Those Efficient LEDs & Light Pollution
(Originally posted June 28, 2016 on Blogger)
I came across this article on the BBC news site:
Three sad figures stand out to me in this article:
1. 83% of the world's population is affected by light pollution
2. ~14% of the world's population do not use their night-time vision
3. 1/3 of the world cannot see our own Milky Way
This got me thinking about the new LED street lights going up in major cities around the world. They are highly efficient as compared to the old standard light bulbs, and this is a good thing. Although there is that pesky Jevons Paradox.
But these efficient LEDs have a dark side (pun intended). Before I begin, a recap of the electromagnetic spectrum. We see in that part of the spectrum known as visible light... ROYGB(I)V, of which red has the longest wavelength relative to violet, which has the shortest wavelength (in visible light). Beyond red or violet, and we can no longer see the spectrum. From shortest to longest there are gamma rays, x-rays, ultra-violet, visible light, infrared, microwaves, radio-waves. Gamma to UV is ionizing radiation; short wavelengths that can damage or at least disrupt biological processes. IR is that part of the spectrum we sense as heat. Put your hand near a light bulb that's been on for more than 20 seconds and you'll feel the heat forthrightly. This is due to the standard light bulb's inefficient design. Though a light bulb gives off wavelengths in the visible light portion of the spectrum, the vast majority of its energy is output in the infrared range (heat); the part we can't see!
Put your hand near (or on) an LED light that's been on for any length of time, and you'll feel very little heat at all. This is due to its much more efficient design. The majority of its energy is output in the visible light spectrum, whereas very little is wasted in wavelengths we cannot see (ie. IR).
However, LEDs tend towards the blue-end of the visible light spectrum. These shorter wavelengths can travel much further before diffusing in the atmosphere; therefore increase light pollution.. Consider this fact alongside Jevon's Paradox, and I fear our Milky Way will fade from our view ever sooner.
In 2014, the Nobel Prize in Physics was awarded to Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura for inventing these efficient blue light-emitting diodes (LEDs). Well deserved. One can only blame human nature for Jevons Paradox, and who would have imagined blue light would become one of the worst light pollution sources on Earth? Perhaps not yet, but it's happening.
It is one thing to invent something that is relatively more efficient than its predecessor, but it is another thing entirely to educate the masses on their proper use.
The night sky was, to the ancient world, as familiar as the back of one's own hand. At worst, light pollution consisted of a few lit torches and a full moon. And on the point of torches, I invite you to watch this video by Lindybeige:
I can only imagine how spectacular and vivid the night sky appeared in ancient times. Even now I find it awe-inspiring. It's no wonder so many of the world's religions are based on the stars, how they appear, how they move... Though I'll stop short of getting into religion here, my point is simply, that the night sky is something as important to 'preserve' for future generations as nature herself.
This post isn't to suggest fixes to the problem, but to point it out... as it seems to be a negative side effect overriding the benefits of higher efficiency... I can say that perhaps less is more, and shielding street lamps and outlawing those obnoxious LED billboards is a start...