When you pour a cup of hot coffee, there’s a surprising amount of chemistry and physics brewing in your mug.
That rich coffee aroma rises from the steam because roasting coffee beans converts bitter chlorogenic acid into a diverse set of compounds. Some smells you’d expect-fruity, spicy, earthy, vanilla-but there are a few surprises (cabbage??). And adding a splash of milk or sprinkle of sugar sets off a chain of physical reactions. Convection makes the cold milk sink while the interactions between milk and coffee molecules create the milky swirls. Brownian motion also will spontaneously mix the coffee over time, no need for a stirrer.
Watch Reaction’s newest video below to learn more about what happens inside your morning pick-me-up, and how it relates to the chaos of the universe.
The views expressed are those of the author(s) and are not necessarily those of Scientific American.
Lydia Chain is a freelance science journalist, podcaster, and videographer. She hosts Undark's podcast, and also writes about nature, the environment, and evolution, especially when it involves the intersection of humans and wild spaces or animals behaving strangely. Follow Lydia Chain on Twitter