Is Interstellar Colonization the Great Filter?

[Rynn]

I certainly think it's a good candidate. I don't think it's a complete show stopper but something I've often thought about is how the technologies you need to make it feasible have much better applications in the home system. As you say if you're building a generation ship you need to design an self-sustaining economy that can last thousands of years in isolation with just the resources it has. That's hard enough but almost always forgotten in science fiction is the social side; no human society has lasted millenia without conflict and conflict in a small closed system would easily turn fatal. Thus your social science needs to be so sophisticated that you can design a socioeconomic system with a life expectancy (i.e. how long until it experiences a significant violent conflict or drifts towards a system more likely to have one) of millenia. If you can do that you can probably make some very sophisticated social institutions at home, ones that you can monitor and adjust in real time. Thus one of the basic arguments for interstellar colonisation, the exodus of groups that seek political independence, is significantly mitigated.

If you start adding technologies for easier kinds of interstellar colonisation like robotics, automation, molecular manufacturing etc you enable your civilisation to start building huge power harvesting installations. Megastructures like partial Dyson swarms to harvest many exawatts from the system star to be used for projects such as boosting colony vessels to a high fraction of C. But that technology also has a much better use at home. Why dedicate a significant fraction of a Dyson swarm's power output for a significant time just to boost a few thousand people to another system when all of those resources can be used to build habitat space in the swarm? A habitable Dyson swarm would have more livable space than if every star in the galaxy had a score of perfectly habitable planets, all within light minutes of each other.

Another technology that seems to tip the scales towards interstellar colonisation at first is uploading/AI. If you are a civilisation of either you don't need to boost a generation ship, you can boost a neumann probe several orders of magnitude smaller in mass and then email yourself to the facility its descendents build upon arrival. But just like the others there's another use of this technology that tips the scale the other way more. If you run on a processor you can increase your clock rate arbitrarily depending on the capabilities of your systems and code. You don't have to do this but even in very peaceful egalitarian societies it is useful for anyone engaging in serious projects (scientific, artistic, political etc) meaning that it's likely a good fraction of people's time is spent at higher clock rates. A side effect of this is to make the universe grow in size as the subjective time it takes for objects or even light to cross distances increases. That self replicating probe despatched to a system 20ly away at 0.5C might actually take tens of thousands of years to arrive measured by your internal clock. And if you email yourself to it what do you get? Separated from your home civilisation (which could consist of more environments and people than an entire local cluster with civilisations around every star) for tens-hundreds of thousands of years for some different astronomical bodies.

Either dyson swarm would also naturally make building a hypertelescope array total pocket change. Boosting a few million/billion units to orbits 50AU away (making a 100AU wide array) would be very energetically cheap compared to an interstellar ark launch and would be able to resolve objects 1 meter in size over 2500 light years away. You could spot large buildings with it on planets on the other side of the galaxy. Combined with virtual technology the entire galaxy could be recreated to a high degree of accuracy inside a virtual environment with scientific models so accurate that there isn't any significant difference. The only exception to this would be if life was spotted, as there is only so much you could derive about the biochemistry from optical analysis.

None of these make interstellar colonisation impossible, I don't think any realistic GF does, but to my mind they certainly make it far less certain that it would happen. For every civilisation that manages to get to the above technology level the vast majority may never leave their system, instead exploring the universe through their data/models and enjoying a cultural richness beyond any fictional galactic empire.