## Archive for June, 2014

### It's not New, so it's not Really News

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.

### Golly Gee Willikers — Science!

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…

### What it Means to Get Wet

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

### Oh, You've Met?

It can be pretty awesome when these two get together.

Art Meets Mathematics: Dizzying Geometric GIFs by David Whyte

### It’s Not All Black and White

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.

I’ve been a little under the weather this week, so apologies for ignoring the blog. Catching up with my internet scouring. Here’s some Music + many illusions from OK Go

### This Goes Way Past 11

10 Scientific Ideas That Scientists Wish You Would Stop Misusing

From a purely physics perspective I’d include quantum on its own, because of the way it is misused: it does not mean big, it means discrete. A quantum leap can be the smallest possible leap you could make.

### Isn't it Time?

“Our words can have a huge impact. Isn’t it time we told her she’s pretty brilliant, too? Encourage her love of science and technology and inspire her to change the world.
–Reshma Saujani, founder of Girls Who Code”

### Professor Plum in the Wine Cellar with a Sharp Instrument

How Atomic Particles Helped Solve A Wine Fraud Mystery

I’ve mentioned wine fraud sleuthing before, and this is another telling of one of those stories. If interested, it’s probably worth reading Jennifer Ouellette’s post and her included link to the New Yorker article, for full coverage of the details.