As an economist who studies health care, I find it hard to know whether to welcome or fear new technology. Surgeons can replace a heart valve with a plastic and metal one that unfolds once threaded through arteries—repairs that used to be made by cracking open the chest. Customized cancer drugs hold the promise of making fatal diseases treatable. At the same time, it's depressingly common to hear projections of fiscal Armageddon as health-care spending drags the U.S. federal government into debt and wipes out any wage growth for the average American. Even a recent slowdown in spending growth simply postpones the inevitable date when Medicare goes bankrupt.