Champagne Physics and More
Dr. Patrick Hunt, Stanford University
a) Image courtesy iTune/iPhone apps b) Champagne bubble mousse (photo Quinn Dombrowski, 2008, courtesy of Creative Commons share alike 2.0)
Staring at the bubbles in a champagne glass isn’t necessarily a sign of being under the influence. Poets, however inspired, have described champagne bubbles metaphorically as cabuchon gold or pearl gems, as seen in the above image. Nor is the physics of champagne merely a guaranteed interesting table conversation topic. Not to be outdone by poets, physicists have studied the bubbles in champagne and sparkling wine for more than a century and a half, where the behavior of carbon dioxide follows a regular pattern of gases in a liquid. Who hasn’t watched the bubbles rise in golden chains though a flute, increasing in size as they rise to the surface, wondering why the bubbles grow as they ascend? That’s one effect that observing champagne seems to have on both poets and physicists.
One scientist in particular appears to have studied these kind of questions and their history more assiduously than almost anyone else, possibly suggesting not only that he is a connoisseur of champagne but one of its most informed consumers. Gerard Liger-Belair at the Université de Reims in the heart of France’s champagne country is just that highly-regarded bubbles expert, judging by only a selection of his publications below. Many people assume that champagne was “discovered” in the late 17th century and perfected by the Abbey of Hautvillers monk cellar master Dom Pierre Pérignon sometime after 1670, but it was more likely that he merely began to tame the rogue bubbles. The Church wanted to rein in the effervescence in what was called the "Devil's Wine" because so many bottles exploded in their monastic cellars in the region, and Dom Pérignon was tasked to reduce efferevescence. It was mostly a physics problem whose solutions had to be practical. As Liger-Belair relates in his fascinating book Uncorked: The Science of Champagne (Princeton 2004), a famous anecdote is that Dom Pérignon reputedly exclaimed, "Come quickly, brothers, I am drinking stars!" True story or not, another poetic metaphor was born. But at first there were more negatives than positives in the up-and-down story of champagne. No less informative on the fluctuations of champagne, including gutsy wartime survival of heroic champagnistes, is Don and Petie Kladstrup’s excellent book, Champagne: How the World's Most Glamorous Wine Triumphed Over War and Hard Times (Harper, 2006). One Kladstrup factoid reinforcing the danger of exploding bottles was the requisite iron grill face mask worn on early cellar visits.
Robert Boyle (1627-91) (public domain image)
Boyle's Law and Champagne
Stronger bottles - including thicker glass and a deep punt "dimple" in the base - and more reliable ways of keeping the cork secure, eventually a wire cage called a muselet, were two evolving fixes. Comparing the expanded wider-base cork popped from a bottle of champagne or sparkling wine to the straight cylindrical cork of normal wine (where it has to be pulled), this difference shows another solution applied to this higher pressure fermentation product known as champagne. These physics fixes didn't happen overnight but rather over decades and even at least a century between the late 17th to 18th centuries. It must not be a coincidence that these pragmatic improvements happened during the Enlightenment when burgeoning science also came to grips with Boyle's Law on the behavior of gases and Lavoisier's later identification of oxygen. How timely is it that Robert Boyle published his law in 1662, the same year other champagne milestones occurred, discussed below? Boyle's Law essentially states that the relationship between the absolute pressure and volume of a gas is inversely proportional if the temperature is kept at a constant within a closed system. Sounds like either Boyle was studying champagne, or others applied his published experiments to champagne! This is exactly the problem champagnistes were encountering with fluctuating temperature between winter to spring in Champagne's refermentation cycle. So there is a directly proportional relationship between Boyle's Law and champagne!
