Musings on optics, physics, astronomy, technology and life

Archive for December, 2012

Light in the season of dark

Once again I feel the need to apologize for not keeping this blog as up to date as I had intended long ago. This month began roughly, with the deaths of two friends, followed swiftly by the terrible school shooting in Newtown, Conn., which I drive by every December on the way to visit New England family and friends. We are all challenged to find the holiday spirit this year.

Our moods are not lifted by the shortness of the natural daylight in the Northern Hemisphere and the length of time we spend under our imperfect artificial lights. One recent study links our exposure to bright lights during the night hours to depression and even learning impairment. (Here’s the link to the original paper in Nature.) In other words, to lift our mood and improve our cognition, we should put down the computers and tablets after sunset and put our eyes and brains back in sync with the natural world. I’ve personally never been diagnosed with seasonal affective disorder, but I do know one thing: when I go camping during the summer, the bright sunlight all day long, coupled with the lack of artificial glow at night, makes me surprisingly ready to go to sleep early and get a full night of rest.

Whether or not you have “the blues,” check out science writer Natalie Angier’s lyrical “ode to blue” that was published in the New York Times back in October. I recall reading, in a parakeet-care booklet I had as a kid, a passing reference to the fact that a blue-chested parakeet’s feathers would not look blue if they were plucked off the bird. In recent years scientists have been paying much more attention to the structural basis of bright biological colors, including blue, as my colleague Yvonne Carts-Powell noted recently.

To change the subject … If you’re like me and most of my friends, you’ve been eagerly anticipating the release of the film The Hobbit: An Unexpected Journey. Even though the movie was quite long, I stayed through all of the closing credits so that I could catch the name of Luca Fascione, one of the software brains behind Weta Digital’s amazing visual effects. I interviewed Fascione for my January 2009 OPN article on photorealistic rendering, which explains why a deep understanding of the physics of light absorption and scattering is necessary to create computer-generated beings that look plausibly real. I’m glad the full text is available to all, because it’s a fascinating topic.

Whether you dwell in the solstice-darkened lands of the north or the summer-kissed lands of the south (like Middle-earth — New Zealand, I mean), and whatever your spiritual beliefs are, I wish you much peace in the coming year.


Oh, those Victorian photographers again…

I just stumbled upon some online galleries of 19th-century “headless” photographs, in which the human subjects seem to be decapitated.

The first link came from Twitter, and then I started clicking away until I found this and this and this. Oh, and old-time “spirit” photographs and a collection of vintage kitty cats.

Now, earlier this year I learned from Rob Gibson how the “spirit” photographs were made: Two people would pose for the first half of an exposure, and then the photographer would put the lens cap back on while one of the people moved out of the field of view. Then the photographer would make the second half of the exposure. In the resulting image, one person would look “solid” and the other “ethereal.”

Some of the “headless” photographs definitely look like paper-image cut-and-paste jobs. Others … it’s a little harder to discern. I know one commenter wrote, “Glass plates or it didn’t happen!” But paper calotypes would have been easier to cut and manipulate, don’t you think?

At any rate, these historical photographs give us some insight into what our ancestors considered humorous, believable, shocking, or just plain bizarre.