What is the origin of the word 'abracadabra'? Abracadabra was a magical formula - or incantation - used by a wide assortment of sects in the second century to invoke the aid of benevolent spirits to ward off disease and affliction.
It is supposed to be derived from, or similar in origin to, 'abraxas', a word highly significant of the Supreme Power, which was engraved on gems and amulets or was variously worn as a protective charm.
Handed down through the Middle Ages, abracadabra gradually lost its occult significance, and its meaning was extended to cover any hocus-pocus.
Since radiocarbon dating is only effective for fossils less than 45,000 years old, how can palaeontologists say some specimens are millions or even billions of years old? Numerous scientific methods are used to find the age of fossils. Some measure radioactivity to estimate age. Radiocarbon or carbon-14 dating is the most well-known test.
For older fossils, palaeontologists test surrounding rocks for various combinations of radioactive elements which have a much slower rate of decay than radiocarbon. Potassium 40, for example, has a half- life of 1.3 billion years. It decays into calcium 40 and argon 40. Since argon is relatively scarce on Earth, it is easier to measure than calcium.
Rocks can be dated by measuring the ratio of radioactive argon to radioactive potassium. Using this method, some meteorites have been dated to 4.5 billion years old.
