entropy

[ en-truh-pee ]

noun

1. Thermodynamics.
   1. (on a macroscopic scale) a function of thermodynamic variables, as temperature, pressure, or composition, and differing from energy in that energy is the ability to do work and entropy is a measure of how much energy is not available. The less work that is produced, the greater the entropy, so when a closed system is void of energy, the result is maximum entropy.
   2. (in statistical mechanics) a measure of the randomness of the microscopic constituents of a thermodynamic system. : S
2. (in data transmission and information theory) a measure of the loss of information in a transmitted signal or message.
3. (in cosmology) a hypothetical tendency for the universe to attain a state of maximum homogeneity in which all matter is at a uniform temperature heat death.
4. a state of disorder, or a tendency toward such a state; chaos.
5. a doctrine of inevitable social decline and degeneration.

entropy

/ ˈɛntrəpɪ /

noun

1. a thermodynamic quantity that changes in a reversible process by an amount equal to the heat absorbed or emitted divided by the thermodynamic temperature. It is measured in joules per kelvin S See also law of thermodynamics
2. a statistical measure of the disorder of a closed system expressed by S = k log P + c where P is the probability that a particular state of the system exists, k is the Boltzmann constant, and c is another constant
3. lack of pattern or organization; disorder
4. a measure of the efficiency of a system, such as a code or language, in transmitting information

entropy

/ ĕn′trə-pē /

1. A measure of the amount of energy in a physical system not available to do work. As a physical system becomes more disordered, and its energy becomes more evenly distributed, that energy becomes less able to do work. For example, a car rolling along a road has kinetic energy that could do work (by carrying or colliding with something, for example); as friction slows it down and its energy is distributed to its surroundings as heat, it loses this ability. The amount of entropy is often thought of as the amount of disorder in a system.
2. See also heat death

entropy

1. A measure of the disorder of any system, or of the unavailability of its heat energy for work. One way of stating the second law of thermodynamics — the principle that heat will not flow from a cold to a hot object spontaneously — is to say that the entropy of an isolated system can, at best, remain the same and will increase for most systems. Thus, the overall disorder of an isolated system must increase.

Notes

Entropy is often used loosely to refer to the breakdown or disorganization of any system: “The committee meeting did nothing but increase the entropy.”

In the nineteenth century, a popular scientific notion suggested that entropy was gradually increasing, and therefore the universe was running down and eventually all motion would cease. When people realized that this would not happen for billions of years, if it happened at all, concern about this notion generally disappeared.

Other Words From

• en·tro·pic [en-, troh, -pik, -, trop, -ik], adjective

Word History and Origins

Origin of entropy¹

First recorded in 1865; from German Entropie; from en- ² + trop(o)- + -y ¹

Word History and Origins

Origin of entropy¹

C19: from en- ² + -trope

Example Sentences

“In some sense, it feels better to believe that there’s a secret society controlling everything than believing that entropy and chaos rule.”

From Los Angeles Times

The more he fumbled for answers, the more overwhelmed he became by entropy and uncertainty.

From Los Angeles Times

The amount of entropy was measured by a second LLM that focused on the meaning and nuance of the generated responses, rather than just the words used.

From Science Magazine

In this case, while the answers all used different vocabulary, their meanings are roughly similar—earning them a low semantic entropy score, which indicates the model’s response is likely to be reliable.

From Science Magazine

Responses to the same query that contained vastly different meanings earned high entropy scores, signaling possible confabulations.

From Science Magazine