A century after Albert Einstein said we would never be able to observe the instantaneous velocity of tiny particles as they randomly shake and shimmy (in so-called Brownian motion), physicist Mark ...

Figure 1: Schematic characteristic timescales of Brownian motion in different regimes. Figure 2: Schematic of the experimental set-up and upconversion luminescence measurements of the NaYF ...

A streamline is a line that is tangential to the instantaneous velocity direction (velocity is a vector, and it has a magnitude and a direction). To visualize this in a flow, we could imagine the ...