For decades, radiocarbon dating has been a way for scientists to get a rough picture of when once-living stuff lived.The method has been revolutionary and remains one of the most commonly used dating methods to study the past. Pearson, an assistant professor of dendrochronology at the University of Arizona, studies the past lives of trees to better understand the history of civilizations."It can get us to within 20, 50, 100 years or so of dating accuracy." On the scale of the universe, 20, 50 or even 100 years is, for all intents and purposes, nothing. Our galaxy, the Milky Way, is slightly younger, at 13.2 billion years old.
In other words, life in the universe moves inconceivably slowly.
But for individual humans—and entire civilizations—it does not.
In its most conventional form, dendrochronology works like this. They have no bias, and they have no political agenda; they just stand at locations all over the world," says Charlotte Pearson, an assistant professor of dendrochronology at the UA, studies samples under a microscope.
A contemporary tree—that is, a tree that was either just cut down or still living—can tell you not just how many years it has lived, but which years in which it lived. Credit: credit: Mari Cleven But what if the wood is older?
Indeed, the "Secret Of The Southwest" was revealed.
An Isotope Called Carbon-14 But alas, pattern-matching in order to date when a tree was cut isn't always possible.A decade after Douglass's big discovery, two Berkeley scientists took the first step towards an alternative way to date floating chronologies and indeed any other "once-living" thing. Also known as radiocarbon, carbon-14 is a radioactive isotope of carbon with an atomic nucleus of six protons and eight neutrons. They discovered its half-life, or the time it takes for its radioactivity to fall by half once the living thing dies, is 5,730 years (give or take 40).It's unusually long and consistent half-life made it great for dating.The first single-celled organisms on Earth did not appear until about a billion years later.Dinosaurs did not appear until 230 million years ago, and ruled the planet for 135 million years."We can look at the tree rings as a timeline and connect with people that lived in the past, and I think that gives us more of a sense of who we are, but also a sense of where we're going and perhaps ways to deal with some of the issues that we might collectively face.