At a recent South Bend Science Cafe that addressed the spectra of lights, I was bound to the main rule for presenters--you can show no slides. So what's an alternative way to present technical content to an intelligent audience? Balloons, of course! The Branch kindly sponsored Twist and Smile artist Gill Knip to bring colors to life, and likely to make the talk more memorable for its props than its content.
The First Midnight star chart, painted on the crosswalk just up the street from the hosting Chicory Cafe, features the bright star Eltanin in Draco the Dragon. Eltanin is approximately 150 light years away, so the light that left the star when South Bend was founded is just now reaching our eyes, after traveling 150 years at 186,000 miles per second. Of course, we used a string of balloons to depict the constellation with South Bend's birthday star Eltanin. Shown is Phil Schreiber, right, of Chicory Cafe holding Draco with me. (Image: Bruce Miller)
On January 19 we launch SB150 Young Astronomers, an initiative to teach astronomy and telescope use to middle- and high-school students in the community. They then get access to a global network of research-grade telescopes to capture their own images of deep space wonders. A balloon telescope on a tripod, below, reinforced the description.
Two local projects that may impact the night sky in 2015--River Lights and Light Up South Bend--segued into the bigger topic of the night--namely, the promise and the peril of LED lights. This dovetailed with the 2015 International Year of Light (& Light-Based Technologies), for which we displayed a giant balloon decoration of the 2015 IYL logo.
Seven volunteers held 14 colored balloons to show a spectrum of colors. I pre-labeled each balloon with four different heights to simulate four separate light features. For example, our photopic sensitivity peaks around 550 nm, around the green, so the seated volunteers held their balloons to make a nice bell curve that peaked around green.
Then I introduced the eye's photosensitive ganglion cells in the front of the retina that send a signal to the suprachiasmatic nucleus (SCN). The SCN is the conductor of time-sensitive body functions, such as alertness, body temperature, sleep, and the production of melatonin. Each day your body resets its clock by what had been the evolutionary certainty of day and night. This circadian system gets its cue from daylight, and the circadian sensitivity peaks around 450 nm, or in the blue light. The volunteers then lifted their respective colors to show a curve dominated by blue balloons.
Again, your body evolved over millions of years to sense what Louis Armstrong called "bright blessed day, dark sacred night." Thank you, audience, for joining me in song.
Nowadays, however, the distinction is muddied, as we rarely attain full darkness of a Genesis night. While our bodies produce melatonin in the absence of light, we don't always give it the darkness it needs. One impact has been the increase of breast cancer in shift workers like nurses, who work through the night with no daily respite from intense lights, to the point that the World Health Organization has declared shift work a probable carcinogen.
Back to LEDs. The Nobel Prize in Physics 2014 went to three persons who developed blue-rich LED lights. The balloon curve for blue-rich LED light peaked in the blues exactly where the circadian system is most sensitive.
The take-home message was to turn down the blues when your body should be experiencing darkness. Practical tips include avoid blue-intensive lights at night; turn off computers, tablets and cell phones in the late evening, or at least use an app like f.luxthat automatically lessens the blue output from monitors and screens (yet can be over-ridden if necessary); and buy LEDs under 3000K. LED lights have great upsides, so install and use them wisely.
The year 2015 holds much promise for South Bend in the realm of astronomy. Together, let's value and respect a dark sacred night. Act as if our well-being depends on that evolutionary certainty, because it does.
The ensuing Q&A yielded further dialogue that I may add to this page at a later date.
I thank the audience for its participation; Jessica Baron and the John J. Reilly Center for its Science Cafe support; The Branch for sponsoring the balloon attraction; Gill Knip for her balloon handiwork; and Chicory Cafe and its staff.
Each balloon was marked with the four respective y-axis heights, such as the green simulation below. The volunteers would hold the balloon at the proper heights, with their fists on the respective mark and their fists aligned horizontally to be the x-axis. I had planned on using a sheet to hide the bottom portion of the balloons and to give the x-axis more definition, but hey, it's Science Cafe and that would have been too formal and too much effort, especially since we had 14 balloons and 7 volunteers.
The resulting graph for, say, the blue-rich LED light, would in theory look like the simulation below.