Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

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    TYPE I, II, AND III CIVILIZATIONS
    How will this exponential rise in energy continue into the coming centuries and millennia? When physicists try to analyze civilizations, we rank them on the basis of the energy they consume. This ranking was first introduced in 1964 by Russian astrophysicist Nikolai Kardashev, who was interested in probing the night sky for signals sent from advanced civilizations in space.
    He was not satisfied with something as nebulous and ill defined as an “extraterrestrial civilization,” so he introduced a quantitative scale to guide the work of astronomers. He realized that extraterrestrial civilizations may differ on the basis of their culture, society, government, etc., but there was one thing they all had to obey: the laws of physics. And from the earth, there was one thing that we could observe and measure that could classify these civilizations into different categories: their consumption of energy.
    So he proposed three theoretical types: A Type I civilization is planetary, consuming the sliver of sunlight that falls on their planet, or about 10 17 watts. A Type II civilization is stellar, consuming all the energy thattheir sun emits, or 10 27 watts. A Type III civilization is galactic, consuming the energy of billions of stars, or about 10 37 watts.
    The advantage of this classification is that we can quantify the power of each civilization rather than make vague and wild generalizations. Since we know the power output of these celestial objects, we can put specific numerical constraints on each of them as we scan the skies.
    Each type is separated by a factor of 10 billion: a Type III civilization consumes 10 billion times more energy than a Type II civilization (because there are roughly 10 billion or more stars in a galaxy), which in turn consumes 10 billion times more energy than a Type I civilization.
    According to this classification, our present-day civilization is Type 0. We don’t even rate on this scale, since we get our energy from dead plants, that is, from oil and coal. (Carl Sagan, generalizing this classification, tried to get a more precise estimate of where we ranked on this cosmic scale. His calculation showed that we are actually a Type .7 civilization.)
    On this scale, we can also classify the various civilizations we see in science fiction. A typical Type I civilization would be that of Buck Rogers or Flash Gordon, where an entire planet’s energy resources have been developed. They can control all planetary sources of energy, so they might be able to control or modify the weather at will, harness the power of a hurricane, or have cities on the oceans. Although they roam the heavens in rockets, their energy output is still largely confined to a planet.
    A Type II civilization might include
Star Trek
’s United Federation of Planets (without the warp drive), able to colonize about 100 nearby stars. Their technology is barely capable of manipulating the entire energy output of a star.
    A Type III civilization may be the Empire in the
Star Wars
saga, or perhaps the Borg in the
Star Trek
series, both of which have colonized large portions of a galaxy, embracing billions of star systems. They can roam the galactic space lanes at will.
    (Although the Kardashev scale is based on planets, stars, and galaxies for its classification, we should point out the possibility of a Type IV civilization, which derives its energy from extragalactic sources. The only known energy source beyond our galaxy is dark energy, which makes up 73 percent of the matter and energy of the known universe, while the world of stars and galaxies makes up only 4 percent of the universe. A possiblecandidate for a Type IV civilization might be the godlike Q in the
Star Trek
series, whose power is extragalactic.)
    We can use this classification to calculate when we might achieve each of these types. Assume that world civilization grows at the rate of 1 percent each year in terms of its collective GDP. This is a reasonable assumption when we average over the past several centuries. According to this assumption, it takes roughly 2,500 years to go from one civilization to the next. A 2 percent growth rate would give a transition period of 1,200 years.
    But we can also calculate how long it would