Hundred year old bubble physics mystery solved
Bubbles in a liquid move upwards. Eg: carbon dioxide bubbles in a carbonated drink. But when a bubble is trapped in a narrow vertical column of liquid, it does not appear to move upwards. This has remained a mystery until now. Scientists at the Ecole Ploytechnique Federale de Lausanne (EPFL) have solved this mystery using a technique called ‘optical interference’. In this method, a light beam was incident on such a ‘trapped’ bubble and the nature of the reflected light was analysed to understand what’s happening. It was found that the thin film of liquid surrounding the bubble was causing it to rise very slowly that it almost appears static. This liquid film is only few nanometers thick. The study also found other properties of such bubbles like how heat application changes its shape. The removal of heat source allows the bubble to regain its original shape.