Without the application of external energy, the entropy of a system will always increase. This is the heart of the second law of thermodynamics. However, contrary to how it is often stated the application of energy does not magically reduce the entropy of a system. The simple fact of the matter is that the entropy of the energy being applied to the system determines how the energy affects the entropy of the system.
What is energy?
The basic scientific definition of energy is: “the ability to do work.” Energy is what allows everything in the universe to move and do things. We take in energy from the food we eat and use it to run our bodies. Energy comes in many forms: mechanical, kinetic, Thermal, chemical, electrical, and radiant. There are ways of turning all of these forms of energy into useful work. It is also energy that is responsible for mass, and this allows us to control our motion.
What is entropy?
In classical thermodynamics, entropy is often described as a measure of disorder. Now entropy and disorder are related, but they are not the same thing. This is because while an increase in the disorder of the system increases its entropy, there are other factors involved. In physics, entropy is more accurately defined as a measure of how spread out or dispersed energy becomes at a specific temperature.
In statistical mechanics, entropy is precisely defined by the Boltzmann formula: S = k ln Ω, where S is entropy, k is the Boltzmann constant and Ω is the number of microstates. Microstates are the specific microscopic configurations of particles that correspond to the macroscopic state of the system. High entropy means there are many ways to arrange the particles without changing the overall look of the system.
Now the rest of the relationship between disorder and entropy is through the size of the system. This is because you can double the number the microstates of the system, simply by doubling its size. This does not make your system anymore disorderly just bigger. As a result, the disorder of a system results from dividing the number of equivalent states by the size of the system.
The number one misconception about how the application of energy affects entropy.
The most common misconception about how the application of energy affects entropy is that the application of energy reduces entropy. Now when energy is applied to a system in a relatively low entropy manner, then locally entropy is reduced within that system. However, the resulting heat produced by the process increases the entropy of the environment. Consequently, it is not a free lunch, but the local reduction in entropy Is paid for by a general entropy increase.
A common misconception that some people seem to have is that just adding energy magically reduces the entropy of the system to which it is applied. Now this may just be the way they word their comments, but they come across as taking this position. The actual answer Is that the applied energy moves the entropy of the system towards the entropy of its application. This means that if the energy is applied with lower entropy than that of the system, it will reduce the system’s entropy. However, if the energy is applied with higher entropy than that of the system, it will increase the system’s entropy.
What really happens when energy is applied to a system.
When energy is applied to a system, the number of equivalent states of the system moves towards that of the applied energy. When the applied energy has lower entropy than the system, the system’s entropy is reduced. However, high entropy heat energy is produced raising the entropy of the environment. When the applied energy has higher entropy than the system, the system’s entropy is increased and the high entropy heat energy produced still raises the entropy of the environment. This waste heat also ensures that no process can be 100% efficient in its use of energy. Some energy will always be lost to heat raising the entropy of the environment.
The mathematics of entropy and applied energy.
The mathematics of the effect that applied energy has on entropy is actually quite simple. One reason is that statistically entropy is related to the number of equivalent states that the system can have. In chemical reactions the change in entropy is related to the heat energy used divided by the temperature.
Furthermore, since the number of equivalent states of the system moves towards the number of equivalent states of the applied energy, the change in entropy of the system results from the differences of the number of equivalent states of the system and the applied energy. This means that the application of energy with a lower entropy than that of the system will reduce the system’s entropy. However, the application of energy with a higher entropy than that of the system will increase the system’s entropy.
The general principle of entropy and applied energy.
Put as simply as possible, the general principle of entropy and applied energy is that you can locally reduce entropy, but it requires applying energy to that local system with less entropy than that of the system. Commonly called work, the tradeoff is that in the process you could use high entropy energy, that increases the entropy of the environment. On the flip side applying energy to a system with higher entropy than that of the system increases the entropy of both the system and the environment.
Explains the difference between construction work and a bomb.
The perfect example for properly understanding how the entropy of applied energy affects the entropy of a system, is the difference between construction work and a bomb. Construction work and a bomb can both apply the same amount of energy. However, construction work is extremely low entropy because it is directed towards a particular purpose, but a bomb is extremely high entropy that gets applied randomly, Consequently, construction work builds while, a bomb destroys.
Conclusion
When energy is applied to a system the number of equivalent states of that system goes towards that of the applied energy. If the reduction of entropy just required a lot of energy as is sometimes implied, then the atomic bombs dropped on Hirashima and Nagasaki should have caused new buildings to suddenly appear fully constructed. However, in reality, they totally destroyed large portions of the cities. Bathing yourself in large amounts of ionizing radiation should improve your health, however if it did not instantly kill you, you would probably die slowly from cancer.
This also poses a problem for the idea of abiogenesis. You cannot simply claim that because the Earth gets lots of energy from the sun, that abiogenesis is somehow thermodynamically possible. To legitimately make such a case, you would need to present and mechanism for specifically taking that solar radiation and converting it into the low entropy construction energy necessary to produce a living cell. The problem for abiogenesis is that the only such mechanism known, exists exclusively within a living cell. In the absence of such a mechanism the probability against abiogenesis occurring exceeds the number of possible events in the history of the universe by hundreds of orders if not billions of orders of magnitude. Unfortunately, this is a problem that is frequently ignored by those insisting on a totally naturalistic origin for life.
