In the real wold, there is no such thing as a truly smooth surface. It’s possible in the mathematical world but as far as reality is concerned, no.
If you look closely enough, everything turns out to be made of distinct atoms (no smooth distributions). That’s actually where the quantum from quantum mechanics comes from, the fact that matter is quantized (comes in discrete quantities) rather than being continuous.
glass
lotus leaf
earth
“Earth, as a cosmic object is remarkably smooth; if you had a giant finger and rubbed it across Earth’s surface (oceans and all), Earth would feel as smooth as a cue ball. Expensive globes that portray raised portions of Earth’s landmasses to indicate mountain ranges depict a grossly exaggerated reality.”
– Neil deGrasse Tyson