where ln(2) is the conversion factor from base 2 of Shannon entropy to the natural base e of physical entropy. "N h" is the amount of information in bits needed to describe the state of a physical system with entropy "S". Landauer's principle demonstrates the reality of this by stating the minimum energy "E" required (and therefore heat "Q" generated) by an ideally efficient memory change or logic operation by irreversibly erasing or merging "N h" bits of information will be "S" times the temperature which is