The Second Law of Thermodynamics

 At the time of the Civil War in the process of manufacturing cannon barrels, experiments with the relationships between heat, energy, temperature and work upon a system, started  the developement of the physical-chemical concepts called the First, Second and Third laws of thermodynamics.

The second law in summary states that  any closed system without outside intelligent direction will gravitate to greater disorder with time and in proportion to energy expenditure upon the system until a maximum of chaos is reached.

In any exchange of energy within any isolated system
there is a force pushing it toward disorder
The second law of thermodynamics is a statement about the disorder of a system relative to factors such as temperature and the heat content of the system. Disorder is expressed as the entropy and “S” is used for it here to make calculations relative to the energy content (Q) at a given temperature of the system in consideration.  It is quite impossible to determine the total entropy of a system but the change in entropy for an ideal system can be calculated, ideal meaning a system that is not real but is an approximation used that helps in calculations. 
  For an ideal system the equation, dS = dQ/T  is the definition for the change in entropy.  Or in words, the change in entropy (or disorder) is equal to the change in heat divided by the absolute temperature of the system under ideal conditionsThe term “d” means the change and is the function used in differential equations in calculating the changes in physical-chemical or mathematical processes.  The restriction that it be an ideal system is necessary for the calculation. Ideal means that we consider only the quantities that can be practically measured because there are quantities in the total energy of any chemical system (a system having matter) that cannot be measured. 
The equation for any real system is stated by: dS > dQ/T. Or, the increase in disorder is greater than the change in energy at a given temperature.  In other words: Any spontaneous change in the energy of a system will result in an increase in disorder. (Physical Chemistry, 2nd Ed. By Daniels & Alberty, 1961 John Wiley & Sons; See Chap. 5 “The second and third law of thermodynamics, esp. pgs. 83, 88 & 94).
The study of changes in matter and their energy and order content have shown that there is a force associated with a change in energy always driving the matter in a closed system into a state of greater disorder.
Advocates of the theory of organic evolution propose that with enough time there will be a probability of order arising with the exchange of energy of a system. The use of the ideal equation for entropy change “dS = dQ/T” is used to support that concept. This would allow that there would be a finite possibility for small increases in order by chance with changes in energy. However as explained below an increase in time does not increase the probability of order arising out of disorder. And the ideal situation does not exist in the real world. When we use the equation for real systems: dS > dQ/T we face the real world and see that the more time and changes that occur, the more disorder that will result. This leads to the conclusion that life depends upon direction by intelligence outside of the system.
Another characteristic of entropy is that it is a function of the state of the system and is independent of the history or the time that preceded its current state. (Ibid p.83.) This helps us to see that it is impossible for a wrist watch to form spontaneously even in an ideal situation, absent of outside intelligent direction. The probability is the same whether it occurred in an infinite number of steps over infinite time versus happening in a few seconds in one step. It brings weight to what common sense already knows. Without outside intelligent direction there is always a force pushing any system toward disorder. Rudolf Clausius defined the second law as “Die Entropie der Welt strebt einem Maximum zu” or the entropy of the world seeks to become a maximum.
The study of the interchange between matter and energy  has demonstrated that there is a is a cause for every phenomenon.  The cause for order in the universe and in life is not chance but is from intelligent direction from an outside source.

Also see:  - how entropy applies to our lives.