(previous previous message)I am not sure, I think I am thinking along the lines of "that it is so unpredictable that even if you measure it multiple times, the probability that it happens cannot be determined even in principle, other than it is nonzero"
(Acuriousmind's message just above) Ok, I guess the reason I am not aware of it is I am new to that term ( I have learnt variance, but covariance is kinda new to me), thus I don't know the term to look it up myself, but thanks, should give that a read