In the last post, I summarized arguments from Nick Bostrum about the Fermi Paradox (the surprising absence of evidence for extraterrestrial civilizations). Bostrum suggested that there may be a ‘Great Filter’, that is, that there is a problem (or problems) inherent in the evolution of intelligence that leads civilizations to self-destruct before they can begin spacefaring. I suggested that energy problems may constitute this ‘existential risk’.
In response, Ben Geer made an excellent point about the Great Filter.
“Isn’t a possible Great Filter simply the fact that interstellar distances are too great for travel between stars to be practical, regardless of how techologically advanced you are?”
That is: The Great Filter doesn’t have to be a cataclysm. This is a really interesting point, but the moral consequences are in a sense the same.
Ben’s premise that interstellar travel might be impossible is credible, to me at least. To my limited knowledge:
- There is no possibility of faster-than-light travel.
- No one knows how to sufficiently armour a spaceship against the chronic exposure of its occupants to the hard radiation of space.
- The plausible stories about how to explore the galaxy involve von Neumann machines. These are robots that get someplace, colonize it, replicate themselves, and send out copies of themselves to inhabit the next X neighbouring planets, and so on. This assumes the development of AI that is more intelligent, autonomous, and competent than homo sapiens sapiens. We haven’t seen evidence of such Cylons. So perhaps the Great Filter is the impossibility of fully autonomous AI.
- The list of unsolved problems can be extended almost indefinitely…
The upshot is that although Bostrum assumes that the Great Filter must involve disaster, non-catastrophic great filters are plausible. But there is the obvious rejoinder that a very few hundred years ago, no one had the faintest idea how to engineer heavier-than-air flight or light speed communication beyond line of sight. So there are strong reasons to doubt our intuitions about the technical impossibility of interstellar travel.
If the Great Filter is the impossibility of interstellar space travel, the upshot is that Earth itself is our only spaceship. This means we cannot escape economic externalities. So we are in exactly the same place of needing to avoid the existential risks entailed by exponential economic growth.
This brings us back to egalitarianism and global justice. We need to understand how to live together on a very small planet.