According to Sonntag in his book Fundamentals of Physics, one excellent definition of thermodynamics is that it is the science of energy and entropy. Another good definition would be that thermodynamics is the science that deals with heat and work and the properties of substance that bear a relation to heat and work. As I understand it, thermodynamics had something to with anything that involves the use and transfer heat or energy, and the resulting work it produces. This means that without heat or energy then there would be no work to be performed. And when work is absent then there would be no human existence for life is closely tied with activities. Like all sciences, thermodynamics was established based on experimental observation. Out of this experiments evolved the three laws of thermodynamics (Sonntag 16).
The first law of thermodynamics is often called the Law of Conservation of Energy which states that energy cannot be created nor destroyed. Furthermore, this law suggests that since energy cannot be created or destroyed it is merely transferred from one system to another in many forms. In other words, there is an idea of energy conversion like from heat energy to mechanical energy. Because energy is not created or destroyed, in the universe as a closed system the amount of energy available is constant (there is no addition or subtraction of energy) .
Energy is usually introduced into a system and from thereon undergoes energy transformation to perform some functions(Young 534-536) . In relating to life, a good example would be when a man takes in food (introduction of energy to the body through calorie), heat energy in the form of calorie is transform into chemical energy by his cells which in turn is transform into a mechanical energy so that a man is able to perform physical activities like walking, dancing or talking.
Man by his own self cannot create his own energy (he needs to eat to get energy) and that this energy through bodily processes is transform within his body to enable him to perform some bodily functions. What the first law actually is trying to say is that man just cannot get something out of nothing like he just cannot survive without first eating some amount of food; otherwise he will just fell dead. If only man can create his own energy then he does not need to eat. In the same way, the survival of other living things depend on getting energy from outside sources, for example plants need the energy of the sun for photosynthesis. For objects, in order for it to function, like for a plane in order for it to fly it needs the heat of combustion of its fuel to do work in propelling the plane (Young 534).
While the first law deals with the conservation of energy, the second law tells of the direction of conservation. In other words, how or where energy transformation normally proceeds. The second law settles the question why when you put ice into a hot cup of tea, heat will flow from the hot tea to the cold ice and melt the ice in the beloved beverage illustrating the unalterable reality that heat cannot be transferred from a colder to a hotter body. It is because natural processes that involve energy transfer must have one direction, and all natural processes are irreversible.
That is why, man as human being that makes use of many bodily energy conversions can never go back to being an infant but must proceed to old age. Or that a machine will go from new to old, it depreciates and lowers in value. In a sense, the second law puts limitations into how heat conversion is achieved in real life.
The second law further states that the direction of thermodynamic processes is more towards from an order to a disorder state or entropy. Entropy is the measure of the disorder or randomness of energy and matter in a system, the higher is a disorder the greater is the entropy. That is why in hot and cold bodies the process proceeds from hot to cold because adding heat to a body increases its disorder because it increases average molecular speeds and therefore the randomness of molecular motion(Young 574). In other aspects, it is clear now why it is easy to mess up than to clean, and that the greater are the things present the messier it is.
According to Young in his book University Physics, in a natural irreversible isolated system (one that does no work on its surroundings) entropy is always increasing, or the degree of disorder increases with time( Young 541 and579) . This can be illustrated by man getting old. Although some scientific researches had created formulas to make man look younger than his age, this only controls the pace of his getting old, but eventually man had to surrender to the irreversible natural process of body deterioration that will lead to old age and ultimately death. As man increased in age, his body weakens, his cells degenerate and eventually he dies.
And when a body decays and die it cannot be renewed again and bring back to life but it will rot on the grave . What the second law of thermodynamics is saying is that there are some things that I cannot control from happening for it is a natural process that needs or must occur and when it did occur it is impossible to undo. This reminds me in some sense of where man is heading in life. He always go towards the future and leaves behind a past. What happened in the past he can never undo for he can never go back to the past. That direction will be forever close to him no matter how much energy he is willing to spend to retraced back to that road.
Critics in the biological evolution however, claimed that the theory of evolution violates the second law of thermodynamics, since evolution involves simple life forms developing on their own into more complex, more highly ordered organisms. But living things are not closed systems because they can interact with outside sources of energy like the sun and it has been shown that energy and/or mass flow through a system can constrain it far from equilibrium, resulting in an increase in order. The organizing work is then primarily carried on by metabolic motor of DNA, enzymes, etc( ).
Third law of Thermodynamics
The third law touches on reaching a state of absolute zero (oK) or to avoid entropy by making temperature equals to zero. At absolute zero the system has a minimum total internal energy (kinetic plus potential). This can only happen if all energy and matter are randomly distributed in space eradicating all thermal motion( Young 574). This however will never occur unless perhaps in few extraordinary, carefully-engineered situations. The third law of thermodynamics reinforced the fact that in life there are things that are unattainable and accepting this reality is a much better idea than to fight the laws of life.
The laws of thermodynamics just clearly put into much clearer terms the laws of life. Since thermodynamics is a science that deals with energy and energy transformations as well as the resulting work it produces, it has practical applications in life for life is an active use of energy. First law is a conservation of energy which states that energy cannot be created or destroyed meaning that energy is already in existence and needs only to be applied to a system, example a human system, in various forms to benefit life. The second law states that in a natural process there is a direction from which the conservation follows and this is usually to a more disordered state (entropy). The third law just simply states that if absolute zero is reached then entropy will be zero, but such is an impossible occurrence.
October 1, 2003. Retrieved December 3, 2007
York: John Wiley and Sons, Inc., 1998.
Addison-Wesley Publishing Company, Inc., 1996.