You can show that
log_a(x) = ln(x) / ln(a)
So a logarithmic expression in any base can be rewritten using the natural log. The natural of has some advantages (it’s very easy to do calculus with), so it’s the most commonly used.
But it’s not true that other bases are never used. The base-2 log is used for half-lives in physics and doubling times in biology, the base-10 log comes up in audio and electronics (decibels), geophysics (Richter scale), and chemistry (pH), and the base 100 logarithm is used in astrophysics (stellar magnitudes).
Latest Answers