1950–1970 was a true golden age for American science.

By any quantitative measure you choose, the size of the scientific enterprise grew exponentially from its founding around 1700 until about 1970. Thus, the cumulative number of scientific journals grew from a few around 1700, to 10 around 1750, 100 around 1800 and so on, reaching 100,000 around 1950. Similarly the number of physics PhDs in the United States grew from the first awarded in 1870 to about 10 per year in 1900, 100 per year in 1930 and 1,000 per year around 1970; but then the growth stopped abruptly and the total has fluctuated around 1,000 per year ever since.

This sudden end of exponential expansion accounts for many of the difficulties we scientists have faced since then. The period 1950–1970 was a true golden age for American science. Young PhDs could choose among excellent jobs, and anyone with a decent scientific idea could be sure of getting funds to pursue it. The successes of science projects during the Second World War had paved the way for the federal government to assume responsibility for the support of basic research. Moreover, much of the rest of the world was still crippled by the after-effects of the war.

At the same time, the GI Bill of Rights sent a whole generation back to college, transforming the US from a nation of elite higher education to one of mass higher education. Before the war, 8% of Americans went to college, a figure comparable to that in France or the UK; now, more than half of all Americans receive some sort of post-secondary education. The expanding academic world of 1950–1970 created posts for the exploding number of new science PhDs, whose research led to the founding of journals, the acquisition of prizes and awards, and increases in every other measure of the size and quality of science.

But around 1970 there was a phase transition, all of those factors turned back on themselves. The golden era of exponential expansion had come to an end. We will all have to wrestle with the consequences of that transition for the foreseeable future.