Most researchers consider information entropy and thermodynamic entropy directly linked to the same concept, while others argue that they are distinct. Both expressions are mathematically similar. If W is the number of microstates that can yield a given macrostate, and each microstate has the same a priori probability, then that probability is p = 1 / W . The Shannon entropy (in nats) is: H = − − ∑ ∑ i = 1 W p i ln ⁡ ⁡ p i = ln ⁡ ⁡ W and if entropy is measured in units of k per nat, then the entropy is given by: H = k ln ⁡ ⁡ W which is the Boltzmann entropy formula, where k is the Boltzmann constant, which may be interpreted as the thermodynamic entropy per nat. Some authors argue for dropping the word entropy for the H function of information theory and using Shannon's other term, "uncertainty", instead.