The original version of this story appeared in Quanta Magazine.
Sip a glass of wine, and you will notice liquid continuously weeping down the wetted side of the glass. In 1855, James Thomson, brother of Lord Kelvin, explained in the Philosophical Magazine that these wine “tears” or “legs” result from the difference in surface tension between alcohol and water. “This fact affords an explanation of several very curious motions,” Thomson wrote. Little did he realize that the same effect, later named the Marangoni effect, might also shape how embryos develop.
In March, a group of biophysicists in France reported that the Marangoni effect is responsible