Happy aphelion to all.
For that subset of you also celebrating Independence day with fireworks (be safe): The Awesome Physics in a Simple Sparkler
(I do have a nit with this: At the end Rhett claims that a gas won’t emit blackbody radiation, but that big ol’ ball o’ gas we orbit around emits a pretty good blackbody spectrum. Get enough atoms together, and you’ll get a blackbody spectrum)
I arrived at a conclusion that I wasn’t really expecting or prepared for: Lionel Messi is impossible.
It’s not possible to shoot more efficiently from outside the penalty area than many players shoot inside it. It’s not possible to lead the world in weak-kick goals and long-range goals. It’s not possible to score on unassisted plays as well as the best players in the world score on assisted ones. It’s not possible to lead the world’s forwards both in taking on defenders and in dishing the ball to others. And it’s certainly not possible to do most of these things by insanely wide margins.
But Messi does all of this and more.
Algorithms are a fascinating use case for visualization. To visualize an algorithm, we don’t merely fit data to a chart; there is no primary dataset. Instead there are logical rules that describe behavior. This may be why algorithm visualizations are so unusual, as designers experiment with novel forms to better communicate. This is reason enough to study them.
But algorithms are also a reminder that visualization is more than a tool for finding patterns in data. Visualization leverages the human visual system to augment human intellect: we can use it to better understand these important abstract processes, and perhaps other things, too.
The transformation of a maze into a decision tree near the end is awesome.
Facebook messed with its users? I’m shocked, shocked.
Facebook tinkered with users’ feeds for a massive psychology experiment
Facebook data scientists tweaked the algorithm that determines which posts appear on users’ news feeds—specifically, researchers skewed the number of positive or negative terms seen by randomly selected users. Facebook then analyzed the future postings of those users over the course of a week to see if people responded with increased positivity or negativity of their own, thus answering the question of whether emotional states can be transmitted across a social network. Result: They can! Which is great news for Facebook data scientists hoping to prove a point about modern psychology. It’s less great for the people having their emotions secretly manipulated.
7 Public Domain Physics Comics Worth Reading
They run the gamut. Some are illuminating, funny and really helpful while others are just weird, wildly inaccurate and are terribly dated. So, my list of the top seven public domain science comics worth reading are…
The Amazing Micro-Engineered, Water-Repelling Surface That Lives Outside My Window
That’s not how water usually behaves. Water wets things. It clings to the surface and flattens out like a pancake. It doesn’t roll around like a glass bead. This leaf must have some kind of natural water-repelling surface that prevents it from getting wet.
Some slo-mo video of drops hitting a leaf at the link
It can be pretty awesome when these two get together.
Art Meets Mathematics: Dizzying Geometric GIFs by David Whyte
Incredible art piece dances with polarized light
There’s a video in the link with the art, which is a weird combination of kinetic sculpture and optical effects from polarizers. You don’t discern the actual motion of the polarizers, but you see a motional effect from the overlap. Sort of an opto-kinetic sculpture.
One thing:
Polarizers are pieces of plastic made to only allow (or disallow) the transmission of light with certain polarizations. Natural light has a mixture of all different polarizations of light, and so any one of these polarizers only filters out a portion of the light. However, if you stack two with complementary polarizations, such as one that blocks about 50% of light and another that blocks the other 50% of light, then you end up with a totally opaque whole.
To quote a phrase: that’s not how this works! That’s not how any of this works! Simple filters don’t add linearly (they multiply — two simple 50% filters would block 75% of the light), and polarizers don’t block half each. What’s actually going on is that one polarizer sets the polarization of the light (filtering the fraction that is cross-polarized), and then the second one blocks more light, both acting according to the Law of Malus
\(I=I_0 \cos^2 \theta\)
All the light is blocked for perpendicular orientations of the polarizers, and at varying levels of light at other angles. Randomly polarized light isn’t blocked by 50% — the transmitted intensity is roughly 75%. You can see single polarizers in the video, and tell they aren’t blocked by half.
The second piece is in color but only has a still shot, so I don’t know if this is color filters or polarization with birefringent materials. I’ve posted static shots of birefringent materials before, both using a static linearly polarized source (LCD); having the background and/or foreground polarization and birefringent material move might make for an interesting display.