I suspected that very soon the astrophysicists/cosmologists among us would
weigh in on this subject; that is one reason why I was hesitant to raise it
in the first place. So let me confess my paltry qualifications up front.
I studied special relativity (STR) formally and used a bit of that when I
worked on orbital mechanics stuff in the Air Force. I have studied GTR
informally, but you will soon lose me in tensor calculus. :^) But I am
quite conversant with the treatments of time in general as well as STR and
GTR in philosophy of science. And this may be the problem!
Many philosophers of science ask different questions about scientific
theories, and consequently give different answers, than practicing
scientists do. And many of us will claim that both the limits and the
interpretations of scientific theories are a philosophical matter, not a
scientific matter (using philosophy broadly here to include theology). I
realize that this is an audacious claim to make in a group of practicing
scientists, and in my several years on this listserv I have not seen this
question addressed. (Perhaps this could become the subject of another
interesting discussion thread.) So that's where I'm coming from. Now to
your post:
At 10:09 AM 11/11/1997 -0500, Moorad Alexanian wrote:
>
>Dear Garry and Jan,
>
>I believe that how God views us is useful in the discussion of some issues,
>in particular, the question of God knowing what we are going to do in the
>future. In physics we can draw diagrams of spacetime where a point
>constitutes an event occurring at a particular position in space and at a
>particular time. The world curve of a sequence of events will depict what is
>the spatiotemporal behavior of something. Therefore, the whole lifetime of a
>person can be denoted by a curve beginning with the point of conception and
>ending in the death of the individual. That is to say, all the actions of
>the individual are there to be seen yet the individual may not loose his/her
>ability to decide for himself/herself. For God the whole lifetime of people
>is like an eternal Now. Of course, there is more knowledge of God that the
>mere spacetime. He knows us before conception and after death. The analogy,
>of course, breaks down but it is still useful. I recall reading C.S. Lewis
>on these points and I found his writing useful. In particular, when he said
>that the reason that God knows what you are going to do tomorrow is that He
>already saw you do it. That view is consistent with seeing the whole of the
>path in the spacetime diagram.
My main problem with this is that the possibility of describing the
evolution of a physical system in the future (ignoring, for the moment,
questions about how do define "now") does not mean those future points
actually exist. I can plot the trajectory of a projectile, but even though
I can plot (or calculate) its impact point, the impact is not *real* in any
sense until the projectile actually comes down! The fact that time-like
world curves can be ploted (or it is alleged that they can be plotted) in
4-space does not mean that the "future" of those curves (all points later
than "now") actually exist, or are real.
I think (and I do say this with considerable humility--and trepidation)
that physicists who try to give a realist interpretation to such things are
forgetting that solutions to mathematical models are no more than
theoretical entities. If I solve a simple quadratic equation to determine
the length of the board I need to cut for the sloping roof of a dog house
I'm building, I don't have to wonder if I should cut it at 28" or
*negative* 28". The latter is an artifact of the mathematical model, but
corresponds to no physical reality; it is physically unrealistic. Of
course you and other cosmologists know this. But why then should you think
that all solutions to, say, Einstein's field equations are physically
realistic, or that if you can solve (theoretically) for complete world
curves in space-time, that the segment of the curves which are later than
"now" correspond to anything real?
(Whew, after writing that, I feel like I've painted a target on my back and
invited all astrophysicists to jump on me!)
The upshot is I disagree significantly with what you wrote about God
knowing the future in virtue of knowing the entire world curve of an
individual.
Interestingly, this view in essence is not new. Boethius (ca. 500) and
Thomas Aquinas (ca. 1200) both use the image of a watchman on top of a
mountain or in a tower observing a line of travellers below. The
travellers represent moments in time; they each pass a fixed point (="now")
successively, but the entire line (="all moments of time") are equally
present to the watchman (=God). But as others have shown conclusively,
this image only works if the future points *actually already exist.* But
if time is dynamic, if temporal "becoming" is real, then these
illustrations break down, and so do any contemporary analogues which ground
God's foreknowledge in the exsitence in space-time of complete world lines
of individuals.
Note: I am not denying God's foreknowledge. I merely maintain that God
does not know the future because it actually exists. For I maintain that
there is an ontological assymetry between past and present, on one hand,
and future on the other; the future does not exist. So God's knowledge of
the future is grounded differently.
Don Page raised some interesting and important objections to some of what I
jsut wrote, so I will have to respond to that in another post. But
teaching calls...
Garry