radioactive clock

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• nuclear clock — ▪ physics       frequency standard (not useful for ordinary timekeeping) based on the extremely sharp frequency of the gamma (gamma ray) emission (electromagnetic radiation arising from radioactive decay) and absorption in certain atomic nuclei,… …   Universalium

• helium dating — Method of dating that depends on the production of helium during the decay of radioactive isotopes of uranium and thorium. Because of this decay, the helium content of any mineral or rock capable of retaining helium will increase during the… …   Universalium

• Nuclear weapon design — The first nuclear weapons, though large, cumbersome and inefficient, provided the basic design building blocks of all future weapons. Here the Gadget device is prepared for the first nuclear test: Trinity. Nuclear weapon designs are physical,… …   Wikipedia

• Radiometric dating — (often called radioactive dating) is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.[1]… …   Wikipedia

• Caesium — xenon ← caesium → barium Rb ↑ Cs ↓ Fr …   Wikipedia

• technology, history of — Introduction       the development over time of systematic techniques for making and doing things. The term technology, a combination of the Greek technē, “art, craft,” with logos, “word, speech,” meant in Greece a discourse on the arts, both… …   Universalium

• Radiocarbon dating — (sometimes simply known as carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon 14 (14C) to estimate the age of carbon bearing materials up to about 58,000 to 62,000 years.[1] Raw, i.e. uncalibrated …   Wikipedia

• radiation — radiational, adj. /ray dee ay sheuhn/, n. 1. Physics. a. the process in which energy is emitted as particles or waves. b. the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and… …   Universalium

• List of fictitious films — This is a list of fictitious films that have been referenced in various forms of media. These films are usually part of the storyline in a movie or television episode, usually either as a prop or as a recurring theme visited throughout, such as… …   Wikipedia

• Strontium — (pronEng|ˈstrɒntiəm, ) is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when… …   Wikipedia

• evolution — evolutional, adj. evolutionally, adv. /ev euh looh sheuhn/ or, esp. Brit., /ee veuh /, n. 1. any process of formation or growth; development: the evolution of a language; the evolution of the airplane. 2. a product of such development; something… …   Universalium