There are 100 million bubbles in every bottle of Champagne.
When you pop the cork, the CO2 comes bubbling out to equalize with the surrounding air. That’s where the fizz comes from. 100 million bubbles in each bottle. That’s according to Gérard Liger-Belair, a researcher at the University of Reims Champagne-Ardenne who wrote the book (actually several) on bubbly.