The bubbles in Champagne are the result of a second fermentation process that happens inside the bottle. Yeast and sugar are added to the wine; as the yeast consumes the sugar, it releases carbon dioxide. Because the bottle is sealed, the gas is forced to dissolve into the liquid. A standard bottle of Champagne contains about 49 million bubbles. Interestingly, bubbles don't just appear randomly; they form at 'nucleation sites,' which are typically microscopic fibers of dust or cellulose on the glass surface. This is why some high-end glasses are laser-etched at the bottom—to create a steady stream of rising bubbles.