Posted by Andrew Bone Tuesday, 20th September 2016
The First Law of Thermodynamics refers to the tendency of heat to redistribute in a closed system till all parts are at the same temperature. The direction of flow of energy is irreversible unless more energy is used.
The Second Law deals with how energy is distributed in space and time. Since it takes more energy to return a system to an energetic imbalance than was obtained from the system in the first place, the energy of the universe must be moving from a concentrated state to a perfectly distributed state. This is entropy, which can be understood as 'ever increasing disorder'.
For example, the Big Bang concentrated most energy in stars, which are depleting their fuel, reducing stars eventually to cold masses, with all their energy radiated out.
Another example is a rechargable battery: it always takes more energy to recharge a battery than can be obtained by the use of the battery. The Second Law of Thermodynamics assures us that no conversion of energy is 100% efficient - there will always be some loss - not energy lost from the universe (energy cannot be created or destroyed - there is as much energy in the universe now as one second after the Big Bang), but into a less usable form. When petrol is burned in a car engine, most of the energy released from the fuel is converted to heat and noise, and less than 10% provides motion of the vehicle.
Classical Economics has a nasty habit of assuming perfect things: perfect market, perfect production processes, perfect labour, perfect consumer behaviour. Homo economicus is anything but perfect or predictable in behaviour.
The laws of thermodynamics applied to economics assure us that there is always a loss in any exchange, and as a result waste is inevitable. Economics would like the planet's biosphere to be an infinite space, with infinite sinks for pollution, and infinite resources: the perfect waste-absorbing external system for a perfectly inefficient human economy. The human economy relies on externalities to function at all: most of these externalities are to the cost of the global environment. Entropy does not allow these to 'disappear', so the 'perfect economy' is in reality deteriorating its own habitat, and dissipating the value of its resources.
You might draw the conclusion from this that the human planet is doomed. This would be the case if it were a closed system. However, the Sun provides a supply of energy, and will continue to do so for about 4.5 billion years. Therefore, the theoretical limit to human economic capacity for inefficiency is exactly equal to the energy supplied by the Sun. If human inefficiency can be brought into balance with this long term energy equation, there is a possible future for us. The Laws of Thermodynamics permit it.