If I leave my home alone, untouched, it soon descends into disorder: dust collects, paint peals off, wood rots, and leaks form. To prevent this degradation I need to periodically dust, vacuum, paint, replace boards, and fix leaks.
Another way to phrase this is: I must put energy and materials into my home to create order.
Still another way of stating it is: when my home is a “closed system” disorder increases. By making my home an “open system” I can import energy and matter into it to add order.
These ideas of closed/open systems and order/disorder are very important.
Here’s an excellent description of these ideas from the book The Origin of Wealth by Eric D. Beinhocker:
The universe itself is a system, and within that largest of all systems, one can define any number of smaller systems. For example, our planet is a system, as is your body, your house, or a bathtub full of water. A closed system is a system having no information flowing into or out of it. The universe itself is a closed system.
Energy might be converted into matter, and vice versa, and energy might be converted into different forms within the system, but the total amount is constant. In addition, the total disorder (entropy) in a closed system is always increasing to its maximum level, as order decays into disorder and the system eventually comes to rest.
The second type of system is an open system, with energy and matter flowing into and out of it. Such a system can use the energy and matter flowing through it to temporarily fight entropy and create order, structure, and patterns. Our planet, for example, is an open system; it sits in the middle of a river of energy streaming out from the sun. This flow of energy enables the creation of large, complex molecules, which in turn have enabled life, thus creating a biosphere that is teaming with order and complexity. Entropy has not gone away; things on the earth do break down and decay and all organisms eventually die. But the energy from the sun is constantly powering the creation of new order. In open systems, there is a never-ending battle between energy-powered order creation and entropy-driven order destruction.
Nature’s accounting rules are very strict, and there is a price to be paid when order is created in an open system. For order to be created in one part of the universe, order must be destroyed somewhere else, because the net effect must always be increasing entropy (decreasing order). Thus, as the sun powers order creation on earth, all of that life and activity creates heat, which is radiated back into space. The heat has a randomizing effect wherever it ends up, thereby increasing entropy. The earth thus imports energy and exports entropy.
Closed systems always have a predictable end state. Although they might do unpredictable things along the way, they always, eventually, head toward maximum entropy equilibrium (at rest, unchanging). Open systems are much more complicated. Sometimes they can be in a stable, equilibrium-like state, or they can exhibit very complex and unpredictable behavior patterns that are far from equilibrium. [Example, sometimes my home is in a steady, unchanging condition. Sometimes I let it go and it becomes very messy. Sometimes I get motivated and get it in spotless shape.] In an open system there may be patterns such as exponential growth, radical collapse, or oscillations. As long as an open system has free energy, it may be impossible to predict its ultimate end state or whether it will ever reach an end state.