ELI5: Explain Like I'm 5
Examples: reciprocal lattice, thorium, static analysis, mass, foreign function interface

Oldest people

Oldest people are people who are really, really old! To be really, really old, you have to have been alive for a really, really long time. That means that you have to have been born a long, long time ago. Scientists study these people to learn more about how long people can live.