The Second Law of Thermodynamics
I have spoken at great length with many about the principles underlying the second law of thermodynamics. In common language, many have repeated what seems to be a common University-founded concept; the principle is most commonly expressed with the following idiom:
In a closed system, entropy always increases.
In this case, entropy is seen as the level of chaos or randomness of a system, a measure of disorder. So, we are really suggesting that a closed system will become more and more disordered as time progresses...
This does make sense. If the thermodynamic variables of a system ar not allowed to dissipate, temperature and pressure will not decrease. Likewise, if temperature does not decrease, interacting particles will interact without loss, creating higher and higher energy states. This increase in energy corresponds to higher entropy, greater disorder, less stability and increased simplicity.
Trying to understand the second law of thermodynamics can be intimidating. The law is generally expressed with caveats that allow for oft incorrect interpretation. Wikipedia offers the following on the subject (Laws of Thermodynamics, Wikipedia):
The entropy of an isolated system consisting of two regions of space, isolated from one another, each in thermodynamic equilibrium in itself, but not in equilibrium with each other, will, when the isolation that separates the two regions is broken, so that the two regions become able to exchange matter or energy, tend to increase over time, approaching a maximum value when the jointly communicating system reaches thermodynamic equilibrium.
This language, while being overwhelmingly precise is not exceptionally clear, as it does not make certain the direction that heat will flow in.
A combinatoric view of the Second Law of Thermodynamics
Perhaps it is worthwhile to examine the principle of thermodynamics by first understanding that this principle discusses outcomes of thermodynamic interactions; the general outcomes that arise from two seperate systems exchanging energy.
In the previous section, we laid out the difference between open and closed systems, stating that open systems allow heat and energy to dissipate through time, whereas closed systems confine energy and do not allow thermodynamic energy to escape.
The second law of thermodynamics tells us that closed systems, where energy is not allowed to dissipate, will tend to increase in disorder through time.
Conversely, open systems, where thermodynamic energy can dissipate into external systems (or be lost as space-time) will tend to increase in complexity through time, provided that the system of reference does not have an input of external energy greater than the energy dissipated.
Additionally, the second law of thermodynamics provides a general result regarding thermodynamic transactions, relating the direction of heat flow relative to a system to the resulting complexity (order) of a system. As a general rule:
If heat or energy is added to a system such that state-change is provoked, the inputted energy will decompose the original system into simpler, fractionalized pieces. The result is simpler than the original constituents.
If heat or energy is dissipated from a system such that a state-change reaction is provoked, the energy leaving the system and the corresponding decrease in internal motion will create a composite result, a more complex consequent comprised of a combination of once-simpler components.
As energy decreases and order increases, we see the elementary come together to form the composite; atoms form molecules, molecules form amino acids, amino acids form DNA, DNA forms cells, cells form tissue, tissue forms organs, organs form organism, organisms form groups and groups form societies.
While these principles seem straightforward enough, they are often taught with a granularity that hides their true value.
Consider the introductory paragraph; most University level students are taught that "In a closed system, entropy always increases," and this understanding routinely gets truncated into "entropy always increases."
if "entropy always increases," question then must become, how can disorder and chaos increase over time while still allowing for the evolution of species, a process in which complexity clearly increases through time?
Put simply, entropy will increase through time in a closed system. While this idea is readily taught, there is one caveat that seems to left out over and over again, and must be stated:
The Universe is an Open System.
