Source: [[Reference Notes/Scale]] # Definitions Metabolic rate - amount of energy needed per second to keep an organism alive Metabolism - the process of transforming energy into something "useful", such as physical work, maintenance, growth and reproduction Entropy - the "useless" energy and unintended consequences that are the by-product of any energy transformation Joule - unit of energy; work done when force of 1 newton displaces a mass through a distance of 1 metre; also the energy dissipated as heat when one ampere passes througha resistance of one ohm for one second Megajoule - one million joules Watt - rate of energy use over time; 1 watt = 1 joule per second Kilowatt-hour - amount of energy delivered by 1000 watts over an hour = 1000 joules x 3600 seconds = 3.6 megajoules # Notes The average person needs about 2,000 food calories a day. This is equivalent to 90 watts, which is the requirement of a standard incandescent lightbulb. This is our *biological metabolic rate*. We have also built complex social structures that involve homes, heating, lighting, cars, airplanes, computers, etc. This means that in the US, a person now consumes 11,000 watts. This *social metabolic rate* is equivalent to the needs of a dozen elephants. > Energy is primary. It underlies everything that we do and everything that happens around us ... This may seem self-evident, but it is surprising how small a role, if any, the generalized concept of energy plays in the conceptual thinking of economists and social scientists. Economic models often refer to human labour and technology as factors of production. However, by ignoring the role of energy, they miss the crucial point that human labour without energy is a corpse, and technology wtihout energy is mere sculpture. The other thing that economists ignore is entropy. > There is always a price to pay when energy is processed; there is no free lunch ... "unintended consequences" in the form of inaccessible disorganized heat or unusable products are inevitable. In other words, every time we eat, we'll have to go to the bathroom sooner or later.