Curvature of the Mind

Thoughts from a Recreational Physicist

Something different about this one

Continuing on the theme of central forces. This is an initial image of the next guy I’m looking at.

This one is pretty similar to the others I’ve done except for that empty circle in the center.

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Islands of stability

This time I mapped the pendulum angle and time onto the surface of a cone to create a tunnel effect. For the parameter space I’m looking at, you can really see how the paths will converge for a while and then suddenly diverge wildly.

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Sensitive dependence on initial conditions

This next demo highlights the butterfly effect. These curves show the same pendulum as before, this version has the time axis wrapped around the center of the screen and the exponential of the angle as the radius. All the pendulums start at a very similar initial position and for some driving functions they diverge wildly and others they all stay pretty close.

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More envelopes

This time I’m not taking up all of the screen. Still working with polynomials and trigonometric functions.

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Another image

I just like this one!

 

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Rough and Random page

I’ve had this sitting on my computer for a while and thought I’d publish it rather then just leave it sitting there. This simulates a pulse of light expanding out like my compression wave examples. This time however, we are looking at a pulse of light expanding in the vicinity of a black hole. Rather than expanding out in a circular wave pulse, it wraps around the hole and circles back to the original location traveling around the hole forever.

I’m still trying to wrap my head around what this implies. Most General Relativity texts cover light cones tipping over at various distances from the black hole, and particular light paths including distances where light orbits the hole. The code is pretty rough and ugly right now, but is a fun little application of solving differential equations in javascript.

black-hole-light

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A Mandelbrot Image I’ve been working on.

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Something I’m playing around with.

This is something that I just stumbled onto while working on something else. I’ve taken a quick break from the atomic orbital viewer. I’m trying to make the IFS fractals more visually interesting. One approach is to create Mandelbrot versions of the IFS fractals which should break up the uniformity. Instead of showing one image that is an exact copy of parts of itself, each part of it would be locally similar to a different fractal. The images I’ve been creating up until this point have all been analogs of Julia sets. I’m hoping the Mandelbrot versions will turn out more interesting. It also opens up the potential of higher dimension renderings as Mandelbrot sets exist in parameter space, not the actual fractal space.

Voronoi and a trip far afield

In order to do that, I need to estimate the “basin of attraction” for each mapping in the fractal. A voronoi diagram is one way to do that. I started out just generating standard simple diagrams as a test. Sometimes images are just the best way to see what is going on. Using a very simple algorithm, I just iterated through a list of random points and colored pixels based on the closest one. That meant I kept track of the minimum distance and the matching index. Which lead to renders of that distance, followed by the sine of the distance.

Now that I’m looking at alternate renderings, I figured the easiest way to find the borders of domains was to track the second closest point as well and whenever the distances between first and second point were equal you were on a boundary. That looked ok, but lead to some artifacts.

Now that I was collecting this info, I figured I’d try to do something else with it, so I applied it to the alpha channel and switched over to the taxicab metric just for fun.

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I’m thinking about how best to handle this

I like the idea of putting demos up directly on the blog like the last one. However, they don’t show up on feed readers so you either get the text without the image and then click through. I can throw down some javascript to include a place holder link to the demo in the feed, or do excerpts, which I really don’t like, or go back to the old format of talking about something and linking to it at the end, which I don’t really like either.

Does anyone have any ideas or suggestions on how they handle this issue?

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The best surprises come from unexpected places

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This time I'm back with some more physics visualizations with a flat 2d canvas. I'm skipping over some demos of basic physics to get at some orbital mechanics animations that I found surprising. I've derived and calculated solutions for two objects gravitationally bound to each other from my freshman physics classes back in college. Then I did it again with more sophisticated mathematics, and again when I did quantum mechanics of the atom. As I think about it, I was writing BASIC programs back in high school to simulate the 3 body problem. All of those equations and simulations had some pretty severe limits. For one they only involved one or two bodies in motion. What you are looking at here are roughly 185 test particles orbiting one massive object like planets in circular orbits around the sun. While each of these test particles start close to each other, their mutual interactions are ignored. If they weren't there would be much more complicated dynamics going on. What caught me off guard was how fast the inner bodies were moving in relation to the outer planets. Whenever I had pictured the slow ponderous motion of the planets, I had pictured them moving more or less like a uniform disk. Whoa, was I wrong. The inner bodies are just whipping around at a frenetic pace, while the outer ones just plod along at a snail's pace. In fact there is a rather conspicuous divergence in the speed of motion as the distance between the particles decreases. I plan to have something more to say about that in the future. You might be wondering why I picked 185 test bodies? In this case it comes from looking at orbits in the range of 5 to 375. Which corresponds to Mercury (.4AU) to Neptune (30AU) a ratio of 1 to 75. If our solar system was build from evenly spaced bodies in circular orbits, this is what it would look like. So when I set this up, I never expected the slow graceful curve of the spiral slowly winding around the center. As I play with it, it seems so obvious, but that's why I find this stuff so fascinating. I've calculated and simulated these same orbits for well over 20 years now, and they can still surprise and awe me with just the slightest change of perspective.

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