Most of us, of course, think we know what a depression looks like. Open a history book and the images will be familiar: mobs at banks and lines at soup kitchens, stockbrokers in suits selling apples on the street, families piled with all their belongings into jalopies. Families scrimp on coffee and flour and sugar, rinsing off tinfoil to reuse it and re-mending their pants and dresses. A desperate government mobilizes legions of the unemployed to build bridges and airports, to blaze trails in national forests, to put on traveling plays and paint social-realist murals.

Today, however, whatever a depression would look like, that's not it. We are separated from the 1930s by decades of profound economic, technological, and political change, and a modern landscape of scarcity would reflect that.

What, then, would we see instead? And how would we even know a depression had started?