Memorial to Dom Pérignon at Moët & Chandon, Epernay (photo P. Hunt 2010)
I was in Épernay a few months ago at Moët & Chandon in conversation with the champagne house's communications department representative Stephan Jacquemin. We were musing about the earliest history of sparkling wine, possibly long before Dom Pérignon.  Many have suggested the Romans had a natural sparkling wine with inevitable but unpredictable carbonation. If true and Roman vintners ever achieved something close to a tight seal for even a short period, the carbonation pressure must have shattered more than a few clay amphorae. Although much debated and not necessarily desirable or sought after, some evidence for this Roman antecedent is often hinted in the Latin word spumatio and its source verb spumo,  speculating that Italian spumante wine derives from a much older Roman tradition. But it is important to remember that sparkling wine would not have necessarily been a contrived effort but instead merely a natural by-product of carbonation from yeast. As Jancis Robinson clearly explains in The Oxford Companion to Wine, “bubbles form because a certain amount of carbon dioxide has been held under pressure dissolved in the wine until the bottle is unstoppered, in which case the wine is transformed from the stable to the meta-stable state.”  As mentioned, the natural yeast’s carbonation produced undesirable results for centuries, including bursting bottles, since the cold French winters halted fermentation and warmer spring kick-started refermentation again. It was touch-and-go until stronger bottles were specially made to withstand the internal pressure, as already discussed above. That the Romans were in and around Reims is clear from the chalk mines that now comprise some of Pommery’s and others’ champagne caves converted from chalk pits called crayères around 30 meters (about 100 feet) underground.  I visited these a decade ago and noted the abundant intact Roman artifacts on display in the adjacent mines sharing space with champagne.
Widow Clicquot’s Legacy
As tastes changed after the sparkling wine from the region of Champagne was introduced at the Louis XIV's Versailles court by Marquis de Sillery, it was the exiled Marquis Charles de St-Évremond who seems to have presented champagne to London around 1662. Christopher Merret had even read a paper in 1662 before the Royal Society in London about how to make sparkling wine. Since our London-based historian daughter had introduced us to Tilar Mazzeo’s recent book The Widow Clicquot: The Story of a Champagne Empire and the Woman Who Ruled It (Harper, 2008), our family duly trooped in pilgrimage through the countryside to Madame Clicquot’s neo-Gothic chateau in Boursault overlooking the Marne, where she retired after almost single-handedly building the supply and demand global champagne market by 1840, making it an elegant commodity by her merchandising genius. Thanks to Veuve (“Widow”) Clicquot (née Barbe Nicole Ponsardin), champagne today is a status beverage whose orderly bubbles confer even more elegance on grand ladies, especially the ambience of an excellent champagne. The international LVMH (Moët Hennessy - Louis Vuitton S. A.) Group is well-represented not only in Épernay but anywhere wealth and celebration meet. Although LVMH has a stable of thoroughbred perfume and fashion houses like Louis Vuitton, Fendi, Dior, Givenchy, and even a 20% stake in Hermes, it controls many of the world’s best names in the world of wine and spirits. In addition to Hennessy cognac, the sauternes Chateau d’Yquem is one of its holdings; Dom Pérignon, Moët et Chandon, Veuve Clicquot and Krug champagnes are others.
Chateau Boursault – Madame Clicquot’s chateau (photo P. Hunt 2010)
As I regularly do in wineries and for vintners in California wine country, I presented a history of ancient wine lecture to the Napa Valley Vintners Association a few years ago at Meadowood, St. Helena, and met makers of several excellent sparkling wines. More than a few of these sparkling producers are offshoots of great French houses transplanted to California. For example, Chandon’s parent is LVMH, Domaine Carneros’ parent is Taittinger and Mumm Napa is owned by the French company Pernod Ricard, which also owns G. H. Mumm & Cie and Perrier-Jouët champagne. Now given the enormous worth of the global champagne industry since Barbe Nicole Ponsardin-Clicquot (in France 322 million bottles of champagne were sold in 2008, with at least $3.5 billion or more in sales ), champagne bubbles and their non-French effervescent cousins are entirely worthy of the scientific study they can easily afford.
After initial natural fermentation when fruit sugar and yeast mix in the air, champagne requires secondary yeast and sugar in addition to what nature puts in, producing carbon dioxide pressure from the CO2 gas trapped in the liquid. The volume of trapped carbon dioxide begins its release when the wide-based cork is popped from its high-pressure wired tight contact with the champagne bottle’s enlarged rim.
Flutes produce a better aroma of bursting bubbles than wider rim glasses partly because they both increase the distance bubbles rise, also increasing the kinetic energy of the bubbles, and concentrating the surface area; indeed the whole liquid surface of a concentrated champagne flute participates in the bubble-bursting at a greater rate, which enhances the champagne aroma, especially of a great champagne.
