Ah, so they're not falling through space... they are falling toward Earth as is the camera. Perhaps in a vacuum.
What I thought of immediately was the gravity of the sand particles themselves attracting each other, in the absence of any other force. Like, how planets form on a larger scale. But, nah, it looks like it's time-shifted and the attraction is happening way too fast for that.

^ It is still not fully understood why the sand behaves like this.

"...the cluster formation is driven by minute, nanoNewton cohesive forces that arise from a combination of van der Waals interactions and capillary bridges between nanometre-scale surface asperities."

Mystery solved!

>> ^HenningKO:
Ah, so they're not falling through space... they are falling toward Earth as is the camera. Perhaps in a vacuum.
What I thought of immediately was the gravity of the sand particles themselves attracting each other, in the absence of any other force. Like, how planets form on a larger scale. But, nah, it looks like it's time-shifted and the attraction is happening way too fast for that.


They are not falling in a vacuum, but I understand now that the title may appear a bit misleading. Sorry about that.

This is insanely cool. *promote.

Promoting this video back to the front page; last published Friday, July 17th, 2009 1:57pm PDT - promote requested by arvana.

Just as water is a fluid composed of water particles and air is a fluid composed of different gases and vapors, sand is a fluid composed of solid particles of matter.

^ you guys make my brain hurt.

>> ^nathanofborg:
Just as water is a fluid composed of water particles and air is a fluid composed of different gases and vapors, sand is a fluid composed of solid particles of matter.


Not exactly. The physical principles that keep for instance water clumped into droplets and the ones at work in this video are very different. But it is a well-known phenomenon in physics that radically different microscopic mechanisms often give rise to similar macroscopic phenomena. Another example is the similarity between mountain ranges and the microscopic surface of certain minerals, regarding their fractal nature.

*timeshift

Adding video to channels (Timeshift) - requested by kronosposeidon.

Gravity‽

Upvoted because I just got back from the beach and managed to get all that dang stuff out of my crack!