I wrote about the dynamics of colliding sand dunes this week; Brian Romans of Clastic Detritus and Jennifer Ouellette of Cocktail Party Physics also blogged sand dunes without any collusion between us (much less collision). Brian retroactively declared this week Dune Week as a result, and I heartily agree.

• Sand dunes on Mars, from Brian Romans: Grain Flow on a Martian Dune.
• Of Granular Material and Singing Sands by Jennifer Ouellette: some of the intriguing behavior arising from sand, which acts as a fluid but can support weight like a boss solid. Bonus: why Brazil nuts rise to the top of a container of mixed nuts!
• Update: Matt Hall added his contribution in the comments below: “Wave-Particle Duality”, about transitional behavior between barchan dunes and parabolic dunes.
• My own Dune Week post: Tsunamis of Sand in the Sahara.

Other non-dune links of excellence:

• My NASA tweetup colleagues PJ Sykes and Catherine Leth posted their own impressions of NASA Langley. Catherine’s photos are particularly wonderful (and I’m not just saying that because she let me steal two AA batteries from her).
• Work is underway to redefine the international standard of units of measurement (Système International or SI), known commonly as “metric”. As you can imagine, this is a major undertaking; though it won’t affect most of us directly (since any alterations are deep in the decimal places), it’s the way scientists and engineers ensure precision. Here’s what the National Institute of Standards and Technology has to say about it; the biggest change is to the definition of the kilogram in terms of fundamental constants of physics, to avoid the problem of mass-loss in the current kilogram prototype.
• The next round of OPERA results confirm that neutrinos still appear to be traveling faster than light, though the effect is smaller than in their earlier results. I beg of you all, please don’t buy into the “Einstein was wrong” hype. In fact, what I wrote previously still stands (though I may yet be incited to write again about neutrinos).
• A new theorem in claims to show the physical reality of the quantum wave function, which is usually regarded as probabilistic in character. I am really hesitant to pass judgment on the story yet, because I haven’t read the original papers. If this result holds up, it would have profound implications for how we understand and teach quantum mechanics. Trust me, I will return to this topic soon!