> It feels intuitive that a thin fluid on a low-friction surface (like water) would spread out "as much as possible" given enough time. Most fluids do not beha

> It feels intuitive that a thin fluid on a low-friction surface (like water) would spread out "as much as possible" given enough time. Most fluids do not behave this way in most circumstances, because of surface tension, so it's really not intuitive. This experiments is one of the few ways you can get an accurate measurement. Many other fluids will either mix or end up as bubbles/blobs many orders of magnitude thicker than a molecule.