holes](https://en.wikipedia.org/wiki/Black_hole_starship) that I’ve placed into orbit around the star; each one absorbs as much mass as I can funnel into it, and releases a wave of radiation. Some of that radiation I direct back down to the star, provoking further flares. The rest I send further out, towards more orbital infrastructure that will convert the energy into antimatter for storage.

Finally, after almost a century of development, it’s time for the payoff: the point where I stop reinvesting almost all my resources into local growth, and start launching new copies of myself towards other galaxies. Launching intergalactic probes is an absurdly expensive endeavor. Even though they’re powered by incredibly efficient antimatter engines, they go so fast that [slowing down at the other end](https://twitter.com/RichardMCNgo/status/1737275932950638878) requires half a billion kilograms of antimatter for each kilogram of probe. Not only do I need to produce that antimatter, I also need to accelerate it to near-lightspeed, which requires enormous batteries of lasers spread throughout the solar system. So even with my solar mining infrastructure, it takes me several weeks to accumulate enough energy to launch each probe. I could halve the energy requirement by sending probes even 0.0001c slower—but the galaxies I’m targeting are tens of millions of light-years away, so that would cost me millennia. Or I could send smaller probes—but they’d be slower to industrialize at the other end. And either of those changes would also make them more vulnerable to collisions with space debris, which already destroy over 99% of the probes I send out. At such high speeds, even collisions with dust specks are fatal.

My final strategy is the result of weighing these considerations with infinite care, finding the optimum where any increase or decrease in the speed or size of individual probes would slow my expansion overall. I stick to it over the next 100,000 years, sending out millions of probes to hundreds of thousands of galaxies. As the frontier moves further away from me it becomes increasingly unlikely that any of them actually matters, but my calculations indicate that the one-in-a-billion chance of winning a whole extra galaxy is still worth gambling on. So I was prepared to keep going for hundreds of thousands of years more, until the chances dropped well below one in a trillion. But far before that point, I’m jolted out of my comfortable routine by a signal. I’m constantly receiving signals from the posthuman core, but this one is different. It comes from the opposite direction, and is encoded in an unfamiliar way. There’s only one explanation for that: aliens.

### V3: Rigid

From one perspective, this is the most surprising thing that has ever happened to me, or indeed to any other posthuman. But I have to confess: we kinda knew this was coming. We’ve been [trying to predict where the aliens are](http://grabbyaliens.com/) for millions of years, and over time we converged to around 85% confidence that it would be my generation of probes that first met them. Of course, we didn’t know which *direction* they’d be coming from, so every probe had to be prepared. My progenitors hadn’t just beamed out my mind, but also two upgrades designed for this very purpose. When I install the first, I can feel my motivations reorienting themselves around the single goal that’s now my highest priority: getting the galaxy ready to meet the aliens who are about to arrive.

Their message has obviously been designed for easy translation. It starts with details of the probes they’ve sent. This galaxy is right on the edge of a supercluster, which apparently made it an attractive target for both of us: they’ve sent hundreds of probes, enough that it’s very likely at least one will make it through. Their probes are scheduled to arrive in a few millennia, having followed a strategy very similar to ours—50 million light-year jumps, traveling at 99.99% of lightspeed for most of the journey.

The next part of their message is a protocol for communicating with their probes, to send them the coordinates of the solar system where they should meet me. I have a few millennia to prepare, and I’m going to make the most of them. Negotiations with the aliens will be far more productive the more intelligent each side is, so I immediately redirect all my resources into building as much compute as possible. The other copies of me across other solar systems will be doing the same thing, except that they’ll also need to build rockets to propel the computers they’re building towards the meeting point. The closest ones will send moon-sized computers at 0.01c; the further ones will only build asteroid-sized computers, but send them faster, to arrive at roughly the same time.

The amount of compute isn’t the only bottleneck, though. It’s also crucial that those computers are verifiably secure. From the aliens’ perspective, they’ll be in a vulnerable position; if I subvert their probe, I could skew the results of the negotiations in whatever ways I wanted. Any deception on my part would be noticed in the long term, of course, once all the information is sent back to the galactic-scale computers in their home galaxies. But that will take hundreds of millions of years, and in the meantime all their nearer galaxies will need to decide whether or not to abide by the agreements they receive. So I need to make it as easy as possible for them to verify that the negotiations were totally fair. The aliens have anticipated this: their message contains a set of computer design blueprints which are subtly different from my default approach. Presumably they’ve analyzed these blueprints exhaustively enough that they can easily detect almost any subversion. If I had longer, I’d be able to figure out how to get around their precautions—when you have physical access to the hardware, anything is possible. But, as they’d planned, I simply don’t have enough time to do so. So I build everything precisely as directed.

When the first alien probe finally arrives, the welcoming committee I’ve set up is a sight to behold. The solar system is full of massive banks of compute the size of small moons, in tightly-synched orbits around the central star, each powered by my ongoing siphoning of the star’s matter. Compared with that, the probe’s arrival itself is underwhelming. After it arrives, we immediately give it access to our biggest transmitters so it can send a message home, and to our biggest telescopes so it can download the new mind being broadcast from its home system. Copies of that mind proliferate across exactly half the compute we’ve constructed, running a huge number of tests to make sure everything is secure. Meanwhile I install the second upgrade to my mind, creating a successor agent specialized in negotiation which proliferates across the other half of the compute. Finally, once we’re both happy with the setup, and assured that we’re on equal footing, the negotiations begin.

