I sit in Fluid Mechanics.

We are learning about pressure. Pressure is a strange concept. It doesn't come from any specific direction. It comes from every direction at once, even if the force only comes from one direction, like gravity pressing layers of ocean down on you. You'd think that if you swam down under the ocean you'd feel the whole weight of the ocean on your head, but instead the weight of the overlying ocean presses in from all around you, because the fluid is trying to flow outwards and it is encountering your body and more fluid, which prevents its flowing.

The lecture is moving on, but I am still a fluid element, represented as a single point with out much loss in accuracy, surrounded by the deep, blue ocean. See the little fluid element... see how it feels pressure from all sides!

And as we learn next, when you are a fluid element, and you feel equal pressure from all sides, you are a statics problem. That's easier, you know. Statics problems are easier. But not quite as interesting, useful or rewarding as dynamics problems. In order to become a dynamics problem, you must feel a little bit of asymmetric pressure. A little gust of pressure has to sweep you out of your comfortable and easily calculated static state. After that, who knows what happens to you.

I mean, we could talk about what generally happens to the fluid, where the flow lines go, how roughly defined fluid boxes seem to interact... but you would need a supercomputer running for a week to see just a femtosecond into your future as a single particle. It doesn't matter to the student of fluid mechanics what becomes of the single particle. It only matters what generally takes place as the fluid flows by. There are strict boundaries on what area of flow he cares about. Fluid elements flow in and they flow out again on the other side. For this Observer, we are born when we flow in, and when we flow out we die. Once a fluid element leaves that imaginary dotted-lined box, he thinks not on it again.

But you can bet it probably matters to the single particle. It probably cares whether it is thrown into a vortex, whether it is funneled into a long, dark tunnel, whether it adheres to the wall of the container... whether it bears a brief and terrifying foray into dynamics before settling down (perhaps too soon?) into another boring statics problem.

I know pipes and guages and conduits are out there. Waterfalls and whirlpools and breaking waves and rain. They're all out there. But for now I'm floating at medium buoyancy several meters below the surface. I can see the aquamarine rays of the sun on my sickly white skin. I feel pressure from every side.

I remain a statics problem. As such, there is nothing for me to do but drown.

I'm sorry, but as a lifeguard, I can't let you drown. I would be booked for negligence. So if you don't mind, I'm going to pull you out of the water. If you do mind, I'll just wait until you pass out, when I have automatic consent.
» Someones_Muse on 2007-09-18 02:16:51

I'm... so... confused... now. :S
» randomjunk on 2007-09-18 05:17:05

Wow... being a particle is depressing... if you're a dynamics problem... and you're going down.
» jinyu on 2007-09-18 11:09:32

That was so deep
Deep like the center of a tootsie roll pop.
» Dilated on 2007-09-19 07:14:20

Name.

URL.

[to enter your email, use "mailto:youremail@domain.com"]
Subject.

Comment.

Word verification.

Copy the first 4 characters only.

If you are a member, try logging in again or accessing this page here.