So apparently the [Krylov-Bogoliubov theorem][1] says that every continuous function $f:X\to X$ on a compact metrizable space $X$ has an invariant probability measure $\mu$. Of course, if $X$ is just a single point then there's only one such $\mu$. Also, if $f$ is constant. So assume $X$ is the Cantor space $\{0,1\}^{\mathbb N}$, or the unit interval $[0,1]$, and $f$ is invertible. >Must there be uncountably many such $\mu$? Must there be an uncountable family of mutually singular $\mu$'s? [1]: https://en.wikipedia.org/wiki/Krylov%E2%80%93Bogolyubov_theorem