8 ms·
Mindblowing Experiment demonstrating Laminar Flow
- dhughes 15y agoUnblending, pretty amazing.
- kenjackson 15y agoCould you do that with a spoon in a large bowl? Or does the unmixing need to be extremely precise?
- wiredfool 15y agoThe 'mixing' needs to be as pure laminar flow as possible, and that's generally between two cylinders that are rotating at different speeds. The speed of the fluid across the space should be a linear function of the relative distance from each wall. Any variation of that is going to reduce the reversability. So what they're doing is very carefully not mixing, but shearing. The fluid here is behaving like a very soft chunk of rubber, not like any fluid that you're used to dealing with. If you've got a spoon, there's going to be some turbulence as the flow goes around the edges and the flow detaches from the surface. Turbulence absolutely destroys the reversibility.
- kenjackson 15y agoThanks. You just saved me cleaning up a big mess in the kitchen.
- onedognight 15y agoYou can use a spoon, but yes you have to extremely precise. What matters is that you exactly reverse your forward motion. It's an entirely geometric effect though, so it doesn't matter how fast you go forward and backwards as long as you stay slow enough to be in the Stokes regime.
- malvosenior 15y agoGet a damn clamp.
- timdorr 15y agoSo, it's a sort of fluid-based, reversible encryption?
- onedognight 15y agoActually, yes. The path you take to stir the fluid would be your key which would be verified by getting back to the initial dye state. The key size would be ideally infinite dimensional (the dimension of the path space), but practically bandwidth limited by your ability resolve the dye pattern.
- ahi 15y agoVery cool, but it seems they had some trouble counting to 5.
- chopsueyar 15y agoAwesome. If you like laminar flow stuff, check out these DIY laminar fountain videos: http://www.youtube.com/watch?v=SEqrRV0jMw8 http://www.youtube.com/watch?v=SEqrRV0jMw8 http://www.youtube.com/watch?v=7sDs_r91uJE http://www.youtube.com/watch?v=7sDs_r91uJE http://www.youtube.com/watch?v=Ijn98G0I99E http://www.youtube.com/watch?v=Ijn98G0I99E (very ad-laden, beware) If anybody has plans or instructions on how to make a laminar flow sheet of air (air curtain), please reply.
- espeed 15y agoIs this analogous to the quantum mechanics theory that information cannot be lost or destroyed and everything is therefore reversible?
- abecedarius 15y agoIt's an instance of it, though classical physics has the same property. Feynman introduces this stuff in http://www.youtube.com/watch?v=_Kab9dkDZJY http://www.youtube.com/watch?v=_Kab9dkDZJY
- dzuc 15y agoBohm uses this as an example of implicate order: http://en.wikipedia.org/wiki/Implicate_and_explicate_order_according_to_David_Bohm#Quantum_entanglement http://en.wikipedia.org/wiki/Implicate_and_explicate_order_a...
- Xk 15y agoIf you were like me and wondered why they had to go back six after going forward five, it's because they counted wrong. They go forward six and a half turns, and go back six and three quarters.
- erydo 15y agoI noticed it when they miscounted, and it was kind of interesting how it happened. The professor talked through a revolution, and then resumed counting from his previous number. The student who was counting in the background just sort of reset to the professor's count instead of correcting him, and it seemed entirely subconscious. Not mindblowing, but I found that little moment more intriguing than the laminar flow.
- eli_s 15y agowow this is what reversing entropy would be like if it were possible - I'd love to have a rl undo button :)