A Type I civilization is one that controls the energy resources of an entire planet. This civilization can control the weather, prevent earth- quakes, mine deep in the earth's crust, and harvest the oceans. This civilization has already completed the exploration of its solar system. A Type II civilization is one that controls the power of the sun itself. This does not mean passively harnessing solar energy; this civilization mines the sun. The energy needs of this civilization are so large directly consumes the power of the sun to drive its machines. The civilization will begin the colonization of local star systems. A Type III civilization is one that controls the power of an entire galaxy. For a power source, it harnesses the power of billions of star systems. It has probably mastered Einstein's equations and can manipulate space-time at will. The basis of this classification is rather simple: Each level is categorized on the basis of the power source that energizes the civilization. Type I civilizations use the power of an entire planet. Type II civilizations use the power of an entire star. Type III civilizations use the power of an entire galaxy. This classification ignores any predictions concerning the detailed nature of future civilizations (which are bound to be wrong) and instead focuses on aspects that can be reasonably understood by the laws of physics, such as energy supply. Our civilization, by contrast, can be categorized as a Type 0 civilization, one that is just beginning to tap planetary resources, but does not have the technology and resources to control them. A Type 0 civilization like ours derives its energy from fossil fuels like oil and coal and, in much of the Third World, from raw human labor. Our largest computers can- not even predict the weather, let alone control it. Viewed from this larger perspective, we as a civilization are like a newborn infant. Although one might guess that the slow march from a Type 0 civilization to a Type III civilization might take millions of years, the extraordinary fact about this classification scheme is that this climb is an exponential one and hence proceeds much faster. • Dr. Michio Kaku