What does entropy measure?

Answer 1

Entropy is the measure of chaos or disorder in a closed system. For example: imagine an empty room with a single cup of tea (or coffee if you are American) on a table in the center of the room. Imagine that the beverage starts it's life at 373 degrees Kelvin (the boiling point of water) and the room is at 300 degrees Kelvin (approx room temperature). If you were to observed how ordered the energy in this room is the cup of tea/coffee would be a highly organized body of energy. This is easiest to imagine if you try and see the room through a thermal imaging camera, the cup would appear very hot while the room would remain cold in comparison. Eventually however (as you may know from experience) leaving a hot drink out for long enough causes it to go cold and therefore undrinkable, if we were to watch this happen through our thermal imaging camera the temperature of the cup would decrease while the temperature of the room would increase very slightly until both are at the same level. This is because energy always moves from a more energetic body into a less energetic one and we rarely observe it going the other way round. It is possible that all the energy from the room could be transfered into the cup all of a sudden and make it white hot while the room freezes but it is so unlikely that we do not expect it to happen.

In short entropy is a measure of the organization of energy in a closed system. If one were to observe the Earth you would see that entropy appears to be moving in reverse, energy is always being more organized. If you take into account the bigger picture that the Sun is the body providing that energy and is, in turn becoming more disordered, we see that eventually entropy always has it's way. You can liken entropy to the owner of a casino, he might get the odd winner in which case entropy is reversed, but in the end there are more losers than winners and so ultimately entropy stays in business. On a grand scale the universe is one such closed system and as Rudolf Clausius initially discovered, the rate of change in entropy in the universe is always higher than 0, so it never goes backwards overall, therefore eventually the universe will be so disordered that no energy can be used or collected without expending energy one doesn't have. This is known as the heat death of the universe and the concept can be summed up with the formula

Δsuniverse > 0 .

In simple terms, entropy is the measure of the level of disorder in a closed but changing system, a system in which energy can only be transferred in one direction from an ordered state to a disordered state. Higher the entropy, higher the disorder and lower the availability of the system's energy to do useful work. Although the concept of entropy originated in thermodynamics (as the 2nd law) and statistical mechanics, it has found applications myriad of subjects such as communications, economics, information science and technology, linguistics, music. In day-to-day life it manifests in the state of chaos in a household or office when effort is not made to keep things in order Entropy is the explanation that a system goes towards a state of disorder.

Answer 2

Entropy is the inclination for things to increase their level of disorder.

eg. If you buy a puzzle in a box and you shake it really hard the pieces become more disorganized, near fall back into their proper place.

APEX ANSWER: Entropy measures the disorder in a system

Answer 3

entropy measures the disorder in a system

-APEX

Answer 4

Entropy measures the amount of disorder or randomness in a system. In thermodynamics, it is a measure of the number of possible microscopic configurations that a system can have at a given macroscopic state. In information theory, it quantifies the average level of uncertainty or surprise in a set of data.

Answer 5

The importance of discussing and understanding the meaning of entropy and Entropy Theory is no less than making sense of how the Universe is organized and whether or not it started with a Big Bang or is, perhaps, after all, in fact, a steady state universe of unknowable or at least unknown origin. Entropy theory is based on the observations that everything seems to be in a state of decay--that metal will rust and crumble, buildings and bridges will eventually return to dust and that the stars will all burn out and the universe will just keep getting colder and colder--that this is a one way street, and it is a downhill trip that is inevitable. However, for the purpose of discussion, let me submit that this is only one half of the equation--half of the action--half of the drive of nature. Consider this, for anything that you can think of that might be in a position where it can decay or fall apart, didn't it first have to be built up or be put together or be caused to be organized in the first place from random chaotic elements of nature? Therefore, any decaying or falling apart is just returning to its original state of equilibrium. Build Up = Fall Down One example that has been used in the past to demonstrate the notion of a one way path of entropy toward dissipation and disorder is the action of the fragrance of perfume in a bottle. At first consideration it might seem that left to itself, open to the air in the room, the fragrance could only evaporate and spread out into the air, and could never just spontaneously return from the air back into the bottle. This example has actually been put forth by otherwise well thought of and respected "scientists." Do you see the obvious flaw in this argument? What about all the concerted and considerable effort that was put into the entire process of collecting, then forcefully concentrating, distilling and filling the bottles in the first place. A full bottle of perfume is in no way some original state of being, but rather a highly artificial and forcefully concentrated and stacked potential state that is very unnatural, like a wound spring. That is the other half of the equation that seems to have been overlooked in the old way of thinking of entropy as a downward trip into oblivion--from the "Big Bang" to the "Long Good-night." The Big Bang Theory-- that every gram of our physical universe came out of one very small, central location has never sat well with many prominent scientists, and it does defy our basic sense of logic. So, I welcome this as one part of the argument for a steady state, vacillating universe, where the elements are constantly coming together and falling apart at every level. -- James Aaron Nicholson

Answer 6

Entropy is involved with the second law of thermodynamics.

In short, it is an increase in two things within a given system.

1. increase in disorder

2. increase in the % of unusable energy

Answer 7

Heat energy available in a system but no transfer of heat.

(Another reply) There is no "simple definition"; the precise definition is based on advanced mathematics (a derivative, if I remember correctly). However, entropy is related to unusable energy. The Second Law of Thermodynamics can be stated in different ways; one way is to say that there are irreversible processes; another way is to say that entropy increases. Entropy is related to unusable energy, but it is not exactly the same, it doesn't even have the same units. Energy is measured in Joule, the unit for entropy is Joule x Kelvin.
It's the negative logarithm of the probability of the existing energy distribution.

(And that's the SIMPLE one.)

Answer 8

Entropy refers to a measurement used in thermodynamics. This measure is usually represented by an "S" and is usually used for measuring disorders.

Answer 9

the disorder or randomness of the particles of a system

Answer 10

Entropy define the state of disorder (big entropy) or order (low entropy).