Classical element to use the term "element (στοιχεῖον, "stoicheion")" in reference to air, fire, earth, and water. The ancient Greek word for element, "stoicheion" (from "stoicheo", "to line up") meant "smallest division (of a sun-dial), a syllable", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed. A similar alphabetic metaphor may be the origin of the equivalent Latin word "elementum" (from which the English word comes), possibly based on the names of the letters 'l', 'm', and 'n', though the validity of this idea is debated. In his "On
Fusion ignition of deuterium and tritium, which are both isotopes of hydrogen, in order to compress the isotopes to a fraction of their original size, and fuse them into helium atoms (releasing neutrons in the process). In January 2012, National Ignition Facility Director Mike Dunne predicted in a Photonics West 2012 plenary talk that ignition would be achieved at NIF by October 2012. However, , NIF is operating at conditions about 1/10 to 1/3 of breakeven. Confusingly, by LLNL definitions, ignition and breakeven occur at the same point, due to specifics of their experiment. Experts believe that achieving fusion ignition is the