Since there exist in this four dimensional structure [space-time] no longer any sections which represent "now" objectively, the concepts of happening and becoming are indeed not completely suspended, but yet complicated. It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence.

Even with quite slow relative velocities, significant differences in time-ordering will occur for events at great distances. Imagine two people walking slowly past each other in the street

Fig. 5.22. Two people A and B walk slowly past each other, but they have differing views as to whether the Andromedean space fleet had been launched at the moment that they pass each other. (p. 201)


According to relativity, there is not really such a thing as the `now` at all. The closest that we get to such a concept is an observer`s `simultaneous space` in space-time, as depicted in Figure 5.21, p. 200, but that depends on the motion of the observer! The `now` according to one observer would not agree with that of the other. ¹ Concerning two space-time events A and B, one observer U might consider that B belongs to the fixed past and A to the uncertain future, while for a second observer V, it could be A that belongs to the fixed past and B to the uncertain future! (See Fig. 7.1). We cannot meaningfully assert that either one of the events A and B remains uncertain, so long as the other is definite.


Fig. 7.1. Can time actually `flow`? To observer U, B can be in the `fixed` past while A lies yet in the `uncertain` future. Observer V holds the contrary view!


Recall the discussion on p. 201 and Fig. 5.22. Two people pass each other on the street; and according to one of the two people, an Andromodean space fleet has already set off on its journey, while to the other, the decision as to whether or not the journey will actually take place has not yet been made. How can there still be some uncertainty as to the outcome of that decision? If to either person the decision has already been made, then surely there cannot be any uncertainty. The launching of the space fleet is an inevitability. In fact neither of the people can yet know of the launching of the space fleet. They can know only later, when telescopic observations from earth reveal that the fleet is indeed on ist way. Then they can hark back to that chance encounter, and come to the conclusion that at that time, according to one of them, the decision lay in the uncertain future, while to the other, it lay in the certain past. Was there then any uncertainty about the future? Or was the future of bothpeople already `fixed`?

It begins to seem that if anything is definite at all, then the entire space-time must indeed be definite! There can be no `uncertain` future. The whole space-time must be fixed, without any scope for uncertainty. Indeed, this seems to have been Einstein`s own conclusion (cf. Pais 1982, p. 444). Moreover, there is no flow of time at all. We have just `space-time`--- and no scope at all for a future whose domain is being inexorably encroached upon by a determined past!

We could still imagine that there is a set of laws that determines events completely for some supernatural being, who could observe the present state of the universe without disturbing it. However, such models of the universe are not of much interest to us mortals. It seems better to employ the principle known as Occam's razor and cut out all the features of the theory which cannot be observed.

The widespread view that relativity completely confounds past and future is completely wrong. However, in contrast to relative past and future, absolute past and future are no longer separated from each other by an infinitely narrow present. The thought imposes itself that one can perhaps call the neutral zone absolute present, but I on my own part would not consider this a happy designation. It is far more fittingly characterized with the designation “Absolute elsewhere.” We have as a matter of fact eliminated the now-lines and have limited the present (now) to here=now in the absolute world of the present. [...]

Events in the absolute future are not absolutely elsewhere. It would be possible for an observer to depart from here=now and to arrive on time in order to be present at the event in question, for the speed needed for this is less than the speed of light; relative to such an observer’s world structure, the event would be here. But no observer is able to be present at an event in the neutral zone belonging to his here=now, since the speed needed for this would be to great. The event is thus not here for any observer who proceeds from here=now, here,consequently it is absolutely elsewhere. [...]