Question

Entropy used to calculate energy?

Answer 1

I'm currently reading an online article, and below is a quote from that article:

The thermodynamic entropy to change nnmemory cells within mm states is ΔS=kBln(mn)ΔS=kBln⁡(mn), where kBkB is the Boltzmann constant. From the second law of thermodynamics, ΔS=ΔQTΔS=ΔQT, where ΔQΔQ is the energy spent and TT is the temperature. So the energy required to write information into one binary memory bit is Ebit=kBTln2Ebit=kBTln⁡2.

But from what I've learned, QQ is heat transfer, not 'energy spent'. Why is it possible to use those 2 interchangeably, if it's possible

Answer 2

Entropy, the measure of a system's thermal energy per unit temperature that is unavailable for doing useful work. Because work is obtained from ordered molecular motion, the amount of entropy is also a measure of the molecular disorder, or randomness, of a system.