Wow, you are stupid.
Three observers may disagree on the temporal order of events. This is relative simultaneity.
What Greene is saying is that these three different planes of simultaneity are equivalent to slicing a loaf of bread at three different angles. The totality of existence, then, cannot be any individual plane of simultaneity, but rather ALL planes of simultaneity; i.e., the entire loaf of bread — from which it follows that the future is as fixed as the past. The indexical that we call NOW is a plane of simultaneity that slices an extant 4d reality at a particular angle. Others will slice the bread at a different angle.
In a sense, yes, someone could “see” my future before it happens — NOT in the sense of violating causality, but in the following sense that was originally mooted by Einstein in his train thought experiment: The ground observer sees lighting flashes hit the back and front of the train simultaneously. However, for the observer moving in the train, the flash at the front of the train happens first, and flash at the back happens later. This just IS relative simultaneity.
Now, in a sense, ground observer has “seen” train observer’s future — the train observer will, without fail, observe the flash at the back of the train, but sequentially, after the flash at the front, whereas the ground observer saw the flashes simultaneously. There is NO violation of causality here; however, the train observer’s future is fixed, even though he/she has not experienced it yet.