The surveillance cameras and electronic locks are the only hints that a visitor has reached the border of a scientific frontier. Behind these laboratory doors a few blocks from Columbia University in Manhattan is a research enterprise quarantined by federal law because, for many people, it poses a moral hazard.
Inside, a technician adjusts a microscope and a cluster of human embryonic stem cells — with the potential to develop into the body’s many cell types — springs into view, blurred only by politics, ethics disputes and conflicting beliefs about the beginnings of life.