Макс Тегмарк - Life 3.0 - Being Human in the Age of Artificial Intelligence

The possibility of superintelligence completely transforms this picture, making it much more promising for those with intergalactic wanderlust. Removing the need to transport bulky human life-support systems and adding AI-invented technology, intergalactic settlement suddenly appears rather straightforward. Forward’s laser sailing becomes much cheaper when the spacecraft need merely be large enough to contain a “seed probe”: a robot capable of landing on an asteroid or planet in the target solar system and building up a new civilization from scratch. It doesn’t even have to carry the instructions with it: all it has to do is build a receiving antenna large enough to pick up more detailed blueprints and instructions transmitted from its mother civilization at the speed of light. Once done, it uses its newly constructed lasers to send out new seed probes to continue settling the galaxy one solar system at a time. Even the vast dark expanses of space between galaxies tend to contain a significant number of intergalactic stars (rejects once ejected from their home galaxies) that can be used as way stations, thus enabling an island-hopping strategy for intergalactic laser sailing.

Once another solar system or galaxy has been settled by superintelligent AI, bringing humans there is easy—if humans have succeeded in making the AI have this goal. All the necessary information about humans can be transmitted at the speed of light, after which the AI can assemble quarks and electrons into the desired humans. This could be done either rather low-tech by simply transmitting the two gigabytes of information needed to specify a person’s DNA and then incubating a baby to be raised by the AI, or the AI could nanoassemble quarks and electrons into full-grown people who would have all the memories scanned from their originals back on Earth.

This means that if there’s an intelligence explosion, the key question isn’t if intergalactic settlement is possible, but simply how fast it can proceed. Since all the ideas we’ve explored above come from humans, they should be viewed as merely lower limits on how fast life can expand; ambitious superintelligent life can probably do a lot better, and it will have a strong incentive to push the limits, since in the race against time and dark energy, every 1% increase in average settlement speed translates into 3% more galaxies colonized.

For example, if it takes 20 years to travel 10 light-years to the next star system with a laser-sail system, and then another 10 years to settle it and build new lasers and seed probes there, the settled region of space will be a sphere growing in all directions at a third of the speed of light on average. In a beautiful and thorough analysis of cosmically expanding civilizations in 2014, the American physicist Jay Olson considered a high-tech alternative to the island-hopping approach, involving two separate types of probes: seed probes and expanders .7 The seed probes would slow down, land and seed their destination with life. The expanders, on the other hand, would never stop: they’d scoop up matter in flight, perhaps using some improved variant of the ramjet technology, and use this matter both as fuel and as raw material out of which they’d build expanders and copies of themselves. This self-reproducing fleet of expanders would keep gently accelerating to always maintain a constant speed (say half the speed of light) relative to nearby galaxies, and reproduce often enough that the fleet formed an expanding spherical shell with a constant number of expanders per shell area.

Last but not least, there’s the sneaky Hail Mary approach to expanding even faster than any of the above methods will permit: using Hans Moravec’s “cosmic spam” scam from chapter 4. By broadcasting a message that tricks naive freshly evolved civilizations into building a superintelligent machine that hijacks them, a civilization can expand essentially at the speed of light, the speed at which their seductive siren song spreads through the cosmos. Since this may be the only way for advanced civilizations to reach most of the galaxies within their future light cone and they have little incentive not to try it, we should be highly suspicious of any transmissions from extraterrestrials! In Carl Sagan’s book Contact, we Earthlings used blueprints from aliens to build a machine we didn’t understand—I don’t recommend doing this…

In summary, most scientists and sci-fi authors considering cosmic settlement have in my opinion been overly pessimistic in ignoring the possibility of superintelligence: by limiting attention to human travelers, they’ve overestimated the difficulty of intergalactic travel, and by limiting attention to technology invented by humans, they’ve overestimated the time needed to approach the physical limits of what’s possible.

Staying Connected via Cosmic Engineering

If dark energy continues to accelerate distant galaxies away from one another, as the latest experimental data suggests, then this will pose a major nuisance to the future of life. It means that even if a future civilization manages to settle a million galaxies, dark energy will over the course of tens of billions of years fragment this cosmic empire into thousands of different regions unable to communicate with one another. If future life does nothing to prevent this fragmentation, then the largest remaining bastions of life will be clusters containing about a thousand galaxies, whose combined gravity is strong enough to overpower the dark energy trying to separate them.

If a superintelligent civilization wants to stay connected, this would give it a strong incentive to do large-scale cosmic engineering. How much matter will it have time to move into its largest supercluster before dark energy puts it forever out of reach? One method for moving a star large distances is to nudge a third star into a binary system where two stars are stably orbiting each other. Just as with romantic relationships, the introduction of a third partner can destabilize things and lead to one of the three being violently ejected—in the stellar case, at great speed. If some of the three partners are black holes, such a volatile threesome can be used to fling mass fast enough to fly far outside the host galaxy. Unfortunately, this three-body technique, applied either to stars, black holes or galaxies, doesn’t appear able to move more than a tiny fraction of a civilization’s mass the large distances required to outsmart dark energy.

But this obviously doesn’t mean that superintelligent life can’t come up with better methods, say converting much of the mass in outlying galaxies into spacecraft that can travel to the home cluster. If a sphalerizer can be built, perhaps it can even be used to convert the matter into energy that can be beamed into the home cluster as light, where it can be reconfigured back into matter or used as a power source.

The ultimate luck will be if it turns out to be possible to build stable traversable wormholes, enabling near-instantaneous communication and travel between the two ends of the wormhole no matter how far apart they are. A wormhole is a shortcut through spacetime that lets you travel from A to B without going through the intervening space. Although stable wormholes are allowed by Einstein’s theory of general relativity and have appeared in movies such as Contact and Interstellar, they require the existence of a strange hypothetical kind of matter with negative density, whose existence may hinge on poorly understood quantum gravity effects. In other words, useful wormholes may well turn out to be impossible, but if not, superintelligent life has huge incentives to build them. Not only would wormholes revolutionize rapid communication within individual galaxies, but by linking outlying galaxies to the central cluster early on, wormholes would allow the entire dominion of future life to remain connected for the long haul, completely thwarting dark energy’s attempts to censor communication. Once two galaxies are connected by a stable wormhole, they’ll remain connected no matter how far apart they drift.