It is the result of a phenomenon dubbed the Cheerios effect. (Cheerios is a brand breakfast cereal).
Liquids have surface tension which makes the surface act like a membrane. When a buoyant object is placed in the liquid, its surface caves in slightly, causing a depression.
When you place a single Cheerio in a bowl of milk, the milk’s surface dips slightly under its weight. When you add more pieces of the same density, they form their own dimples. At the same time, they gravitate towards the first Cheerio, thereby clumping together. Similarly, they cling to the walls of the bowl. The same effect governs the behaviour of fuzzy bubbles on the surface of soft drinks.
The Cheerios effect is being used by scientists to explain the structure of large clusters of galaxies and stars in the universe that cling together, leaving vast amounts of empty space between them.
Picture Credit : Google
