1.1 From Experience to Spacetime
This section sets the metaphysical stage for relativity by introducing doubt as to the reliability of the senses in representing external reality.   Reductionism replaces realism.

Ptolemy and Copernicus constructed two very different conceptual models of the heavens based on essentially the same set of raw sense impressions.
The neo-Tychonian model is a third very different conceptual model of the heavens, which replaced the Ptolemaic system 4 centuries as a geocentric model consistent with testing.
We must choose a level of abstraction deep enough to give a meaningful perspective, but not so deep that it can never be connected to conventional ideas.
Ideas, not experiments.  The Scientific method is founded on the lab as final arbiter of what is true.
If theories can’t be related to experiments(unfalsifiable, says Popper), they are worthless scientifically.   But worthwhile to an ideologue’s agenda.
As an example of a moderately abstract model of experience, we might represent an idealized observer as a linearly ordered sequence of states, each of which is a function of the preceding states and of a set of raw sense impressions from external sources. …
.. by stipulating that the states are functions of the preceding but not the subsequent states we introduce an inherent directional asymmetry to experience, even though the justification for this is far from clear.
Cause and effect is far from clear?   What exp. shows that an effect precedes its cause, either logically or physically?
 ..according to quantum mechanics it actually is not possible to unambiguously map the identities of individual elementary particles (such as electrons) from one event to another (because their wave functions overlap).
An indication of the inadequacy of current QM in describing reality rationally.

Thus the seemingly innocuous assumption of continuous and persistent identities for material objects through time is actually, on some level, demonstrably false.
What observation of reality demos this?
Pair creation and annihilation involve the mutual exchange of existence between an electron/positron pair and 2 photons.   Tracking the existence of individual objects through time may involve such transforms …or reflect limits of the measuring devices   … or of the model of reality.  

… on the macroscopic level, physical objects do seem to maintain individual identities, or at least it is possible to successfully model our sense impressions based on the assumption of persistent identities (because the overlaps between wave functions are negligible),.
So the premise that objects have persistent existence leads to agreement with sense data.
Then  why the conflicting statement just made,” Thus the seemingly innocuous assumption of continuous and persistent identities for material objects through time is actually, on some level, demonstrably false. “ ?
….we have no direct perception of distances between ourselves and the assumed external objects, and even less between one external object and another. We have only our immediate sense impressions, which are understood to be purely local interactions, involving signals of some kind impinging on our senses. We infer from these signals a conceptual model of space and time within which external objects reside and move.
The sense faculties are reliable, when presented with their proper objects. They give a faithful internal representation of external reality.  Without a realism philosophy there is a defective  connection between outside reality and internal comprehension of that reality. In this case mathematics is a worthless tool – it cannot help  in understanding the physical world.
 We have two means of quantifying spatial distances. One is by observing the near coincidence of one or more stable entities (measuring rods) with the interval to be quantified, and the other is to observe the change in the internal state variable as an object of stable speed moves from one end of the interval to the other. Thus we can quantify a spatial interval in terms of some reference spatial interval, or in terms of the associated temporal interval based on some reference state of motion. We identify these references purely by induction based on experience.
So mental manipulation of the data is included, not just the sensory data.  We have confidence in this methodology because predictions of distance based on inferred speed and time interval are correct.
…..we interpret our subjective experience as a one-dimensional temporally-ordered sequence of events,
We experience a 3D representation of reality , not 1D.
Time is a mathematical dimension, but totally different from space dimensions.
In this way we intuitively conceive of time and space as inherently perpendicular dimensions,
This is convenient for mathematical modeling, but where’s the foundation in reality?

but complications arise if we posit that each event along our subjective path resides in, and is an element of, an objective world. If the events along any path are discrete, then we might imagine a simple sequence of discrete "instantaneous worlds"
One difficulty with this arrangement is that it isn't clear how (or whether) these worlds interact with each other.
We say they interact via cause and effect – what is the disproof?

If we regard each "instant" as a complete copy of the spatial universe, separate from every other instant, then there seems to be no definite way to identify an object in one world with "the same" object in another, particularly considering qualitatively identical objects such as electrons.
This is an artificial and unrealistic approach to temporal events – as unrelated sequences of instants, when nature consists off a continuum of actions, broken up into pieces according to independent individual intellects.
….., we could equally well imagine an arrangement in which the "instantaneous worlds" are skewed, so that different individuals encounter them in different orders.
This is an artifact of confusion created by modeling time as equivalent to a 4th spatial dimension.  Accepting this convention leads to further departures from credibility, as in the full-blown theory of relativity.
… we can't even unambiguously define the distance between two worldlines, because it depends on how we correlate the temporal ordering along one line to the temporal ordering along the other.
And this is one clue that the 4D model of nature is invalid.
When we go on to consider multiple observers and objects we can still allow each observer to map his experiences and internal states using the most convenient terms of reference (which will presumably include his own state-index as the temporal coordinate), but now the question arises as to how all these private coordinate systems are related to each other.
An absolute frame of reference for both space and time solves that problem quite nicely…. Why isn’t the absolute system even discussed?
Considering how far removed from our raw sense impressions is our conceptual model of the external world, and how many unjustified assumptions and interpolations are involved in its construction, it’s easy to see why some philosophers have advocated the rejection of all conceptual models.
The rejection of realism in favor of mathematical idealism is the source of this philosophical pessimism.  The problems of relativity can be found in its philosophical dependence on rationalization and separation from experimental testing.

….conceptual models of an objective world have proven (so far) to be indispensable.
Then  why is so much of relativity subjective and speculative?