I remember a journal club where we read a paper in which they demonstrated the inverse brazil nut effect (http://large.stanford.edu/courses/2007/ph210/spector2/). The scientists built a physical nut shaker- like, a huge tube that they bounced. that's when I realized I had picked the wrong field (theoretical biology instead of experimental physics).

Farmers know the rocks come to the suface over the winter.

This is a recurring problem in the animal feed industry. Easiest explanation for the phenomena: the small particles fall through the gaps gaps between the large particles.

My first instinct would be that this is due to entropy rather than minimizing energy, but the article doesn't mention that hypothesis. Is it easy to rule this out?

Here I was this morning just thinking about this - weird how that happens.

My wife got this gift recently, that at first looks like a snowglobe, but actually has fine sand and seashells inside. You can kind of shake it or rotate it about, and the seashells that "rise" to the top on the sand change as you do it.

For some reason, that got me thinking about this topic. Then I see it on HN...

this also has application in mixed spice grinders. you can shake it right side up or upside down to get the desired effect