The White House from Washington, DC · Public domain

An economist whose work on "search and matching" models explained why unemployment and job vacancies can coexist for long stretches — why an economy can have people looking for work and employers looking for workers at the same time. He shared the 2010 Nobel Memorial Prize in Economic Sciences with Dale Mortensen and Christopher Pissarides for that framework, and spent decades advising U.S. policymakers on Social Security. In 2011, after more than a year of Senate opposition, he withdrew his nomination to the Federal Reserve's board of governors — a Nobel laureate in economics blocked from the country's central bank.