If space is a canvas, then brushstrokes cannot be infinitely thin. There's a tiniest segment, shorter than which there's no point in measuring. This quantum 'graininess' alters the geometry itself: the motion of galaxies and the growth of large-scale structures bear its mark.
Scientists replaced the mysterious dark energy with such a correction and derived an equation for the expansion of the Universe. The model was compared with data: supernova supernovae (the Nobel triumph of Adam Riess) and the echo of the Big Bang.
This quantum picture is not inferior to the standard model, and in a number of tests even outperforms it. It seems that dark energy is not a new substance, but a shadow of the quantum world cast on cosmic scales.
A ruler that never shows less than a millimeter is the essence of the uncertainty principle with a minimum length: it's impossible to measure distance with infinite precision.