When a fluid is in motion, it must move in such a way that mass is conserved. To see how mass conservation places restrictions on the velocity field, consider the steady flow of fluid through a duct ...

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 ...