The conveniences we take for granted today usually began as niche products only a few wealthy families could afford. In time, ownership spread through the levels of income distribution as rising wages and falling prices made them affordable in the currency that matters most — the amount of time one had to put in at work to gain the necessary purchasing power. At the average wage, a VCR fell from 365 hours in 1972 to a mere two hours today. A cellphone dropped from 456 hours in 1984 to four hours. A personal computer, jazzed up with thousands of times the computing power of the 1984 I.B.M., declined from 435 hours to 25 hours.
It’s pretty obvious just looking at the chart that more recent adoption curves slope more steeply than those from longer ago. In other words, new new things are getting adopted much more quickly than older new things. It’s less obvious just from looking whether the increasing speed of adoption is itself increasing, though that may be true too.
It is also fascinating to see just how strange the unadoption of technology is. Telephones, cars, and even electricity slipped back during the US great depression – but not radios, which just kept on growing. Since World War II, growth has been all but inexorable – though a telling sign that VCR and (presumably fixed line) telephone ownership are beginning to turn down – which are the only two of the technologies which have become obsolete.
Long term planning based on assumptions about the non-diffusion of technology (not a good idea at the best of times) suddenly look even shakier.