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What is entropy? The most way to explain it is to say that it describes the natural tendency of the universe to fall apart into disorder. A well known illustration is the messy room concept. You know that you need to constantly work at keeping your room clean and well arranged. However, you know that if you don’t keep up with the routine the room will gradually return to its messy state.
However, entropy has other meanings and applications as well. It can also mean the state of a thermodynamic process. Essentially, this is the inertia that makes a thermodynamic process more likely to occur. Certain reactions and processes occur more often because the larger value of entropy in the system of the reaction. Any reaction that releases energy can be considered to experience an increase in its entropy.
Like pushing a boulder down a hill thermodynamic reactions will continue until it reaching equilibrium a barrier that prevents the reaction from continuing. Entropy is an aspect of the reaction that can be used to measure this.
Entropy is also seen as “times arrow” you can use it to see if a certain substance or system has undergone a change that releases energy. An important example of this concept is the universe itself. While matter can be neither created or destroyed due to the law of conservation, we know that the amount of usable energy released in a reaction will steadily decrease. This means that one day the universe will run out of usable energy and its entropy will increase to the point that means the “death” of the universe.
Entropy is something that has many meanings and applications. It also is very hard to directly measure. One reason is that it involves several quantities such as kinetic and potential energy, temperature, work and force. Entropy is a value that can be seen to embody all these quantities. So it can be seen as a derived value that relies on all these values.
In the end entropy is important because it helps us to understand how thermodynamics works whether it is on the chemical or cosmic level. It can mean the tendency of the cosmos to fall into disorder, be a measurement of thermodynamic process or reaction, or simply a measure of the energy available for work or becomes heat.
If you enjoyed this article there are others on Universe today that you will like to read. There is an interesting article about Entropy and the second law of thermodynamics. There is also an interesting article about why time might go in one direction.
There are also some great resources online. You can check out the Principia Cybernetica site. It has a very concise explanation of entropy. You can also look at the Georgia State astrophysics web page.
You can also check Astronomy Cast. Episode 139 talks about energy levels.