This may be one of the visually least impressive videos that gathered over 7 million views on Youtube. But even more than three years after the video was posted there are still fresh comments under it expressing diverse opinions.
Here’s the story: While staying at the underwater Aquarius Reef Base near Florida Keys, Astronaut Chris Hadfield decided to give us a little science lesson. He took a can of coke, shook it vigorously, opened it, and … nothing. No explosion, no foam, no sticky stains all over the table.
How is that possible?
Some answers are in the video. Hadfield explains this happens when you live in an environment pressurized to 2.5 of normal atmospheric pressure. The pressure inside the base is intentionally kept at 2.5 atmosphere—about the equivalent of diving 50 feet under water. It’s very practical, because the base is 66 feet under water, so there’s not much pressure difference between the inside and the outside. Still, 2.5 atmosphere is not that hard to get used to for people.
Now however, the explanation gets more tricky and over the years many commenters offered different ones.
“Look at that” he says, “That’s physics in motion right there, Archimedes’ principle, or…Boyle’s law, or something like that.” The cameraman throws in Ohm’s law for good measure.
Although we can assume both men were just joking around, it seems their comments confused a number of viewers.
The Ohm’s law is an obvious joke, as it has to do with electricity and the relationship of current, voltage, and resistance.
Archimedes’ principle may theoretically fool somebody, as it conjures up an image of water. But it has nothing to do with fizz in a coke. It deals with buoyant force exerted on objects immersed in fluids.
Boyle’s law however may seem like a plausible explanation. The law states that as you increase pressure on gas, it’s volume will proportionately decrease. If you increase pressure on gas, you can stuff more of it in the same space.
The problem is, CO2 gas that makes for the soda’s fizz is immune to the increased pressure inside the underwater base—because it’s dissolved in the drink.
The real explanation, as far as we were able to find out, is the Henry’s law that describes how much gas you can dissolve in liquid. It states that the higher is the pressure of the gas above the surface of the liquid, the more of the gas is forced to dissolve in the liquid.
And so, when Hadfield opened the can, the increased pressure in the base prevented the CO2 from escaping the coke too quickly.
Still, for people who didn’t come ready for a science lesson, the video may have been quite disappointing.
“Sooo did anyone else think this video would be a guy in a scuba suit opening a can underwater and something incredible would happen?” commented Youtube user James Sweetman 5 days ago.