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Evolutionary Game Theory of Interstellar Colonization

Burning the Cosmic Commons. Evolutionary Game Theory of Interstellar Colonization . Robin Hanson Dept. of Economics George Mason University. Our Future?. Alien Past?. The Big Picture. Modeling Galactic Colonization. Hart 75: calc, <1MY, if s=.1c, 20Y wait

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Evolutionary Game Theory of Interstellar Colonization

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  1. Burning the Cosmic Commons Evolutionary Game Theory of Interstellar Colonization Robin Hanson Dept. of Economics George Mason University

  2. Our Future? Alien Past? The Big Picture

  3. Modeling Galactic Colonization • Hart 75: calc, <1MY, if s=.1c, 20Y wait • Jones 76: sim, wave v > 10s, .1c => <5MY • Newman & Sagan 81: diff. eqn., given ZPG, 10-8/yr emigration rate, takes 800MY. • Bainbridge 84: sim of 1000 stars, let prob colonize drift, found selection effect. • Fogg 87: sim, .7– 80MY if v = .1-.0001c • Landis 98: sim, percolate leaves some voids

  4. The Universe Looks Dead! • No visits now, artifacts here • No Arecibo’s talk to us at GHz [1000 stars] • No starship exhaust? • < 1% nuke waste dumped into stars [? stars] • < 1% starlight taken, resent at IR [50 stars] • Stars most of mass, yet not disassembled. • Astronomer’s success with “dead” models.

  5. Fermi: “Where Is Everybody?” • We are the first for many MLY (blast killed all?) • Fast interstellar travel is impossible. • All die or “ethical” stable non-aggressive ZPG. • All stop growing early, then poor or self-absorbed. • Only local moves, near us all stopped growing. • We are in a “zoo” or neutral zone, silence enforced. • Everyone’s hiding from predators, who wait. • This analysis: They passed by but kept going.

  6. CURRENT Mines, refinery, factories, roads, transports, generators, sensors, collectors, radiators, comm, power, construct, repair, command, launch Sensors, shields, thrust, maneuver, collectors, radiators, scouts, repair, weapons, command Seeds to Oases

  7. Colonization in Space-Time time death light colony failed max tech seeds oasis birth space (not to scale!)

  8. How Many Alien Origins? NONE ONE LOTS

  9. Just M-acts, M-stuff make, move, maintain No other aliens hinder Tech near constant First full-tech wave varied/mutable enough lasts long enough can avoid far weapons (Lots asexual selection!) M-stuff at finite oases Hard speed limit No far direct flights Easy stop oasis invade Easy see far ahead No scale gains of multi oasis use clear path My Basic Assumptions

  10. Evolutionary Game Theory • In stable environment, equilibrium same as: • each type pick acts to max its future population, given expected actions of other types. • Economists have applied to investments • log utility for correlated risk to all of type • risk-neutral for uncorrelated risk to individual • discount bequest to half-gene-kids share by half • Beware: econ math avoids functional forms

  11. r Key Concepts t Goal Region Value of grabbing this is expected number of colonies produced in goal region, weighted by where in goal region. If can go faster for long enough, nothing left for latecomers. Population Origin

  12. r t Leading Edge Selection x v # new colonies T s Fraction oases full 1 Log prob. find an open oasis. P=q=0 at Leading Edge Log expected grow between generations Log resource grow at oasis Log resources per seed Log seed mortality Seed hardness

  13. time radius • As fall behind: • stay longer, move less • seeds slower, harder • search more for oases • more seeds make it • use worse oasis types Stay behind actions:not selected forlong preserved Prefervariance Min growth rate tolerate Seed always faster than wave front Use worse oasis types Want only to be near edge Near edge, on average only one seed makes it r Results • Predictions: • Old seed debris, anisotropic • Missing old fast-grow resources • Wall of activity far away • No slow-to-make constructions • Aliens gone, or in rush to go, • or random behavior.

  14. y r x Conjectures Local cooperation in “threads” • Between galaxies: • less seed mortality per distance • more search as oases rarer • if faster between, skip galaxies • burnout stops later waves?

  15. Results Summary • At leading edge, on ave. one seed/oasis survives. • 106 seeds worth 103 penetrate twice as far. • Later generations fall farther behind leading edge, but grow in number. Seeds spend more to discern the fewer open oases, land at worse oasis types, stay there longer, and then send out more cheaper slower lower-mortality seeds less far. • Unless congestion, send identical seeds together. • Any left-behinds want to leave ASAP. • Lower limit to growth rate tolerate, % open oases.

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