ANATOMY OF A SNEEZE With a high-speed camera, MIT’s Lydia Bourouiba watches the explosive fluid dynamics of sneezing. Capturing around a million frames per second, her cameras let her measure the size and speed of large saliva and mucus droplets...
CONTINENTAL CONNECTION The seaway separating North and South America, illustrated as it was 35 million years ago (left), may have closed more than 13 million years ago and about 10 million years earlier than previously thought, new evidence suggests. Today, Central America separates the modern Atlantic and Pacific oceans (right).
Why some liquids are 'fragile' and others are 'strong'
A levitated drop within the WU-BESL. Electrodes above and below the sample charge its surface by induction, and it rises in the evacuated chamber, hoisted by electrostatic attraction. This ‘containerless’ technique allows the drop to solidify without crystallizing.
What you see here is a viscous drop falling into a less viscous fluid. Shear forces between the drop and the surrounding fluid cause the drop to quickly deform into a shape like an upside-down mushroom as it descends. The cap forms a vortex ring that curls the viscous fluid back on itself. As it does, that motion compresses the viscous sheet, causing it to wrinkle, as seen in the close-up in the bottom animation. Check out the full video here. (Image credit: E. Q. Li et al., source)