It has been reported in the "Khutba al-Muttaqin" by Ali, peace be on him, the following words:

"There is a fixed hour for each death that it will not exceed it, and a cause which does not change"

It means there is a time for death that Allah knows, and no one can anticipate or postpone it. On the contrary, human knowledge increases and decreases and it is subject to changes. Such changes are unexpected events to man  but nothing effects the infinite knowledge of Allah. 

With prayers for your success.