Watching fly-throughs of galaxy maps reminds me of shining a flashlight in a dusty room; the illuminated particles, each clinging on tight to its own little world of unfathomably many tiny creatures, dance chaotically on the dark undercurrents of air. By observing their Brownian motion, Einstein was able to deduce the atomic nature of the unseen medium.
A hundred years later, with galaxies suspended in spacetime, might we be able to do the same thing?