Kardashev scalehow much energy makes a civilization advanced
From control of fire to black hole power, this page follows the game's entries along the history of energy and explains the Kardashev scale of civilizations.
This page is about the link between humanity's history of energy and an idea for ranking civilizations by energy, the Kardashev scale. One thing first: the game has no dedicated "Kardashev data table". The material here comes from the twenty entries in the "Energy" column of the Tree of Civilization, plus a letter in the game about the Kardashev ranking, plus several related real studies. Put together, they show how humans went from lighting the first fire to where we are now, and where we mean to go.
What the scale is
Nikolai Kardashev ranked civilizations by energy: one planet, one star, one galaxy. Humanity is now at about 0.73. Each step up multiplies the energy by about ten billion. His paper was published in 1964 and divided civilizations by the energy they can use into three types: planetary, stellar and galactic (Kardashev, Soviet Astronomy, 1964). Its original title is "Transmission of information by extraterrestrial civilizations".
An earlier step was Freeman Dyson's 1960 idea: an advanced civilization would surround its star with countless light collectors and give itself away in the infrared (Dyson, Science, 1960). Whether a civilization can be spotted depends on how much energy it uses and how much waste heat it gives off.
Humanity's energy timeline
| Entry | One fact |
|---|---|
| Control of fire | Ashes and burned bones from Wonderwerk Cave in South Africa, about 1 million years old, are among the earliest evidence of human use of fire. |
| Cooking | One hypothesis holds that cooked food let humans get more energy from less food, so the gut got shorter and the brain bigger. |
| Animal power | The plow and the ox cart let one farmer work much more land. |
| Waterwheel | Both ancient Greece and Han China had waterwheels, the first mechanical power for humans that did not rely on muscle. |
| Windmill | The Persians built the first windmills, to grind grain and pump water. |
| Coal | Kaifeng, capital of the Northern Song, already burned coal in large amounts. The fern forests of the Carboniferous, once buried, became most of today's coal. |
| Steam engine | The steam engine James Watt improved in 1769 freed factories from dependence on rivers and sped up the Industrial Revolution. |
| Oil | In 1859 Edwin Drake drilled the first commercial oil well in the United States. Oil comes mainly from plankton in ancient seas. |
| Internal combustion engine | In 1876 Nikolaus Otto built the four-stroke internal combustion engine, and cars and airplanes started from it. |
| Power plant | In 1882 Thomas Edison built the first commercial power station in New York. |
| Nuclear fission power | In 1942 Enrico Fermi built the first nuclear reactor. In 1954 the Obninsk plant in the Soviet Union first supplied power to a grid. |
| Solar cells | In 1954 Bell Labs made the first practical silicon solar cell, with an efficiency of about 6%. |
| Lithium-ion battery | Sony launched the commercial lithium-ion battery in 1991. Its three inventors won the 2019 Nobel Prize in Chemistry. |
| Controlled fusion | In 2022 the US National Ignition Facility for the first time got fusion to release more energy than the laser energy that hit the fuel. |
Each jump on this timeline gave humans a bit more energy to use: from muscle, to water and wind, to coal, oil and electricity, and finally nuclear power. But even today humanity is still at 0.73, short of reaching even the whole "planetary" level.
A few steps that have not happened yet
Each item below is an idea not yet realized, not something that has happened.
- Space solar power station: Collect sunlight in space, free of day, night and weather, and beam it back to the ground by microwave.
- Antimatter engine: Matter and antimatter annihilate and turn all their mass into energy, a hundred times more efficient than nuclear fusion. But making 1 gram of antimatter takes far more energy than it can release.
- Dyson swarm: The countless light collectors around a star, which is Dyson's idea above.
- Star lifting: Use strong magnetic fields to draw matter off a star's surface, which both yields materials and can extend the star's life.
- Black hole power: In 1969 Roger Penrose pointed out that energy can be extracted from the ergosphere of a rotating black hole, up to about 29% of the black hole's mass.
The science of energy
- James Clerk Maxwell unified electricity and magnetism and calculated that the speed of electromagnetic waves equals the speed of light exactly: light is an electromagnetic wave (Maxwell, Philosophical Transactions of the Royal Society, 1865). This is the theoretical root of the age of electricity.
- Bethe worked out that stars shine by nuclear fusion, which solved the puzzle of how the Sun can burn for billions of years (Bethe, Physical Review, 1939).
