Light pollution and Goodharts's Law
It may well be that as we’re all getting richer we use more light and therefore we can see fewer of the stars in the night sky:
It was not to be. The night sky was not so much black as dark grey with only a handful of stars glimmering against this backdrop. The Milky Way – which would once have glittered across the heavens – was absent. Summer’s advent had again revealed a curse of modern times: light pollution.
The increased use of light-emitting diodes (LED) and other forms of lighting are now brightening the night sky at a dramatic rate, scientists have found.
Perhaps expanding the area in which the drunk can look for his keys is worth not being able to see the stars. But we’d just like to point out that it’s not LEDs causing this. Quite, quite, the opposite.
The biggest change in lighting in recent decades has been the ongoing replacement of the old sodium/scandium bulbs for street lighting with LEDs. The big difference - other than the base technology - is that LEDs are directional. The older technology threw off light in any and every direction, the new one directs - almost always downwards. For any given level of lighting we therefore gain less, not more, light pollution.
As we’ve pointed out before one of the little absurdities of this life is that one of us used to run the shadowy international scandium oligopoly - to the extent of, for a couple of years at least, supplying 100% of the world’s non-China light bulb industry.
We can approach a proof here from the other end as well. Measuring GDP growth by measuring the light that can be seen from satellites was first a new idea, now it’s become standard to the point that the World Bank uses it. At first it was a useful idea too. But then comes Goodhart’s Law.
Goodhart’s being the point that once we start to use a measure as a target is ceases to be a good measure. A strict application of that here would imply those who would fool us about economic growth shining searchlights at satellites. No, we do not suggest that is happening.
But we have had this technological change. From omnidirectional to unidirectional street lighting. Which disrupts the relationship between observed public lighting and economic growth. There is even a way to correct for this (we’ve suggested it to at least one researcher, look for the specific spectral markers Sc produces and alter for that, we don’t know whether it has been adopted) but it is true that the link between light and growth is changing. Some are taking this to be growth which is, perhaps, being lied about more. We would insist that at least some of it is because lighting technology has changed.
Unless we’re going to call into evidence some extreme version of Jevon’s Paradox here LEDs are part of the solution to this problem, not the cause of it.
BTW, the LEDs don’t use scandium, it was this exact technological change that broke the oligopoly part of that shadowy international scandium conspiracy. As all monopolies and oilgopolies always do get broken, eventually, by technological change.