"So your four dimensional universe reifies time and space in a way that claims that everything that has ever existed or ever will exist are 'equally real.' "
Are living dinosaurs and human colonies on Mars “real and present” in some “slice” of “four dimensional spacetime” (a concept) as seen from another frame of reference with each frame of reference having its own 'now' and its own reality?
One of the consequences of special relativity is that time is not absolute. Not only do clocks in motion disagree on what the rate of time passing is, but inertial coordinate system disagree on what events have the same coordinate time if their positions are distinct from one another. This is called the relativity of simultaneity.
Regarding the first sentence, you have never addressed the ontological challenge to the reification of time, making “something” of it besides the obvious “elapsed time” as things move from one point in space to another.
We all know that clocks slow down relative to each other as above yet the challenge to time reification still stands unanswered. The physical process of oscillation slows down in clocks at higher speeds relative to those at lower speeds or in lower gravity fields (higher elevation.)
But what is "time," that "it" slows down?
You never commented on the quote above about “coordinate systems” like 4-D spacetime being in “conceptual space” as distinguished from actual objects moving through space as time passes. Rather, the conceptual coalescence of space and time are taken for granted.
I did not understand why you said, “Ignoring two dimensions of space, we can establish the inertial coordinate system S ...”
Why ignore two dimensions of space?
Space is three dimensional. Time elapses as things move. Call it a fourth dimension but "it" is not an entity combined with space (ontologically speaking.) Everything you wrote beyond the above quote was math. I already said that I am not a mathematician, but I do understand the difference between a coordinate system and the “real world” which it “maps.”
A couple of missing links from yesterday's post:
Stanford Encyclopedia of Philosophy on "Time": http://plato.stanford.edu/entries/time/
The Reference Frame: Presentism vs Eternalismhttp://motls.blogspot.com/2008/05/presenti...eternalism.html
Finally, "real to me" and "real to them" puts priority on frame of reference *as Reality.* Philosophically, beyond that dictum of relativity, things are as they are in the "real world" regardless of frame of reference. "Length contraction" (as per the other thread) is a good example. It is up to science to figure out whether, for instance, earth is a very oblate spheroid, as "seen" from very high speed, or nearly spherical as "seen" from living on it or from orbit around it.
"What is solipsism is to deny that the other person is real. What violates the principle of relativity is to claim that the other person is real and still deny that other persons reality is as real as your reality, all things being equal, mutatis mutandis
The above statement about "the 'real world' regardless of frame of reference..." does not deny anyone's reality. It elevates "reality" beyond how it is *observed* from different frames of reference. This point has never been addressed here.
I put it to you as I did to synthsin75: Is the flattened earth "equally valid" with the spherical earth just because "another person" flying by at very high speed might see it that way... and we must 'respect his reality'? No.
The philosophy of science called realism says, as above, that the world IS as it IS, not as different frames of reference *see* it. Accordingly, IS means the Present, and the Present IS the Present everywhere, transcending relativity's reification of space, time and spacetime.
Again, please address presentism vs eternalism, the latter of which describes a "block universe" where past, present and future are somehow all Present (depending on frame of reference.) Do you actually believe that?