- A ground-based laser array pushing an extremely light sail could accelerate a probe to one fifth of the speed of light (Lubin, Journal of the British Interplanetary Society, 2016). It is one example of "using energy for long journeys".
Want the originals? Search for these titles
- Kardashev (1964): "Transmission of information by extraterrestrial civilizations"
- Dyson (1960): "Search for artificial stellar sources of infrared radiation"
- Maxwell (1865): "A dynamical theory of the electromagnetic field"
- Bethe (1939): "Energy production in stars"
- Lubin (2016): "A roadmap to interstellar flight"
Real basis
Control of fire: Ash and burnt bones about 1 million years old from Wonderwerk Cave in South Africa are some of the earliest evidence of humans using fire.
Cooking: One hypothesis says cooked food let humans get more energy from less food, so the gut shrank and the brain grew.
Animal power: The plow and the ox cart let one farmer work far more land.
Waterwheel: Ancient Greece and Han China both had water wheels, the first mechanical power humans got without using muscle.
Windmill: The Persians built the first windmills, used to grind grain and pump water.
Coal: Kaifeng, the Northern Song capital, already burned coal in huge quantities. Most of today's coal is the buried remains of Carboniferous fern forests.
Steam engine: Watt's improved steam engine of 1769 freed factories from dependence on rivers and sped up the Industrial Revolution.
Oil: In 1859 Drake drilled the first commercial oil well, in the United States. Oil mostly comes from plankton in ancient seas.
Power plant: In 1882 Edison built the first commercial power station, in New York.
Internal combustion engine: Otto built the four-stroke internal combustion engine in 1876; cars and airplanes both started from it.
Nuclear fission power: Fermi built the first nuclear reactor in 1942; in 1954 the Soviet Obninsk plant fed power into a grid for the first time.
Solar cells: In 1954 Bell Labs built the first practical silicon solar cell, with an efficiency of about 6%.
Modern wind power: The generators of large wind turbines often use neodymium-iron-boron permanent magnets; one offshore turbine needs hundreds of kilograms of rare earths.
Lithium-ion battery: Sony launched the commercial lithium-ion battery in 1991; its three inventors won the 2019 Nobel Prize in Chemistry.
Controlled fusion: In 2022 the US National Ignition Facility got fusion to release more energy than the laser energy that hit the fuel, for the first time.
Space solar power station: Collects sunlight in space, unaffected by day, night or weather, and beams it to the ground as microwaves.
Antimatter engine: Matter–antimatter annihilation turns all the mass into energy, hundreds of times more efficient than fusion. But making 1 g of antimatter takes far more energy than it can release.
Dyson swarm: Dyson proposed in 1960 that advanced civilizations would surround their stars with countless light collectors, giving themselves away in the infrared.
Star lifting: Use strong magnetic fields to pull matter off a star's surface, gaining raw material and also extending the star's lifetime.
Black hole power: Penrose pointed out in 1969 that energy can be extracted from a rotating black hole's ergosphere, up to about 29% of the hole's mass.
Kardashev ranked civilizations by energy: one planet, one star, one galaxy. Humanity is at about level 0.73 now. Each level up needs about ten billion times more energy.
Related research
These studies relate to this topic but are not direct proof of this page.
What powers the stars: Bethe calculated that stars shine by nuclear fusion, solving the puzzle of how the Sun can burn for billions of years.
Source: Bethe, Physical Review 1939, "Energy production in stars"
Electromagnetic field theory: Maxwell unified electricity and magnetism and calculated that the speed of electromagnetic waves equals the speed of light: light is an electromagnetic wave.
Source: Maxwell, Philosophical Transactions of the Royal Society 1865, "A dynamical theory of the electromagnetic field"
Dyson sphere: A sufficiently advanced civilization might wrap its star, and we could find it through anomalous infrared radiation.
Source: Dyson, Science 1960, "Search for artificial stellar sources of infrared radiation"
Scale of civilizations: Sorts civilizations into three types by the energy they can use: planetary, stellar and galactic.
Source: Kardashev, Soviet Astronomy 1964, "Transmission of information by extraterrestrial civilizations"
Light sails to the stars: Pushing ultralight light sails with a ground-based laser array could accelerate probes to one fifth the speed of light.
Source: Lubin, Journal of the British Interplanetary Society 2016, "A roadmap to interstellar flight"
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