13 April 2011

Clouds in my Coffee: Carly Simon wins Nobel Prize for Physics

Pour a cup of hot black instant coffee. Let it sit for a while, and
carefully observe the surface. After a short while you will see a thin
film of mist form; you can move this around the surface by blowing
lightly. If you watch it for a while, you will see little local
collapses, cracks and ruptures form and propagate through the mist,
often making interesting patterns as they do so. There is some
interesting physics going on here. What seems to happen is that there
is a vapour layer at the interface of the hot liquid and the
relatively cooler air above that creates a semi-stable (and very thin)
zone. If a particle of dust (or maybe a particle from a radioactive
decay process? Need to do some testing of this!) interacts with the
layer, it seems to cause a local collapse of the condensate zone that
propagates through the rest of the zone like a crack appearing in a
sheet of ice. So what is going on? It sure looks like an interesting
phenomenon, so I have tweeted everyone's favourite physicists
@ProfBrianCox and @JimAlKhalili to see if they know, or if there is
any literature on the topic. If not, I will make a pitch for the
IgNobels, as I think coffee is too important to be ignored.

[Works with black tea too]

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