The Kardashev Scale: Advanced Civilizations

and

How To Detect Them

By Deuce of FurryMUCK

Art by Richard Bartrop (http://rjbartrop.deviantart.com)

2

What Is the Kardashev Scale?

• Premise:

– Any civilization will want to use all the power available to it.

• Consequence:

– End up capturing and using all of the power of the planet, star, or galaxy they’re based on.

– Especially attractive for virtual/upload societies. Thought/computation requires energy per bit flip.

3

What Is the Kardashev Scale?

• Extension: Higher Levels

– Type IV: (visible) universe

– Type IV: supercluster, Type V: universe

• Extension: Logarithmic Scale

– Pick values for total power of each Type.

– Take logarithm of each Type’s value.

– Interpolate to turn a given power value into a fractional Type level.

4

Presentation Outline

• This could actually be done without magic. – Takes a while, but far shorter than the lifetime of the

celestial object being tapped.

• For each type: – Methods of capturing most or all of the host’s power.

– What this would look like if observed from a distance.

• If Kardashev-scale civilizations exist, we may be able to detect them.

5

Type I: Planet’s Power

6

Type I: Planet’s Power

• Many power sources. Choose the biggest.

• Inner system planet: Heat from its sun. – Direct form: Light on and above the surface.

– Indirect forms: Air and ocean currents.

• Outer system gas giant: Contraction. – “Kelvin-Helmholtz mechanism”. Planets like Jupiter

get more heat from this than from their sun.

– Direct form: Thermal IR into space.

– Indirect forms: Air and mantle currents.

7

Planet’s Power: Sunlight

• Want direct capture, not indirect.

– Conversion works best if heat source is very hot.

– For photovoltaic, spectral temperature of sunlight is

high (photon energy >> kT).

– For focused-mirror thermal, can get as hot as the

surface of the Sun.

• Direct capture methods:

– Plating the surface.

– Orbiting swarm.

8

Planet’s Power: Sunlight

• Plating the Planet

– Photovoltaic or heat engine; looks the same.

– Planet surface is coal-black.

– No atmosphere (it absorbs light).

– Surface temperature uniform if power distributed; if

not, varies with latitude.

• Observables:

– Altered features in planet’s spectrum.

– Communications hidden (fiber or other waveguide).

9

Planet’s Power: Sunlight

• Normal planet has modest reflection (“albedo”), many absorption lines from weather/air, varied surface composition.

• Kardashev planet has very little reflection, no air absorption, uniform surface composition, and maybe heat spectrum features (single-temp, or city hot spots).

10

Planet’s Power: Sunlight

• Orbiting Swarm – Does not capture all light; there’d be too much

satellite overlap.

– Satellites are coal-black, as with plating.

– Satellite temperature varies with latitude.

– Planet surface is industrialized (to make replacement satellites).

– Planet surface is communications routing mesh.

• Observables: – Swarm has modified spectrum (as with plating).

– Planet spectrum still visible.

– Last-mile communication visible.

11

Planet’s Power: Sunlight

• Kardashev planet has low reflection, satellite material

spectrum, a bit of planet spectrum, no atmosphere.

• Communication needs as much bandwidth as it can get.

Bands are 4kT IR (show up against planet) and UV

(show up against sunlight).

12

Planet’s Power: Internal Heat

• Direct capture easiest.

– Orbiting swarm.

– Must be far from the planet, so radiators cooler than planet’s IR.

– Mass replenished from moons.

• Indirect capture: Inside an ice giant

– Planet-scale wind farm.

– Mass replenished from planet.

13

Planet’s Power: Internal Heat

• Orbiting Swarm. – Want at least 2x colder for heat engine, 4x colder for

photovoltaic.

– Puts swarm at 4x or 16x planet radius.

– Coal-black at IR wavelengths.

– Doesn’t completely obstruct planet.

– Uses point-to-point communication.

• Observables: – Swarm looks like a huge, cool object with funny

spectrum.

– Actual planet is still visible.

– Communications very visible.

14

Planet’s Power: Internal Heat

• Normal giant looks like hot ball of hydrogen compounds with lots of chemistry lines.

• Kardashev giant looks like huge cloud of rocky or sooty dust with uniform composition and temperature. Planet shines through. Very bright artificial-looking communications light (IR or UV).

15

Planet’s Power: Internal Heat

• Ice giant has methane and ammonia but little hydrogen (Uranus, Neptune).

– Aircraft, gliders, sails, and balloons function.

– Can harvest CHON from atmosphere.

• Power transport within planet is by convection.

– All matter is a great insulator on this scale.

– Any given atmosphere layer handles the entire planet’s power transport.

16

Planet Power: Internal Heat

• Floating Wind Farm – Must control weather on a planetary scale.

– Biggest hazard: storms. Alter atmosphere to have laminar flow and gentle gradients.

– May or may not be possible to do this with normal materials.

• Observables: – If in upper atmosphere layers, strong spectral lines of

artificial materials.

– Suppressed storms means no lighting and less mixing between atmosphere layers. Inner layers hidden.

– Communications, unless atmosphere absorbs.

17

Planet Power: Internal Heat

• Normal ice giant looks like a cool ball of hydrogen-

bearing compounds with storm RF and chemical mixing.

• Kardashev ice giant looks like a cool ball of simple

hydrogen compounds with no mixing and no RF.

• Possible communications glow.

18

Planet Summary

• Sun-lit rocky planets have light absorbed by

plating or by swarms.

• Warm gas giants and brown dwarfs have IR

absorbed by swarms.

• Detect via modified spectra:

– Coal black, no air, weird composition, and

communications, for sun-lit rocky planets.

