Mark Buchanan

Two years after the frightening spring day when the Dow Jones Industrial Average lost and regained about 600 points in a matter of minutes, we still don’t really know why. This is a problem, because it means something similar -- or worse -- could happen again.

Almost five years after a financial crash nearly thrust the world into depression, a peculiar paradigm still dominates economic thought.

The futurist Ray Kurzweil has famously predicted that humanity is approaching a “singularity,” a fateful moment when our technology becomes smarter than us and able to learn faster than we can, when it becomes the principal creator of new technologies and machines race far ahead of us. Humans may effectively fall out of the loop -- a species demoted, if not eliminated.

The aftermath of the Lehman Brothers Holdings Inc. bankruptcy in 2008 was a scary time: One measure of stock-market volatility, known as the VIX or the “fear index,” reached a peak daily closing price of more than 80, compared with about 18 today. Scarier is the knowledge that we’ll be there again sometime. That’s how markets go: Unexpected chaos is the rule.

It’s an iconic image: the professor of physics, wild hair, Einstein-like, standing before a chalkboard covered with arcane equations. It could be Einstein himself, the scribbled mathematics describing his theory of relativity and the link between mass and energy, E=MC2.

The possible collapse of the European monetary union, at least in its current form, brings home the truth that there’s little in economics that is certain. We’re again “thinking the unthinkable,” as we were a few years ago when we suddenly realized that financial engineering hadn’t banished financial crises, and that 70 years of relative stability since the Great Depression didn’t guarantee a thing.

The European sovereign debt crisis stands as the latest in a long line of similar crises. Argentina in 2001. Russia in 1998. Mexico in 1994. The list goes back into history. Debt crises are about as natural as earthquakes, but this time there is something different -- and possibly more dangerous.

In the midst of great macroeconomic uncertainty, the Nobel Prize in Economics has been awarded to Thomas Sargent, of New York University, and Christopher Sims, of Princeton University, for work on “empirical macroeconomics.” Sargent and Sims are both superb scholars whose work has molded macroeconomics. They helped destroy the false certainty of an older Keynesian orthodoxy, and did their best to build more robust tools that shed light on public policy over the business cycle.

Last year, when the U.S. Securities and Exchange Commission came out with its final report on the flash crash, the stomach-churning event of May 6, 2010, that wiped $1 trillion of value from the markets in less than 30 minutes, it never managed to explain why the episode happened.

Efficiency is generally a good thing. We don’t want our car engines to waste fuel through internal friction or the heat from our furnaces to slip out the window.