Dating materials using radioactive isotopes reality show internet dating

The following summaries offer a quick introduction to some of the dating techniques researchers have been using to explore and reconstruct our planet's past, from 4.5 billion years ago to the present.

Kate Wong RADIOACTIVE ISOTOPES The premise behind techniques involving the use of radioactive isotopes is straightforward.

Although Boltwood's resulting estimates for things like the age of Earthwhich he placed at around 2.2 billion yearshave since been significantly revised, he indicated correctly that our planet was far older than people had imagined possible.

In the decades that followed, scientists made important new discoveries about the structure and behavior of atoms, and they refined their existing dating techniques.

ANCIENT ARTWORK, such as this Chinese horse, can be evaluated using thermoluminescence.

Indeed, just last month researchers described a fossil that pushes the origins of key mammal features back some 45 million years.

Because of that condition, scientists say, the technique is well suited to dating meteoritic impacts, fire-treated stones used by early humans, cooking hearths and old ceramics.

Somewhat similar to thermoluminescence, electron spin resonance (ESR) dates crystals, too (although these are found in shells and enamel.) Unlike thermoluminescence, however, this method counts the number of "unpaired spins" of electrons trapped in the crystal, instead of freeing them.

Geologists, paleontologists and archaeologists have pieced together a fairly detailed account of how Earth and its inhabitants evolved.

But just how do researchers determine the ages of the materials they unearth?

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