Dyson sphere
Although such megastructures are theoretically possible, building a stable Dyson sphere system is currently beyond humanity's engineering capacity. The number of craft required to obtain, transmit, and maintain a complete Dyson sphere exceeds present-day industrial capabilities. George Dvorsky has advocated the use of self-replicating robots to overcome this limitation in the relatively near term. Some have suggested that such habitats could be built around white dwarfs and even pulsars.