Mindblowing Experiment demonstrating Laminar Flow

I 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.

The '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.

You 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.

Actually, 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.

It's an instance of it, though classical physics has the same property. Feynman introduces this stuff in http://www.youtube.com/watch?v=_Kab9dkDZJY

Bohm uses this as an example of implicate order: http://en.wikipedia.org/wiki/Implicate_and_explicate_order_a...