[Suppose you have a slice through the block of cement of spacetime, corresponding to a time, say, of six in the evening in London on 14 April 2016. "General relativity says that if I know the conditions in this instant, I can predict the entire future because the laws [of physics that govern this chunk of spacetime] are deterministic," says Cortês. "The future is entirely written, it's just not accessible to us [inside the block] at this point."]

The answer is simple, since you cannot predict the future (or you might run a fortuneteller business), so you are wrong with the above statement.....It is just that simple