Not sure if any of you have seen them, but on our local cable channels, there is a show that comes on frequently, in which a professor teaches many interesting classes on science and technology. I've seen many good lessons and demonstrations on electro-magnetics, but I recently saw a particularly good one.

This show included excellent historical insight, as well as providing analogies with fluid mechanics, culminating in an oustanding demonstration. Personally, I've learned more in the maths and sciences due to the historical evolution of conceptual developments, then through pure derivation / experimentation. Knowing the history - the discoveries and resulting theories - which led to the existing state of knowledge, gives me a better grasp of concepts.

This episode showed the various discoveries and works of Faraday and Ampere, resulting in Maxwell's equations (which are really Heaviside's equations (Link (http://en.wikipedia.org/wiki/Heaviside)). While showing the graphs and mathematics of Heaviside's equations, they use fluid mechanics analogies, which helped most with 4 dimensional concepts like flux, as well as other aspects (pressure / potential). The highlight for me, was the discussion of "smoke rings", which are fascinating, in that they are so fragile, yet so stable, like soap bubbles. The professor created a drum (diaphram covering bucket) with a plugged hole in the bottom. He had filled the drum with a "smoke", and when he pulled the plug, he simply tapped on the diaphram and fired smoke rings that went 10+ feet to blow out candles. Think how hard it is to blow out candles on a birthday cake when you are standing right next to it, now imagine an incredibly fragile smoke ring travelling 10+ feet rather quickly, and blasting rows of candles. A flame is a very stable fluid flow structure, how can a gossamer ring travel so far and wipe it out?

It did cause me to wonder, could smoke rings burst soap bubbles? I am so tempted to build one of those drums to see.

The biggest "smoke ring" ever made is the mushroom cloud of an atomic bomb - I saw one film where it was obvious the ring was purely incandescent gases, rising straight into the sky, so many conditions exist to form and direct them. I could imagine chemical weapon "smoke ring" guns, firing puffs of nerve gas at enemies (somewhat more precise than letting the wind blow clouds of gas around).

What could such a structure tell us about designing things that need to move through fluids? Airplanes, boats, submarines, cars, etc. might one day move effortlessly through air / water due to some hidden secret of fluid dynamics that was coaxed out of smoke rings.

Anyway, I like when abstract concepts are taught using far more tangible analogies.

I remember reading an article, possibly in the magazine 'Science & Technology' about a giant smoke ring generator developed by the Allies to be used as an antiaircraft weapon. According to the article, it was a partial success.