A faint line from argon shows in the spectrum of the doomed star Eta Carinae.Eta Carinae has a mass of more than 100 Earth suns. The first hint of its existence came from English scientist Sir Henry Cavendish as far back as 1785.
William Ramsay discovered argon when he first saw its spectrum and realized it matched no other’s. Cavendish was unhappy that so little was known about air.
He was particularly unhappy about the lack of information about the fraction of air (the majority) which was not oxygen.
Climate records from a Japanese lake are set to improve the accuracy of the dating technique, which could help to shed light on archaeological mysteries such as why Neanderthals became extinct.
Carbon dating is used to work out the age of organic material — in effect, any living thing.
Avant la découverte de la radioactivité, Lord Kelvin avait estimé l'âge de la Terre à quelque vingt millions d'années, en supposant que la seule source d'énergie capable de s'opposer au refroidissement était la chaleur résiduelle, initialement produite par la formation de la Terre.
Un âge de seulement quelques dizaines de millions d'années fut considéré beaucoup trop court par les géologues, et un débat assez virulent s'ensuivit entre la communauté des géologues et celle des physiciens.
He then added additional oxygen until all the nitrogen had reacted. Cavendish used aqueous sodium hydroxide to remove them from the apparatus.
[This would also, of course, have removed any carbon dioxide that was present.] He removed the remaining oxygen using potassium polysulfides. Cavendish wrote that this bubble “was not more than one hundred and twentieth of the bulk of the phlostigated air [nitrogen].” So, Cavendish is saying that air is at least 99.3 percent nitrogen/oxygen/carbon dioxide with a maximum 0.7 percent of something else.
Beta particles originate in the nucleus, presumably by breakdown of a neutron into its proton-electron components.