While a map flipped Captain Jack Sparrow’s world upside down in the Pirates of Caribbean, three scientists in Paris accidentally figured a way to make a toy boat float upside down, according to a paper published in the journal Nature.
The trick, behind what seems to be an optical illusion, is vibrations. One of the proven ways to make a liquid float is to shake it thoroughly. With the right kind of vibrations certain kinds of liquids can support layers of air. Air bubbles can sink to the bottom while the heavier liquid floats up.
The scientists Benjamin Apffel, Filip Novkoski Antonin Eddi and Emmanuel Fort found that vibrations inhibit the water to collapse to the bottom, instead it rests on a cushion of air. In short, a column of air is sandwiched between the bottom the container and the floating liquid.
In this particular experiment, the scientists took advantage of this phenomenon and found that objects in this layer of air experience an ‘antigravity’ effect. They suspended small boats in layers of glycerin and silicon oil.
While a number of physical factors are working in tandem, the external vibrations keeps them in delicate balance.
This phenomenon can be practically applied to separate liquid wastes, pollutants from water and mineral processing.