There's something I've been meaning to rant about for quite some time. Sadly, I'm at an age now where, when this certain something occurs, I instinctively say to myself, "I'm going to rant about this!" but then forget about it completely once it passes. Well, for some strange reason, I was reminded of this certain something today while not experiencing it and while in the vicinity of my laptop.
A couple years ago, the city I live in joined a growing movement to reduce "light pollution". As such, the majority of all street lights have now been changed to cast only a small amount of light directly downward, instead of spilling it frivolously in large pools. The effect is such that we no longer have to worry about about our sidewalks, pathways, and roads being safely illuminated. Instead, we can rest assured that the deep, penetrating darkness of night is only marred by near-illumination every hundred feet or so. The "light pollution" that so threatened us in the past is, well... a thing of the past.
Or is it?
Another trend of late is the ever-increasing brightness of car headlights. It would seem that automobile manufacturers have determined that safety is best provided by bathing an area 50 feet wide and 100 feet deep in front of the vehicle with a blue-white light of an intensity normally reserved for police helicopter spotlights. Headlights operating in the normal mode are now brighter than "hi-beams" used on highways and rural roads as recently as 15 years ago, allowing drivers to make out every crack in the asphalt, every blade of grass alongside the road, and every pore on the face of the oncoming driver.
Perhaps this shift is in response to the change in the street lights. Possibly, auto manufacturers are simply helping to compensate for the reduced lighting. Regardless, it is having another, far more negative, effect.
You see, the human eye is a marvel of evolution with its ability to adjust to different light levels by widening or constricting the opening of the pupil. In darkness, it dilates to allow more light to pass through to the retina. In bright situations it contracts, restricting the amount of light and preventing our optic nerve from being "over-loaded". Yet, as amazing as this organ is, it still has its limitations.
One of these limitations is never more obvious than when I am driving at night.
Our less-than-adequately-lit streets cause my pupils to dilate enough to allow me to see where I am driving. No problem so far. Let's add an oncoming Porsche SUV with high-intensity, broad-angle, halogen headlights and see what happens, though. Instantly my pupils contract and all I can see are the headlights. The rest of my world is a blackened void, into which I am driving at 50 km/hr, hoping the clear stretch of road I remember seeing before being blinded remains that way long enough for the SUV to pass and my sight to be restored.
Heaven help the black-clad jaywalking jogger that gets in my way.
In a by-gone era where the amount of light provided by street lights and headlights was not so vastly different, my eyes would never have had to make such radical adjustments and neither the safety of myself nor that of the fashion-conscious jogger would have been jeopardized. In that same by-gone era, however, we wouldn't have traded safely-lit streets for less "light pollution" (for which I will continue to use quotes until I'm convinced it's a real thing) and we wouldn't have believed that a car driving 50km/hr in the city requires headlights strong enough for one doing 110km/hr on a pitch-black highway.
But what did we know?