Understanding the thermodynamic cost of timekeeping

Clocks are essential building blocks of modern technology, from computers to GPS receivers. They are also essentially engines, irreversibly consuming resources in order to generate accurate ticks. But what resources have ...

Simple entropies for complicated molecules

Chemists of the University of Bonn developed a computational tool for the analysis of conformational entropies of flexible molecules. Their method enables the thermodynamic investigation of complicated chemical systems by ...

Scientists investigate 3-D-printed high-entropy alloys

Scientists from the Skoltech Center for Design, Manufacturing and Materials (CDMM) and the Institute for Metals Superplasticity Problems (IMSP RAS) have studied the fatigue behavior of additive-manufactured high-entropy alloys ...

Aging, entropy and waste: Flushing out damaged cells

One theory of aging invokes the Second Law of Thermodynamics and suggests that in the long-term, the heat energy generated by metabolic changes causes damage to living systems that accumulates as repair mechanisms cannot ...

page 1 from 12


Entropy is a concept applied across physics, information theory, mathematics and other branches of science and engineering. The following definition is shared across all these fields:

where S is the conventional symbol for entropy. The sum runs over all microstates consistent with the given macrostate and is the probability of the ith microstate. The constant of proportionality k depends on what units are chosen to measure S. When SI units are chosen, we have k = kB = Boltzmann's constant = 1.38066×10−23 J K−1. If units of bits are chosen, then k = 1/ln(2) so that .

Entropy is central to the second law of thermodynamics. The second law in conjunction with the fundamental thermodynamic relation places limits on a system's ability to do useful work.

The second law can also be used to predict whether a physical process will proceed spontaneously. Spontaneous changes in isolated systems occur with an increase in entropy.

The word "entropy" is derived from the Greek εντροπία "a turning towards" (εν- "in" + τροπή "a turning").

This text uses material from Wikipedia, licensed under CC BY-SA