Every morning it’s the same: A few drops of coffee end up on your table. And once they dry, they form ring-shaped stains. But why? This problem is related to the question how to build tomorrow’s communication systems.
Some of you might remember your grandma’s coffee pot, which had a sponge attached to the spout. This was done to avoid coffee stains. These stains – black on the outside, white on the inside and always round in shape – are also interesting for science, especially for nanotechnology.
Physicists might use the coffee stains as a model to design better communication systems in the future. This is why the question of the month reads:
“Why does coffee always form ring-shaped stains and not a chaotic splash?”
Detektor.fm asked Leonie Anna Mueck, Editor of the Journal of Unsolved Questions.
Read more about self-assembly in colloidal dispersions here: A. Marin et al. “Order-to-disorder transition in ring-shaped colloidal stains”, Phys. Rev. Lett. 107, 085502 (2011)