Nothing Disappears All mass and energy in the universe is conserved. Energy may be converted into different forms, but the total amount of energy in an isolated system remains constant. This principle of matter conservation and the First Law of Thermodynamics are helpful in understanding the earth as a system. For example, apart from the occasional meteorite or spaceship, the amount of matter on earth has stayed the same for billions of years. When matter is burned it is not destroyed, but transformed into waste, predominantly in the form of visible and invisible gases. Everything Spreads Energy and matter tend to spread spontaneously; everything has a tendency to disperse (the Second Law of Thermodynamics, or the Law of Entropy). Although the total amount of energy remains constant, the quantity of energy that is available in a useful form decreases with each transformation and tends to dissipate through a system. Entropy is a measure of the amount of disorder or randomness there is in a system, and in every isolated system – such as the universe – entropy always increases. Examples of this include food decaying, coloured dye in clear water dispersing, a car rusting and ice samples taken in the Arctic Circle containing measurable amounts of man-made PCBs. Thus, materials generated by, or introduced into, human society will eventually disperse in nature. There is Value in Structure We determine material quality by the concentration and structure of the matter that makes up a material. For example, food and petrol are valuable because they have a high concentration and structure. What we consume are the qualities of matter and energy – the concentration, purity, and structure of matter – and the ability of energy to perform work. We never consume energy or matter because it is neither created nor destroyed. If you drop a teacup and it breaks on the floor, much of the value from its structure is lost, but each of the original atoms is still present. Photosynthesis Pays the Bills Net increases in material quality on Earth are generated almost entirely by the sun-driven process of photosynthesis. Chloroplasts in plant cells capture energy from sunlight and form bonds that provide energy for other forms of life, such as animals. According to the Second Law of Thermodynamics, disorder increases in all isolated systems. The Earth is a closed system with respect to matter, but it is an open system with respect to energy because it receives light from the sun. It is this flow of sunlight that continues to create structure and order from the disorder.

---