Tritium is also an important fuel for controlled nuclear fusion reactions.
The existence of tritium was first predicted in the late 1920s by Walter Russell, using his "spiral" periodic table.
It was produced in 1934 from deuterium, another isotope of hydrogen, by Ernest Rutherford, working with Mark Oliphant and Paul Harteck.
Rutherford, however, was unable to isolate tritium, a job that was left to Luis Alvarez and Robert Cornog, who correctly deduced that the substance was radioactive. Libby discovered that tritium could be used for dating water, and therefore wine.
The properties of tritium make it useful for various applications.
For instance, it is used in some self-illuminating watches, compasses, key chains, and gun sights for firearms.