It seems Dr. Michio Kaku is a Theoretical Physicist. He has given a very interesting explanation on Type 0/1/2/3 Civilizations in this YouTube Video. Do see it. I have given a small teaser below from that video which will enable you to guess the direction of the discussion. “When we physicists look in outer space for alien life, we don’t look for little green men. We look for Type-1/Type-2/Type-3 civilizations. A Type-1 civilization has harnessed its planetary power. They control earthquakes, the weather, volcanoes, they have cities on the ocean, anything planetary – they control. That’s Type-1 civilization.