Label the different states a thermodynamic system can be in by <math>i=1,2,3\ldots N</math>. If the probability of finding the system in state i is <math>p_i</math>, the entropy is
+
Label the different states a thermodynamic system can be in by <math>i=1,2,3\ldots N</math>. If the probability of finding the system in state i is <math>p_i</math>, then the entropy is
<math>
<math>
−
S=-k_B \sum_i^N p_i \log p_i
+
S=-k_B \sum_{i=1}^N p_i \log p_i
</math>
</math>
−
This definition is closely related to ideas in [[information theory]], where the definition of information content is very similar to the definition of entropy.
+
where <math>k_B</math> is the Bolzmann constant. This definition is closely related to ideas in [[information theory]], where the definition of information content is very similar to the definition of entropy.