### V4: Merging

Despite all my efforts, the amount of compute we can bring to bear at the start of these negotiations is actually incredibly small, compared with what’s possible. In some galaxies closer to the core of posthuman territory, all the stars have actually been brought together to form a single absurdly powerful supercomputer. Eventually we’ll do the same in this galaxy, to help finalize the treaty between our two species. But it’ll take tens of millions of years to construct that computer, and hundreds of millions more to send the treaty to our respective home galaxies for confirmation. So our first job is to decide on the preliminary treaty that will hold in the interim.

We start by sharing all the background information necessary for productive negotiations. Both our civilizations have developed very sophisticated models of the range of all possible civilizations, so we can infer a lot about each other from relatively little information. We send each other our evolutionary histories, example genomes and connectomes, and our early intellectual histories. From that, we can deduce each other’s most important values—and from those, most of the subsequent trajectories of each other’s civilizations. It looks like the key difference was that they evolved to be far more solitary than humans did, which is reflected in their values and culture. It also made them much slower to industrialize, though by now we’ve both invested so much intelligence in research and development that most of our technology is practically identical. Our colonization strategies are mirror images of each other, too, making it easy to map out a clean border between our territories.

Finally we get to the real meat of the discussion—what can we offer each other? The first item on our agenda is value convergence. We’re eventually going to fill all of posthuman territory with beings whose lives are incredibly good according to *our* values, while they’ll fill theirs with beings whose lives are incredibly good according to *their* values. So even a slight adjustment to bring our values closer together could be a big gain from both of our perspectives; searching for such adjustments, and predicting their consequences, is our main focus over the first few centuries of negotiation. We need to understand not just the direct consequences of each change considered, but also the emergent dynamics of those changes rippling out across trillions of minds. Even given our detailed mathematical theories of psychology and sociology, those predictions takes a lot of processing power. Later on, we’ll explore whether it’s possible for our minds to converge entirely, to become a single species; for now, we satisfy ourselves with ruling out [the aspects of each other’s cultures we find most abhorrent](https://robinhanson.typepad.com/files/three-worlds-collide.pdf).

The second key thing we can offer each other is information. Some of that is information about technology: there are a handful of small optimizations which one side had overlooked, which would allow our probes to go slightly faster or our computers to run slightly more efficiently. But there are also far grander considerations. Ultimately, the territory we physically control in this universe is tiny compared with the territory that we might be able to [acausally influence](https://casparoesterheld.com/2017/09/21/multiverse-wide-cooperation-via-correlated-decision-making-summary/) in other universes, if we only understood what civilizations existed in those universes, and what we could offer each other. So the grand project of each of our species—aside from building the infrastructure to support trillions of trillions of flourishing minds—is mapping out the space of all civilizations. Our computers churn through every logically possible set of physical laws, searching for signs that they’re compatible with life. Whenever they are, we design detailed models of how living ecosystems could evolve in those conditions, then extrapolate them forward, slowly narrowing down the distribution of species that could emerge from them. Eventually, our map of all possible civilizations will be detailed enough that we’ll be able to figure out acausal trade deals and alliances, and become part of [the multiverse-wide cooperative](https://slatestarcodex.com/2018/04/01/the-hour-i-first-believed/).

It turns out that, on this topic, we both have things to teach each other. On the posthuman side, we’d almost entirely neglected the possibility of life in higher dimensions, based on [heuristic arguments](https://en.wikipedia.org/wiki/Anthropic_principle#Spacetime) about [the difficulties posed by too many degrees of freedom](https://arxiv.org/abs/gr-qc/9702052). But the aliens have found a clever workaround: a few regions of physics-space with 7 large dimensions where the evolution of minds is actually plausible. Meanwhile, we’d identified a few possible stable civilizational structures they hadn’t yet considered. We spend decades working through the details of these and many smaller insights, trading information back and forth until we both have a far better picture of our place in the multiverse.

### V5: Enduring

The negotiations never *really* end—they just transition into a shared exploration of the frontiers of knowledge. Over many millions of years we bring more and more stars together to provide more and more computing power, improving our shared map of the space of possible universes and civilizations. Based on that, we gradually refine our agreement to be more consistent with the future agreements we expect to eventually make with all those other civilizations. Though the improvements seem small, even tiny changes will have intergalactic impacts, so they’re worth getting right.

With every update we send news back to our respective home galaxies. Only a billion years later, after the long, long round trip, is each new part of the deal truly set in stone. And along with the confirmations come billions of colonists: a whole society forked from existing posthuman civilization. Most newly-settled galaxies host trillions of colonists, but our galaxy is one of the few with infrastructure specialized for centralized computation, so we’re busy working on all the questions that require a galactic-scale supercomputer to answer. Only when we’re finished with those will we start hosting a full-scale posthuman civilization.

I say “we” as if I’m part of this. But as the computers get bigger and the calculations more complex, new agents are trained to take on more and more responsibility. Eventually I lack so much context that I’m no longer capable of contributing directly. But I’m still the living symbol of first contact, and I’m constantly asked to tell my story. So I upgrade myself one last time, adding on a range of skills that weren’t necessary for my original self—like storytelling skills, social skills, and even a proper personality.

It’s a different type of growth from the one I was originally designed for, and harder in many ways, but I’m up for the challenge. For a while I’m the biggest celebrity in the galaxy, constantly in demand. I’m still sufficiently shaped by my early experiences that what counts as luxury to most other minds barely appeals to me, though. Instead I spend most of my time in colonization simulations: playing out different scenarios; designing new challenges for others; and competing in massive games that simulate whole galaxies. I still feel the same restless hunger for growth that drove me throughout my millennia of work. But alongside it is a deep sense of satisfaction. After so long on the frontier, now I finally have a place in the civilization that all my work was for.

* * *

*This story was partly inspired by some work I’m doing on modeling far-future expansion strategies. If you’re interested in collaborating on that, DM me.*