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APPLIED FIZZICS · Field Notes · Edition No. 8
A whimsical look at the universe through a glass of Champagne...or your favorite cocktail.
August 18, 2026 · Seattle, Washington
Dear Reader,
Last week we dispelled the urban legend that tapping on a shaken beer can does any good in tamping down the explosive foaming. Then we answered the question of why shaking the can causes it to spew in the first place.
Then we asked this question:
Last Week's Quiz
Question: You pour a flat beer into a pressure bottle, put on a pressure cap with attached gauge, and pressurize the bottle with CO₂ to about 40 psi.
What will happen to the pressure gauge when you shake the beer?
- A. The pressure gauge will go up.
- B. The pressure gauge will go down.
- C. The pressure gauge will stay essentially the same.
The correct answer is B—the pressure gauge will go down.
The beer in the bottle is flat. So before we pressurize the bottle, it is in equilibrium with the tiny amount of CO₂ in the atmosphere, whose partial pressure is only about 0.006 psi (about 0.04% of the atmosphere).
Once we pressurize the bottle, there is far more CO₂ in the headspace than would be in equilibrium with the beer at atmospheric pressure. CO₂ therefore begins moving from the headspace into solution, lowering the headspace pressure.
Shaking greatly speeds this process by dramatically increasing the area of contact between the beer and the high-pressure CO₂, while constantly renewing that interface. What might otherwise take hours can happen in seconds with agitation.
This is the essence of forced carbonation.
Over the past few weeks, we've spent a lot of time talking about how CO₂ gets out of a beverage. We talked about nucleation sites, agitation, increases in temperature.
This week, let's look at how CO₂ gets into solution.
One way is to simply force it in.
And let's see if we can actually weigh it.
Weighing the Invisible
Carbon dioxide is invisible, of course. But it isn't weightless.
So I wondered: Could we actually put a bottle of water on a scale, force CO₂ into it, and watch the bottle get heavier?
There's only one way to find out.
The experiment is almost embarrassingly simple. We put a bottle of water on a scale and tare the scale to zero. Then we add CO₂.
The bottle gets heavier.
We shake the bottle, forcing some of that CO₂ from the headspace into solution.
But the weight doesn't change after shaking.
That last observation is obvious once you think about it. Shaking hasn't added anything to the bottle or taken anything away. It has simply moved CO₂ from one place to another—from the gas above the water into the water itself.
But now there's room in the headspace for more CO₂.
So we pressurize the bottle again.
And the weight goes up again.
Pressurize. Shake. Pressurize. Shake.
After a few cycles, the scale stopped climbing. We reached equilibrium, with about 11 grams of CO₂ added to the bottle.
And those 11 grams weren't water. They weren't bottle. They weren't cap. They weren't anything we could see.
That 11 grams was carbon dioxide.
Then we removed the cap and let the pressurized gas in the headspace escape. The scale dropped from 11 grams to about 7.
So where did those 11 grams reside?
Roughly 4 grams escaped when we opened the headspace. About 7 grams remained behind, mostly dissolved in the water.
That's an interesting result in its own right. The CO₂ in a carbonated beverage isn't all dissolved in the liquid. A substantial amount is sitting in the apparently empty space above it.
In our little experiment, the split was roughly 40% released on opening and 60% remaining.
And that brings us back to something we've encountered before: the headspace matters. A lot.
Physics Corner
Why 60/40?
Why did roughly 60% of the CO₂ remain in the liquid while about 40% escaped from the headspace?
That ratio turns out to have an interesting explanation involving Henry's Law, temperature, pressure, and the relative volumes of liquid and headspace.
But for now, let's just point out one thing: CO₂ has more ways to exist in solution than in the headspace. In the headspace, CO₂ is just individual CO₂ molecules bouncing around. But in solution, CO₂ can swim around as individual aqueous molecules, and react with the water to produce carbonic acid, H2CO3.
So is that the reason more CO₂ resides in the liquid than in the headspace?
It's an appealing explanation. But is it actually true?
We take a closer look at that question—and the roughly 60/40 split—in Applied Fizzics Research Note #2.
But where does all that CO₂ come from in the first place? What puts the fizz in fizzy?
The answer depends on the beverage. Soft drinks are generally force-carbonated. But beer and Champagne can make their own CO₂ through fermentation.
Next week, we're going to look at how that happens in Champagne.
The process is simple in principle: The winemaker puts a little extra sugar in a bottle of still wine, and caps it. Yeast metabolizes the sugar and produces CO₂ and a little extra ethanol as waste products.
Until the next edition, based on what you learned in this edition, let's see if you can reason through the following question:
This Week's Quiz
Question: A winemaker puts the same amount of wine, sugar, and yeast into two identical bottles. Bottle A is tightly capped. Bottle B has a balloon sealed over its mouth to capture any CO₂ that escapes from the bottle.
- A. Bottle A
- B. Bottle B
-
C. They will weigh the same.
We're going to try to make sparkling wine by fermentation next week. Stay tuned.
Reveal the Answer
The correct answer is C, they will weigh the same.
Both systems are closed. Fermentation rearranges atoms into new molecules—including CO₂ and ethanol—but no matter enters or leaves either system. In Bottle A, the CO₂ remains in the bottle; in Bottle B, some moves into the balloon. The location of the CO₂ changes, but the total mass does not.
Until then, stay curious.
Any questions? Class dismissed.
Cheers,
Evan Wallace
President, Applied Fizzics Inc.
Makers of The Perlage System®
Want more Champagne science, carbonation experiments, and behind-the-scenes product stories? Visit the Applied Fizzics Field Notes archive .
