Word: radiocarbon
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Ever since its development in the 1940s, radiocarbon dating has been a vital tool for historians and paleontologists trying to pinpoint the ages of everything from ancient animal bones to prehistoric human settlements to Egyptian mummies. By measuring the decay of the natural radioactive isotope carbon 14, which almost all organisms ingest while they are alive, scientists can estimate how long it has been since an animal or plant died...
...first, archaeologists thought that the find was related to a 6th century A.D. building, similar in structure, at nearby Doon Hill, in East Lothian. But radiocarbon dating of the wood at Balbridie Farm indicates that the timber was felled as long ago as 4000 B.C. The composition and style of pottery shards found in one of the pestholes are characteristic of that time. Thus the hall was apparently built at least 1,000 years before Stonehenge, and is several centuries older than a small timber hutch in County Tyrone, Northern Ireland, that has until now been regarded as the most...
...believes the direct measurement system, which requires as little as one-hundredth of the material needed for current dating tests, will eventually win wide acceptance. He and his colleagues have accurately determined some test samples to be 70,000 years old. With more work, they believe, they can push radiocarbon dating of tiny samples back to 100,000 years...
Some studies at the center are much more mundane. Jack Eddy, a visiting scientist at the Center, has shown how the amount of radioactive carbon in tree rings can be related to sunspots. Increased solar activity leads to warmer climates, Eddy says, raising the radiocarbon content of the rings. Another group of astronomers, working with radio telescopes designed to detect water vapor in remote parts of our own galaxy, found they could also use the radio telescope to measure the amount of water vapor in the earth's atmosphere. The method proved cheaper and more accurate than previous techniques, like...
...were given one wish by a genie," writes Gerald Hawkins, "I would ask for a time machine to go back to dates like 1776, 1066 and 2000 B.C." But in a sense Hawkins has already had his wish-with the help of aerial surveys, radiocarbon dating and a computer. As a Boston University astronomer, he has been able to program the orbits of the sun and moon, then order a computer to trace them backward in time...