ESL Blogs

Energy flows. It moves from one region to another. It bumps into constraints as it flows, and causes these constraints to change: perhaps to heat up, or perhaps to move. The specific effect on the constraint depends on how the energy flow interacts with it. The key point here is that these interactions are repeatable - they happen in the same way every time. This means that people can study the characteristics of these energy streams in a scientific manner. Using the knowledge gained from their observations they can then engineer various kinds of constraints so that the end effect of an energy flow produces something of value. For example, the flow of heat from a hot gas in one container to a cooler gas in another can result in a light bulb glowing brightly enough for someone to read a math book. That is a valuable result.