Elizabeth I dies and James VI of Scotland accedes to the English throne. Elizabeth I died childless so was succeeded by her cousin, James VI of Scotland, who henceforth assumed the title of James I of England as well.
T minus zero means out of time.. This comes from a countdown convention used in by both the American military and NASA. Generally, it is used when counting down to a major event that will happen at a specific time. Mathematically, T is time, minus whatever amount of time is left until the event happens.
For people new to the subject, a good way to remember what null means is to remember that in terms of information, lack of a value is not the same thing as a value of zero; similarly, lack of an answer is not the same thing as an answer of no.