How Massive Can A World Be And Still Support Life?George Dvorsky6/23/15 3:52pmFiled to: futurismgravitymegascalemegascale engineeringmegaprojectsplanetary scienceplanetsworldbuildingsciencephysicsgeology779EditPromoteShare to KinjaToggle Conversation toolsGo to permalinkAt some future juncture, we’re going to need more living space, whether it be found on another planet or through the expanse of our planet’s existing surface area. In his latest venture into worldbuilding, Oxford University research fellow Anders Sandberg explores some of the more extreme possibilities.AdvertisementFor the thought experiment, “What is the largest possible inhabitable world,” Sandberg limited his investigation to describing hypothetical worlds — both natural and artificial — with “maximal surface area that can be inhabited by at least terrestrial-style organic life of human size and is allowed by the known laws of physics.”That’s a lot to work with, including heavy super-Earths, large low-density worlds (like a carbon planet), and artificial worlds like shellworlds, gas-propped bubbleworlds, and topopolises (dubbed “cosmic spaghetti”). A depiction of a carbon world surface. “The local geology is dominated by graphite and tar deposits, with diamond crystals and heavy hydrocarbon lakes,” writes Sandberg. “The atmosphere is largely carbon monoxide and volatile hydrocarbons, with a fair amount of soot.”The most obvious candidates for natural large worlds are super-Earths, including Sandberg’s double Earth, which are rocky planets with lots of mass. He describes variations of these worlds depending on their chemical composition and density. In many cases, these large planets would take on the form of waterworlds and warm Neptunes, making habitability impossible, or at least very difficult. In one instance, he describes a hypothetical iron-rich planet 274 times heavier and 2.7 times larger than Earth featuring a surface gravity 38 times Earth’s.