Michio Kaku adapts the Kardashev scale to describe how advanced civilizations are by the amount of energy they can control: Type 0 (like us) uses limited planetary resources such as fossil fuels; Type I can harness all energy available on its planet; Type II can capture most of the energy of its star; and Type III can use the energy output of an entire galaxy. On top of that, you could imagine a speculative Type IV civilization that harvests energy embedded in the fabric of the universe itself, such as the ubiquitous dark-matter or dark-energy–like fields between galaxies, and a Type V that somehow taps into energy sources outside our own universe “grid,” drawing power from a higher-dimensional or multiverse realm beyond our spacetime.