A major boom in real stock prices in the US after Black Tuesday brought them halfway back to 1929 levels by 1930. This was followed by a second crash, another boom from 1932 to 1937, and a third crash. Speculative bubbles do not end like a short story, novel, or play. There is no final denouement that brings all the strands of a narrative into an impressive final conclusion. In the real world, we never know when the story is over.

The good news is that, at least in economics, I've seen movement away from its overemphasis on mathematical models of purely rational behavior to a more eclectic and commonsense approach: research that is, among other things, more respectful of insights from psychology.

News media stimulate bubbles, since stories about them boost their audience.

My clinical psychologist wife of 40 years has always had a close intellectual influence on me. When I was beginning to talk openly in the economics profession about irrationality in decision-making, I received a lot of criticism. Ginny would support my views and remind me that a whole other profession - psychology - studies people's irrational sides.

Somehow, talking to young students brings you back to reality - it should, anyway.

Physicists have a bias to aspire to be "seers" like Einstein rather than "craftspeople" who do simple and practical research. I have seen that in economics departments. The same must be true to some extent in other departments.

In the longer run and for wide-reaching issues, more creative solutions tend to come from imaginative interdisciplinary collaboration.