The Second Law of Thermodynamics

In a closed system, entropy will always increase over time.

Let's break down that sentence. First, a closed system. There is some controversy about the definition of a closed system among scientists, but for our purposes, let's say that a closed system is any system of interacting things that you define as such, that has no interaction with other things, outside itself. So the solar system is a closed system that contains the planet Earth. Not much, except for gravity and the occasional asteroid, interacts with the sun, the Earth, and the other planets in our solar system. It is pretty much a closed system. The Earth itself, however, would be considered an open system because the sun greatly affects it, yet is outside of it. Here on this planet, we can define smaller closed systems. Never perfectly closed, but enough so for a discussion of thermodynamics. An egg, an engine, a cup of hot coffee, a car: A closed system is a system that can operate in and of itself, without any outside energy source. You may say, "Well, you have to put gasoline in a car, and that's from the outside." Yes, it's true, but I'm speaking about once the gas is in the car; the car becomes a closed system. It no longer needs to exchange energy or matter with anything outside of itself to function. It is then closed. So, back to the second law.

In a closed system, entropy will always increase over time. What is entropyl Entropy is often equated with chaos. Entropy is not chaos; chaos is often the result of entropy. Entropy, quite literally, is waste heat. Heat is a form of energy, and entropy is waste heat. Waste heat is heat that is emitted into the universe, never to be used in the closed system that it was emitted from again. Entropy is just waste heat energy.

So.

In a closed system, entropy, or waste heat, always increases over time. Always increases over time. Always. No matter what the energy system, over time, waste heat will escape into the atmosphere, never to be captured again.

("Seriously, I just want to do a couple of funny characters.")

Here's an easy example of the second law: I make an Irish coffee. I get distracted by a friend asking me about improv and forget I had an Irish coffee sitting on the bar. The Irish coffee, previously hot, begins to cool. It does this on its own. Entropy, or waste heat, emits from the hot coffee/whiskey pleasure into the atmosphere, never to be recaptured by that particular Irish coffee again, and thereby cooling the Irish coffee. The coffee could be given energy (heat) again from an outside source, but the original heat energy was dis­persed, at random, into the universe as waste heat. That's another way of stating the second law:

Things tend toward cool. A glass of water doesn't just heat up on its own. It needs an outside source to add energy to it, and if left on its own it will tend toward cool. The biggest example of this in our world would be the sun, which will tend toward cool and burn out in a few billion years. We on Earth live off the entropy of the sun.

Here's a more immediate example of the second law: I finish my fourth single malt scotch at a bar and leave the glass on a table. In a stupor, I get up to leave and accidentally knock the glass off the table. My hand and gravity are the forces that combine to send the glass to the floor. The glass breaks. So what happened? The force of impact broke some of the molecular bonds of the glass, causing it to break. When those bonds are broken, the heat energy that used to hold the glass together is released in the form of waste heat. That waste heat energy is dispersed into the atmosphere, never to be recaptured by the glass. As a result, the glass remains broken. This is why entropy is equated with chaos. The result of the release of waste heat in the scotch glass causes disorder for the glass, or chaos, and the energy necessary to have the glass again be the glass it once was, is gone forever. Yes, you could glue the pieces back together to restore the glass, but you are really adding another energy to create mended glass, not recreating the original.

This is what things tend toward—order to disorder—because of the second law of thermodynamics. Broken glass on a floor does not spontaneously become a scotch glass, but a scotch glass is just waiting for the release of energy necessary to become broken. Everything on our planet tends toward disorder, including you. We fight the second law every day by remaining alive. No matter what we do, we tend toward disorder as we grow older and older. The second law is why car tires wear out, cigarettes burn, and dead poo­dles decompose.

This is also why a perpetual motion machine can never work. Throughout history, many people have tried to create a machine that, once set in motion, will eternally function on its own without any additional energy input. This machine is impossible, because the parts of the machine will interact with one another, or the molecules in the air, creating friction. Friction is a form of waste heat dispersed from the machine, never to be recaptured by it. A perpetual motion machine will eventually stop working, which is another definition for the second law.

Of the first law, as I mentioned earlier, people often say, "You can't win." Of the second law, people say, "You can't even break even." No matter what the system, a percentage of energy will always be given off, tending toward that system's disorder. It takes energy to maintain order, but the universe doesn't prefer it. An ice cream shop left empty and unattended for 100 years will become disordered. A cigarette will burn and never become that cigarette again, a universe will cool and reach equilibrium, and a dead poodle will decompose at the bottom of cliff, never to recapture its lost energy and become that poodle again. The second law.

Дата добавления: 2015-07-08