These are just regular Rayleigh-Taylor instabilities, not spherical. The spherical case requires a gravitational field that varies radially, which is why Mark Stock simulates the physics numerically - no experimental version is possible.

I've witnessed this same thing! When I was in 6th grade and was just learning how to play the trombone, I was practicing in my grandmother's yard one evening. As I recall, I was playing "Twinkle, Twinkle, Little Star". Down at the barn, it was feeding time and my uncles couldn't figure out where all the cows were.…

Oo, it's always exciting to see FYFD make it onto io9. And thank you for even mentioning me by name! I'm Sharp with no e, though, like the pointy end.

They are barchan dunes. I believe the comparison to birds arises from the V-like formations of multiple dunes, not the shape of an individual one.

I feel your pain. My dissertation is due to the committee in 16 days.

Any updates on that women in STEM blog? I was reminded of our earlier exchange by a recent discussion with a friend about the need for such a site. Have you got it up and running?

I am indeed the one behind FYFD. I am a PhD student studying roughness effects on hypersonic boundary layer stability - basically something that I never talk about on FYFD...

+1 to the idea of a site dedicated to women scientists, and +10 to a fellow female fluid dynamicist!

I spent most of the movie hiding behind my parents' recliners. When Mom tucked me into my lofted bed that night, I asked whether snakes could climb up into my bed. She considered for a moment before saying, "Yes, probably." Then she shut off the lights and left me with my terror.

Is the dynamic stability of the Shenzhou capsule actually capable of correcting an end-over-end tumble toward the atmosphere? Most re-entry capsules are statically stable when their heat shields are pointed toward earth, but Mercury, Apollo, and other capsules are dynamically unstable under large oscillations. Or was…

You can't stop the signal.

Ha! It does seem like that man has written almost every textbook in the field, doesn't it?

Yes and no.

This is a nice article explaining one of my favorite fluids demos (and I don't just say that because I was quoted in it). I would sound one caution, however:

Yes, the droplet is completely separate from the pool. Because of the bouncing induced by the pool's vibration, there is always a layer of air separating the droplet from the pool. Otherwise, things would look like this:

As an aside, this is a different effect than the coalescence cascade, which is what happens when a layer of air trapped beneath the droplet prevents it from immediately coalescing into the pool.

Often it's not the oil itself that's fluorescent. When we use this technique in my wind tunnel, we use standard silicone oil and mix in a fluorescent powder to get the level of visibility we need. One reason to use the fluorescent mixture under a UV lamp is that it can be easier to avoid reflections off the model and…

This was from an actual test of that model. Oil-flow visualization is a standard technique in wind tunnel testing, so they wouldn't be doing it just to test the technique. Also, making a model like that is quite expensive. If they just wanted to see how the oil looked slathered on something, they'd have used a flat…

All bike helmets (in the U.S. at least) have to pass the same safety standards, but those standards themselves are considered, by those who research head injuries, to be in great need of updating. If you're interested in details, there was recently an excellent article on the subject in Bicycling magazine. Beyond…

Thanks for the shout-out and the compliment!