Can aging be cured? Hypothesizing that damage to the body accumulates over time, in fairly random ways, researchers and venture capitalists are investigating the mechanisms involved and searching for therapies to prevent or reverse the harms. If their breakthroughs don’t bring true immortality, they could at least vastly extend the healthy years of human life. Other pioneers focus more on a public health approach that emphasizes opportunities to postpone frailty and compress debilitating and degenerative diseases into a relatively short time frame. Are there absolute limits on the human lifespan? How good can things get until the end?