Research published yesterday by scientists at the university of Liege in the New Journal of Physics (NJP) reveals for the first time how antibubbles form and move through a liquid.
Antibubbles are the exact opposite of bubbles and move down instead of up. Whereas a bubble is a thin flim of liquid in air and which encloses a pocket of air, an antibubble is a thin film of air made inside a liquid, enclosing a pocket of that liquid. Scientists have known about them for almost a century but why and how they form has been a mystery until now.
Dr Stéphane Dorbolo and colleagues at the university of Liège, in collaboration with the Collège de France, have proposed a mechanism which describes how antibubbles are made and also how they move through a liquid.
They observed antibubbles in a variety of liquids in the laboratory and made timed digital films of them; observing how they are created, how they move and also how they "die" when they burst.
Antibubbles can be created by pouring a liquid containing a "surfactant" - soapy water for example - onto an identical liquid.
According to the researchers, they form because a thin film of air is sometimes pulled down along with the liquid itself. This air film then separates two liquids with the same composition and so is called an antibubble, since a real bubble is a liquid film separating two regions of air.
Out of curiosity, the researchers also attempted to create antibubbles in Belgium's most famous export - beer. Apparently they thought that this would not be possible because you can not create antibubbles (or bubbles) in pure water, alcohol or oil.
However, they found that you can make antibubbles in beer because beer contains protein which makes it a surfactant just like dishwashing liquid.
"We have come up with a good model describing how they[antibubbles] form and move and have also learnt more about the type of liquids you can create them in,' said lead researcher Dr Stéphane Dorbolo.
We tried to create them in beer for fun, and didn't think it would be possible, but were amazed when we magaged to create giant antibubbles which lasted for almost two minutes and that moved around a glass of beer before bursting, he added.
One peculiar result of the antibubble phenomenon say the researchers is the 'jellyfish'. "We also found that when the antibubbles die, or burst, they morph into a form of structure which we have nicknamed the jellyfish form because it looks very like a jellyfish swimming through water. It slowly moves and fades away until it disappears altogether," concluded Dr. Dorbolo.
Full findings can be found online New Journal of Physics, published jointly by the Institute of Physics and Deutsche Physikalische Gesellschaft (DPG).