Linenger's Letters to his Son

February 4, 1997
"
Physicists love this stuff"

Dear John:

I bet your're glad to get back into your own crib, play with your toys, and see all your Russian friends again. And they will be overjoyed to see you again.

They'll see how you've grown, what new tricks you've learned, and how much smarter you've become. Have fun impressing them, John. When I return, I'm sure going to have a blast enjoying your new self. There is nothing finer on planet Earth than your own son. All fathers must feel that for their sons. Daughters, same way I'd suspect. A real gift. A real joy.

An experiment surprised me today. Fluid physics stuff. Wetting. Surface tension. Reaction of fluids to wedge angles. Liquid bridges. Physicists love this stuff--they're trying to predict the reaction of fluids in space, and will study the films I made for hours. Analyzing away.

You'd like the device, John. Like a toy. You open a valve and squirt this red Kool Aid stuff into a chamber. Turn a dial to raise the level. Turn another to change the squeeze angle all the while going back and forth on the first dial in order to keep the fluid from shooting up the vessel wall. Like an Etch-A-Sketch.

The surprise was this. The scientist who designed this thing expected the fluid to fill the "floor" of the second chamber when I opened the valve. But space is different. Earthly assumptions don't hold. To the fluid, the "wall" was just as good a place to start off as the "floor"--so it started filling there. Spread up the "wall" immediately; formed a meniscus eventually, and then made its way along the "floor" and "roof" when I decreased the squeeze angle.

If I lost you, let me simplify. An empty swimming pool. Turn on the hose to fill it. It starts filling up--but not from the bottom up, but from one side across!

In my view, there could not have been a better result. Something unexpected happened. We advanced our knowledge of the fundamental behavior of fluids. And it was only possible to do this in space. The mold killed the bacteria.

Well, John, I'm really tired. Time to crawl into my sleeping bag. Pleasant dreams to you and Mommy. I love you both.

Dad.

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