Hovering blue flames that flicker over bogs and marshes have inspired ghostly folktales for centuries. Known as “will-o’-the-wisp,” “jack-o’-lantern,” “corpse candle” and “ignis fatuus” (“foolish fire ...

At first glance, the soap foam appears to be quite simple: it is light, airy, and most often white. However, there is a great deal going on behind the scenes, with many tiny bubbles and a great amount ...