In a fantastical animated essay, the ever-insightful Kurzgesagt explains the concept of a Dyson Sphere, a megastructure that encompasses the sun in order to capture a large percentage of its energy and direct it outward to other planets should the Earth grow cold. While this is only a theoretical experiment, the strategy behind this particular solution seems somewhat doable with a lot of money and time.
If humans want to expand into space, it will take us incredible amounts of energy. How do we do that? Easy: we will just use the sun’s energy by realizing the most ambitious construction project in history. This is how it works.