A Type 3.0 Civilization is one that controls the resources of an entire galaxy. Carl Sagan's value for the power generation required for this is 1036 watts.
Type 3.0 Civilizations are capable of accelerating celestial bodies within their local galaxy to speeds approaching the speed of light, including planets and even entire stars (though the latter would still require a large investment of resources). Movement within the galaxy for small objects, such as spaceships, is only limited by the possible accelerations, which may be very high given the presence of advanced metamaterials. Faster-than-light travel may be available, if it does not violate causality in the civilization's local universe. They may also be capable of some intergalactic travel and communication.
A Type 3.0 Civilization is capable of disassembling entire star systems and rearranging them into megastructures, and even of creating some small interstellar-scale megastructures. The construction of Dyson sphere and ringworlds is routine to them. Multiple stars could be harvested in order to construct a solid-shell dyson sphere. With some expenditure of resources, a few thousand stars could be disassembled in order to construct an Alderson disk. A significant portion of the galaxy could even be devoted to constructing a massive megastructure, such as a megaring, though this would strain the resources of a Type 3.0 civilization somewhat.
A Type 3.0 Civilization may stagnate and fail to expand successfully to nearby galaxies, eventually dying out when the stars in its home galaxy exhaust their hydrogen fuel and no free hydrogen in space exists to continue generation of energy using systems such as Bussard ramjets. If the civilization is able to spread to more galaxies, it can eventually expand to encompass the entire local universe, becoming a Type 4.0 Civilization.
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