Energy & Green Tech

Non-noble catalyst for hydrogen production

Hydrogen is a promising future fuel—especially if produced from water—but the necessary noble metal catalysts are rare, expensive, and have insufficient reserves. But now, in a study recently published in Advanced Materials, ...

Computer Sciences

Observing time crystals on a quantum computer

When you hear the words "time crystal" you could be forgiven for imagining something fantastic like a magic crystal ball or a device for time travel. But time crystals are very real, although they are a bit like magic.

Engineering

3D-printed, ultra-strong and ductile alloys form nanostructures

Additive manufacturing techniques used to produce metal alloys have gained popularity due to their ability to be fabricated in complex shapes for use in various engineering applications. Yet the majority of studies conducted ...

Engineering

Machine learning unlocks secrets to advanced alloys

The concept of short-range order (SRO)—the arrangement of atoms over small distances—in metallic alloys has been underexplored in materials science and engineering. But the past decade has seen renewed interest in quantifying ...

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Entropy

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