– Shrouded in dust with bright communications light, for

giants.

19

Type II: Star’s Power

20

Type II: Star’s Power

• Baseline: Main-sequence star.

– Power radiated as light.

– Near-surface transport by convection.

• Comparable: Binary accretion system.

– Stellar remnant pulls material from a partner.

– Accretion disk glows very brightly.

– Nova risk.

21

Star Power: Light

• “Dyson Swarm” of satellites to capture light. – Mass replenished by planets.

– Have to be at least 4x star radius for heat engine, 16x for photovoltaic, per gas giant.

– Have to be at least 10x orbital distance from a binary star system.

• Want it to be a single shell and close, for minimum mass. – “Matrioshka brain” is energy-efficient but has abysmal

mass efficiency.

22

Star Power: Light

• Main-Sequence Star Observables:

– Swarm is cooler than star.

– Swarm has no absorption lines, weak reflection lines.

– Like natural ejected shell, not coupled to stellar seismology.

– Unlike natural ejected shell, moving tangentially very fast (orbiting), not moving radially.

– Communications band in UV and very bright.

23

Star Power: Light

• Normal star has atmosphere chemistry lines, little dust, shells move radially.

• Kardashev star has “dusty shell” spinning at orbital speed with strange composition, communications band glowing brightly.

24

Star Power: Light

• Accreting Binary Observables:

– Looks like a cloud of dust or soot obscuring binary.

– Binary is almost a point source. If satellites are large, may see flicker or a step pattern as satellites overlap part of it.

– Avoids polar jets (no impact radiation).

– Communication might be by reflection.

– Only built when disk outshines companion star.

25

Star Power: Light

• Step-patterns in disk emission vs time.

• Glittering (scintillation) if using reflected light.

• Bright communications band in blue or UV if not.

• Strange “dust” composition spectrum.

26

Stellar Power: Exotic Methods

• Most of these require magic.

• Main sequence star: in-atmosphere.

– Carbon-rich red dwarf. Look for complex materials and etched soot.

• Accreting binary: on-surface.

– Magic chemistry (degenerate or nuclear).

– Look for a too-warm binary that doesn’t nova.

• Pulsar: magnetic cage.

– Look for gravitational lensing; it’s heavy.

27

Star Summary

• Look for strange clouds of “dust” around

stars or accreting binaries.

• Star shells show tangential motion, are

mostly-opaque, and uniform temperature.

• Binary shells glitter and eclipse the

accretion disk.

• Both show communications bands brightly.

28

Type III: Galaxy’s Power

29

Type III: Galaxy’s Power

• Mature galaxy: Power produced by stars.

– Can turn all stars into K-II civilizations.

– Looks like a very dim, dusty galaxy.

• We see these!

– Communications would be very, very visible.

• Communications bottleneck.

– Star to star bandwidth is too low to share star-

shell’s information.

30

Type III: Galaxy’s Power

• Young galaxy: Power produced by black hole. – Young, active galaxies emit massive amounts of

energy due to this.

– We still see them today, as quasars.

• Can tap with a swarm around the central black hole. – Constantly disrupted by infalling stars.

– Disk is bright enough to be a hazard.

– Secondary radiation from jet impact is a hazard.

• Did super-civilizations all live and die long ago?

31

Type III: Galaxy’s Power

• Magic option: Black hole computer. – Properties of a black hole look an awful lot like those

of the best possible computer.

– Stores maximal amount of information in a given volume.

– Hawking temperature consistent with maximum possible computing rate.

– Computing rate, radius, and information content balance just right for serial computation.

• Probably not possible, but if it were, this is where super-civilizations would upload to.

32

Type IV: Universe’s Power

33

Type IV: Universe’s Power

• Easy way: Convert all stars everywhere to

K-II.

– This doesn’t work. Takes longer than the age

of the universe to spread out, and

communications problem is ultra-bad.

• Philosophical way: Universal computer.

• Clarke-tech way: Basement universe.

34

Type IV: Universal Computer

• ADS/CFT correspondence (“Holographic Principle”). – Region of space, containing matter and governed by

laws, can be mapped on to the surface bounding that space, with different but corresponding laws.

– Can apply the same principle to the entire universe.

– Large becomes small, small becomes large, local becomes non-local, and vice-versa.

– If computation were being performed with CFT laws, we’d never notice it, because ADS signs would be the size of the universe.

• In practice, doubtful. No free computation, and works for bounded volumes (like black holes).

35

Type IV: Basement Universe

• Enough energy in one place can make a new

mini-universe.

– Works by restarting cosmic inflation locally.

– Scale unclear. Could be GUT, could be Planck.

• Conventional accelerators can’t do this.

– Would be the size of the galaxy.

– Interaction cross-section would be too low.

• Proposed architectures might work.

– Winterberg accelerator.

36

Type IV: Basement Universe

• Problem: Exchanging information. – Baby universe interior is expanding FTL.

– Exterior likely “pinches off” very quickly.

– Proposed workaround: Imprint info at creation.

– Proposed workaround: Wormhole link.

• Problem: Different laws. – “String theory landscape”: Many laws and parameters

set by chance.

– Baby universe will have random choices for these.

– Proposed workaround: Choose laws (how?).

37

Concluding Remarks

• Kardashev scale is a useful way of describing how “super” a super-civilization is.

• Kardashev Type I (planet) and Type II (star) can be done without magic. – Observation signatures that we might detect.

• Kardashev Type III (galaxy) and Type IV (universe) require more magic, but are neat.

• Fun and thought-provoking to think about!