BAN #208: Zombie fic, Sand dune movement video

[Spiral Galaxy M81 image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona]

Microfic

A short short story

Once upon a time there was a website called Ficly. It still exists, but it’s been frozen; no longer updated. I heard about it through Wil Wheaton: Once you signed up you were presented with a text field that would only allow a maximum of 1024 characters, including space breaks. Your task was to write a story within that limitation.

I love exercises like this. A very rigid framework means you have to be clever, you have to really think about what you’re doing. I had a couple of ideas so I tackled them there, and found it to be invigorating. If you ran out of chars, you had to do something, like use a shorter synonym for a word. Can’t fit unmoving? How about static then? Sometimes the switch wasn’t great, and you had to sacrifice. But even that is a good lesson for a writer.

What follows is not exactly what’s on Ficly; I decided that for the newsletter here it did need a few more words. Not many, though. You do the math.

Random Walk                 

Hey, look, I know a mathematician’s an unlikely survivor. But it’s not like there’s a list of axioms to follow here.

They’re not fast but they’re ubiquitous. By the time I realized I was in trouble, options were limited. A house loomed ahead, the door slightly ajar. I ran in, and there was only one way to go: up. I locked the door, quickly made sure the place was unoccupied and the windows  secure, and ran up to the second floor.

My timing was good. I went from room to room to look out the windows; I could see them slowly converging on me radially in a rough, asymmetric circle. No discontinuities, no way to get past them. After a minute or two the rotting, writhing mass was right below me. I should’ve predicted this, I guess, but in my defense I was in a hurry and I didn’t know all the initial conditions.

I didn’t see how the pile got started. Extrapolating backwards, I can guess it was one of them in advanced decay. It bumped into the house and fell apart. There must’ve been dozens before it that stayed intact and scattered away in a different direction, but statistics won’t be denied. Have a big enough sample, and unlikely events become inevitable.

Once seeded, the pile grew. Another fell, and another. They don’t climb, really, but they can walk uphill. One on the pile, then another. Thrashing feebly but staying down. I had plenty of time to do the math. Given their speed, average size, direction, I calculated how long before they’ll reach this window in front of me: 6 to 8 days. Plus or minus.

I checked. Even rationing, I have 7 days of food here. I suspect in week or so, I’ll have one last equation to solve.

Astro Tidbit

A brief synopsis of some interesting astronomy/science news that may be too short for the blog, too long for Twitter, but just right (and cool enough to talk about) for here.

The website FYFD is a pretty cool place that explains various phenomena due to fluid dynamics, doing so in a way that an interested science enthusiast can follow. It’s always interesting, but one article posted recently was really cool.

Sand dunes migrate as wind blows over them, moving sand from the back side to the toward the leading edge. Only some sand grains move at any one time, but the overall effect over time is that the entire dune moves downwind. It’s also been known for a long time that sand dunes of different sizes move at different speeds even in the same wind. If that’s the case, how come faster dunes upwind don’t catch up with slower ones downwind?

[Sand dunes on Mars. Credit: NASA/JPL-Caltech/Univ. of Arizona]

The article at FYFD explains it (with some cool animated GIFs). As wind flows over the upstream dune it creates turbulence, which then sweeps over the downstream dune. This moves the grains faster, equalizing the speeds of the dunes, effectively keeping them separated. The article goes into more detail.

I love stuff like this. It’s a seemingly simple question based on simple observations, and a cool experiment can show what’s happening. Mind you, this has cosmic ramifications: We see turbulence in gaseous nebulae as well as inside stars, profoundly affecting how these objects behave. Huge focused beams erupt from black holes and supernovae and very young stars, with matter screaming away at high speeds. Sometimes we see faster blobs inside these beams catch up with slower material farther out, creating shock waves and heating them up, as well as generating turbulence. I’m not saying this dune experiment directly applies to these situations necessarily, but turbulence is fiercely complex mathematically, so the more we understand it in different situations the better overall we can model it.

The thing about science is that it’s a way of understanding the Universe, and reveals a set of rules that governs the way the Universe behaves. If a rule applies in one place in a certain way, it should apply (perhaps with some modifications) elsewhere under slightly different circumstances. If it doesn’t, then likely we have something wrong. The whole thing has to work. That’s why I liken science to a tapestry; if one thread is out of weave it impacts the entire pattern.

From sand dunes on Earth to black holes at the edge of the observable Universe, it all hangs together.

Et alia

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