In the resource-depleted future, how might we capture and utilise the energy available to us? What ingenious ideas and inventions might we put to use to feed and shelter the people of our growing worlds? Here are some of the wild and wacky ideas to be proposed.
The concept of the Dyson Sphere, developed by physicist Freeman Dyson, came about after consideration of how we could capture the full amount of solar energy. Dyson described a sphere of satellite structures that orbited the sun – or another star – and harvested most or all of the star’s total energy. He also suggested such spheres might already exist in the wider universe. While presently beyond the engineering ability of humans to build, elements of the Dyson sphere such as orbiting satellites are already in regular use.
Variants of the Dyson Sphere have been explored by scientists and science fiction writers alike. They include the Dyson Swarm, which consists of many orbiting satellites, whether simply as a ring shape or as a more complex swarm of satellites in patterns like the lines formed by segments of an orange. A Dyson Bubble, meanwhile, would have non-orbiting satellites known as statites (a portmanteau of static and satellite) held in place by light sails. At present we do not have the technological knowledge to produce such a material. Then there is the Dyson Shell, where the orbiting material is solid, but this is usually deemed unfeasible as it could collide with the star or other interstellar bodies and debris. It has also been suggested that Dyson Spheres be built closer to the star or even a submerged shell around the core of the star.
Stellar engines are another example of hypothetical energy-capturing megastructures, some of which are similar in design to Dyson structures. Examples include Shkadov thrusters, proposed by Leonid Shkadov. They are propulsion systems which, like the statites described above, are held in place by enormous light sails. The idea behind such a system is that radiation is asymmetrically emitted, so the statite is pulled along behind the star.
Other stellar engines, such as Matrioshka Brains, described by Robert Bradbury, use the temperature difference between the star and its interstellar surroundings for energy capture, for example by means of heat engines. The Matrioshka Brain was proposed with the idea that it would be used solely for driving computing systems. In science fiction the realms of possible uses have included processing uploaded human brains in virtual reality and simulating alternate universes.
The two ideas, propulsive system and thermal energy-capturing systems, could also be combined. One example of a combination system is a Dyson Shell with a mirrored interior. Like the Dyson Sphere and its variants, various types of stellar engine have been explored in science fiction and popular culture.
While a Dyson Sphere is not going to help us out in providing a cheap energy supply anytime soon, some of the concepts are theoretically possible if presently rather unfeasible. But could it be that our descendants power their futuristic needs by such means?