# Foundation of Landauer's principle [duplicate]

I have asked this on CS subsite but since there was no reply yet and the question is also somewhat related to physics, I think it will be appropriate to post here as well.

Landauer's principle states the minimum possible amount of energy required to erase one bit of information is $k T \ln 2$

How is this formula found? In terms of energy and memory unit, what is the processing cost per bit for normal and reverse operations respectively?

The simple answer would be: consider a physical system that can be in two states. Its thermodynamic entropy is $k_B \log(2)$ due to this. When you erase the bit, then you have a definite microstate and the entropy is zero. Since entropy cannot decrease it has to go somewhere, and this means it needs to be transferred to the environment that has temperature $T$, giving us a cost $k_B T \log(2)$.