Just what exactly is a champagne bubble? You might have thought that the effervescence of champagne was merely an enticing visual and audible sensation experienced just before bringing the flute to your lips, but from a purely scientific perspective, the entire complexity of fluid mechanics is expressed in these few centilitres of sparkling wine. An odyssey of fine beads of carbon dioxide magnified by the breathtaking images of Gérard Liger’s high-speed camera, transforming science into graphic art of rare grace.
You might be fooled into thinking you were looking at pictures of spinning galaxies or distant nebulae captured by the Hubble Space Telescope! Yet this universe, which draws heavily on chaos theory with its multiple and complex parameters, lies within a champagne flute that we clink together to add sparkle to an occasion. This ballet of crystal pearls rising in columns before releasing their tangy flavors on the surface, is Gérard Liger-Belair’s field of expertise. The 47-year-old physicist who heads the “Effervescence, Champagne and Applications” team affiliated with the University of Reims, is the only researcher in the world who specialises in the champagne bubble. In top scientific journals for the last fifteen years he has been publishing the results of his research on the physico-chemical processes in play from the point where bubbles begin to form until they burst onto the surface.
He grew up in Versailles and initially wanted to become an oceanographer until a diving accident put an end to this project, forcing him to redirect his scientific career path. A passion for photography drew Gerard Liger-Belair to start exploring the dynamics of bubbles in their flow field through images, using glasses of lemonade or even beer when money was tight. « For my thesis, I contacted the two major producers of fizz : Coca-Cola and Moët & Chandon and the Champagne House was the first to reply! », he explains. In 2001 he obtained a PhD from the University of Reims Champagne-Ardenne with commendations from the jury for his thesis on “A first approach of the physical processes behind the bubbling phenomena found in Champagne wines”.
Ever since then, champagne has been constantly flowing in his laboratory, analysed by high-resolution mass spectrometers and the most sophisticated cameras using laser tomography to capture the complexity of the swirling arrangement of the bubbles. « I never imagined that after all this time I would still experience the same passion and pleasure for exploring this universe, particularly through photography. I am amazed by the images we produce and these photos are extraordinary educational tools. The mathematical model equations of the bubble life cycle are of course essential, but the aesthetic aspect is also a common thread in my research » confides the physicist.
THE METHANE AND NITROGEN LAKES OF TITAN
With his initial publications, the champagne industry cast a somewhat suspicious eye on these experiments, fearing a demystification of champagne; “but pretty quickly the professionals realised the benefits of our research and also of our images, which add an extra dimension to the magic of champagne,” he explains. Gerard Liger-Belair’s team is credited with the discovery of the origin of the bubble. Contrary to popular belief, it is not only the imperfections of the glass that create the bubble, but above all the tiny cellulose fibres suspended in the air or left by a cloth that trap the carbon dioxide dissolved in the wine and release it in the form of bubbles. Therefore, the number and shape of the bubbles say much more about the glassware (shape and height of the glass) and external conditions such as pressure or temperature, than about the quality of the wine. And as it’s all about the speed with which the bubbles rise to the surface and burst, shooting their aromatic molecules towards our nostrils and taste buds like a spray of perfume, champagne should be poured slowly down the side of a tilted glass to preserve the CO2 – the fizz – as much as possible, for as long as possible. The team’s latest publication covered by the media is about the discovery of a “blue cloud” when opening a bottle at room temperature. The gas, at a pressure of nearly 8 bars, undergoes a violent decompression which causes its temperature to drop to -90°C. “The blue cloud is formed by the transformation of CO2 gas into minute particles of dry ice which then diffuse the ambient light. In terms of physics this cloud has the same origin as the blue colour of the sky,” explains the physicist.
And
because the laws of physics apply everywhere in the same way, the behaviour of
a gas is no different in a glass of champagne, in the oceans, in the Earth’s
atmosphere or the atmosphere of other planets in the solar system. The
research, observations, and mathematical models of the team from Reims tackle
more global issues such as the “fizzing” of the oceans and the
production of sea spray, which play a part in the complex chemistry of the
atmosphere and global climate balance. Or indeed, the causes of bubbling on the
surface of the methane and nitrogen lakes of Titan, one of Saturn’s moons, or
even the turbulence observed in Jupiter’s sky.
Back to Earth with a champagne enigma yet to be resolved by Gerard Liger-Belair : the phenomenon of gushing, which can
empty a bottle of much of its precious beverage as soon as the cork is popped.
A practical application which, no doubt, the entire
champagne industry is eagerly awaiting.
