Multiple realities
(covers information from several alternate timelines)
For the similarly-titled Star Trek: The Next Generation episode, please see Half a Life (episode).
For its podcast episode, please see Half a Life (podcast).
A half-life was the amount of time it took for an isotope's radioactivity to decay into half the amount.
Tritium had a short half-life. (SNW: "Tomorrow and Tomorrow and Tomorrow")
Veridium's half-life was less than seventy hours. (VOY: "Riddles")
Iridium had a short half-life. In 2377, Tuvok reasoned that Gar would have had to acquire the iridium he traded with USS Voyager within a three light year radius of where they met, and therefore, they should be able to find him. (VOY: "Critical Care")