A study in Royal Society Open Science applies percolation models, used to understand volcanic gases and geological fluids, to the preparation of espresso coffee. Fabian Wadsworth, a geoscientist at Ludwig-Maximilians University, used coffee as a pedagogical tool to teach these concepts, and discovered that the same physics that explains eruptions determines optimal extraction.
Geophysical models applied to coffee ☕
Wadsworth's team analyzed the dynamics of pressurized water through ground coffee, treating the portafilter as a porous medium. By varying the grind size and compaction, they measured flow rate and resistance. The data fits percolation equations that predict the exact point where water extracts compounds without saturating the bed. This allows calculating the ideal grind for each machine and dose.
Your barista now needs a PhD 🎓
Science confirms what coffee purists already suspected: making an espresso is more complex than a volcanic eruption. But don't worry, if your coffee comes out watery, don't blame the barista; blame Darcy's law. And if you use capsules, physics can't save you from that wet cardboard taste.