> Running out of steam, as in a slowdown in the growth curve on various metrics is not the same as a decline.
In the long run, it absolutely is. It's possible for any given point on the curve to have a positive first derivative and a negative second derivative, but if the second derivative stays negative, the first derivative will also ultimately turn negative.
Which also leads to questions of whether there's a long term trend at all, or if it's simply a cycle. The derivative of a sine wave is just another sine wave (technically a cosine wave but the same shape). So you don't get anywhere in The way you know you're at the peak of a sine wave is if the derivative reaches zero but you're still upwards of where you started from.teresting looking at second derivatives.
> It's simply unrealistic to expect technology and engineering to advance as fast as they did in the mid-20th Century indefinitely. We've exhausted a lot of the low hanging fruit on the science and technology trees, but there are still plenty of fruit to pick, we just need to put more work into reaching them.
Physical technology is also one of the worst indicators of civilizational decline. Completely losing technology almost never happens outside of an outright civilizational collapse--the obvious example of this being the fall of Rome and the early Middle Ages, though the notion of the "Dark Ages" is highly controversial and somewhat overstated at the very least. I'm not even sure if the Bronze Age Collapse corresponded to a decline in technology. (Though the complexity of the technology itself is also a factor--while we understand how to do it in principle, for instance, we have lost the technology to land people on the moon.)
(Social technology can be lost a lot more easily.)
Here are a handful of clearer signs of civilizational decline:
* The free-range territory of children has been declining continuously since the 20th century
* Infrastructure megaprojects. In 1886, all of the railroads in the southern United States were all converted to the standard gauge used in the North over a 36-hour period, with no expenditure of federal funds that I'm aware of. Between 1956 and 1992, the Eisenhower Interstate Highway System was constructed with a total cost, in 2021 dollars, of approximately $500 billion. The current infrastructure bill in Congress costs $3500 billion and does not, in fact, construct seven brand new interstate highway systems.
* Rising rates of obesity
* Declining levels of testosterone