Closed system

A closed system is a physical system that does not allow transfer of matter in or out of the system, though, in different contexts, such as physics, chemistry or engineering, the transfer of energy is or is not allowed. In the context of the earth, the best was to think of it is as a spaceship. We are onboard a physical, self sustaining object floating through space powered by the sun. Sun hits the earth and is photosynthesised into carbon by immobile plants and letting off waste oxygen. The carbon is ingested alongside oxygen to make the building blocks of mobile animals. These animals eat the seeds of the plants and mobilise them via their faeces. The spaceship