(photo P. Hunt 2011)
As Liger-Belair informs, people often assume the higher quality of a champagne based on a smaller size of individual bubbles. The old adage “the smaller the bubbles, the better the wine” is partly true aesthetically as well as physically. Smaller bubbles “rise more leisurely…and consequently create the wine’s characteristically lingering sort of effervescence and delicate inner glow.” But better, vintage champagne is also usually older, meaning that it has lost some carbon dioxide and presents a lower bubble rate. 
The bubbles in champagne and sparkling wine may start out at around 20 micrometers in size from nucleation sites on the glass but can grow to 1 millimeter just before reaching the surface. The bubbles increase in size mostly because of the decrease in surrounding liquid pressure as they approach the surface.
Growing Champagne bubbles (photo courtesy of Gite-Chamery, Champagne, France)
The velocity of migration of champagne bubbles upward in a column is such that only the top of a bubble rises above the surface. Then the liquid around the bubble crown drains downward in a time span of between 10 to 100 milliseconds and the bubble crown is reduced to a thickness of 100 nanometers, too thin to sustain itself and it ruptures. The collapsing liquid rushes inward, collecting itself in such a way as to send a tiny jet upward that breaks into droplets. These droplets traveling several meters per second can also reach a height above the liquid of a few centimeters, which can be felt on the face if the champagne flute is full.
According to Philip Ball from the research of Vandevall et al., the popping sounds of champagne bubbles are in fact like avalanches where each bursting bubble seems to affect the others. There is a mathematical relationship – described as a power law – not only where the duration of a bubble’s “life” is unpredictable but so is the time gap between bubbles bursting. As champagne bubbles burst, they unpredictably compel other bubbles to change shape and possibly pop as well, but it is at a so-far unknowable rate. If you bend down and listen to the champagne fizz or feel it on your face, someone will probably jump to the conclusion you’ve reached your limit unless you can convince people you’re a scientist like Liger-Belair. Such is the nature of the "fizzics" of champagne.
Some say there are up to 50-100 million mesmerizing bubbles in a bottle of champagne,  but if you try counting more than a few, you’re probably beyond the state of Russia’s Peter the Great (à la Kladstrup) who nightly took - along with other more warm curves - four bottles of champagne to bed. Perhaps those are the kinds of parabolas Archimedes could have only dreamed to measure in Elysium.
Philip Ball. “The Fizz-ics of Champagne.” Nature Science Update (2001).
Gérard Liger-Belair. “The Science of Bubbly”. Scientific American (December, 2002)
___________________. Uncorked: The Science of Champagne. Princeton University Press, 2004, 3, 8, 59 & ff.
___________________. “The Physics and Chemistry behind the Bubbling Properties of Champagne and Sparkling Wines: A State-of-the-Art Review”. Journal of Agricultural and Food Chemistry 53.8 (2005) 2788-2802.
Don and Petie Kladstrup. Champagne: How the World's Most Glamorous Wine Triumphed Over War and Hard Times. Harper, 2006.
Tilar Mazzeo. The Widow Clicquot: The Story of a Champagne Empire and the Woman Who Ruled It. Harper, 2008.
Guillaume Polidori, Philippe Jeandet and Gérard Liger-Belair. “Bubbles and Flow Patterns in Champagne: Random Effervescence.” American Scientist 97.4 (July-August 2009) 294.
Jancis Robinson, ed. The Oxford Companion to Wine. Oxford University Press, 1994.
N. Vandevalle, J. F. Lentz, S. Dorbolo and F. Brisboi. “Avalanches of Popping Bubbles in Collapsing Films.” Physical Review Letters 86 (2001) 179-182.
 Jancis Robinson, ed. The Oxford Companion to Wine, Oxford University Press, 1994, 210.
 spumatio –onis, fem.: a “foaming”; spumo, spumare, “to foam” in C. T. Lewis and C. Short. A New Latin Dictionary, 1907, 1747.
 Robinson, 912.
 The Roman or Gallo-Roman chalk crayères can also be accessed by Veuve Clicquot, Heidsieck, Taittinger and Ruinart champagne maisons.
 Report of the Comité Interprofessionnel des Vins de Champagne (CIVC), 2009; Liger-Belair reports 262 million bottles at $3 billion in 2001.
 Liger-Belair, 2004, 8 & ff.
 others are far less conservative, with fivefold higher estimates of up to 250 million bubbles in a single bottle.
Copyright © 2011
Dr. Patrick Hunt