Question of being in relativistic space-time

If Einsteinian relativity physics is to be taken seriously -- and it is within the scientific community-establishment taken unquestionably so, because science's only criterion of truth is experimental verification -- then this physics confronts us with weird consequences.

I've already addressed one of them in my recent post on mental acts.

What about the question of being posed within relativistic space-time? For simplicity, I'll consider here only the flat Minkowskian space-time of special relativity, but similar thoughts apply mutatis mutandis to general relativity with its curved Riemannian space-time. Note that each observer-subject in relativity physics has its own reference frame, that is, its own space-time manifold.

In relativity physics there is no longer any 3D-Euclidean space (Where specified as (x,y,z)) with an add-on 1D-temporal line (When specified as t) to count/measure time absolutely within the 3D-space. This was the situation in Newtonian mechanics, for time was its own dimension and hence absolute, a single clock for the entire universe. In relativity, time becomes relative to the absolute movement of light (or, more, generally, electromagnetic radiation) as received by an observer-subject, thus spatialized and tied to the three spatial dimensions, so that the relativistic physicist now speaks only of 4D-events in space-time (x,y,z,t). The 'distance' between space-time events is now neither purely spatial as measured Euclideanly as
d^2 = x^2+y^2+z^2, 
the square of the distance is the 'Pythagorean' sum of the squares of the 3 dimensionals,
nor is it purely temporal as measured by
d^2=t^2,
 i.e. a time-interval given by the formula, the square of the temporal distance is the square of t.

How, then, is 'distance' between events measured in flat relativistic space-time? It is measured by the so-called 'metric' on the Minkowskian space-time manifold as defined by the space-time distance formula:
s^2=(x^2+y^2+z^2) - t^2 = d^2 - t^2,
that is in words, the squared space-time distance between events is the difference between squared spatial distance and the squared temporal interval ('distance'). This is weird enough, but it's the way mathematical relativity physics proceeds. In general relativity, the metric on the space-time manifold just gets (much) more complicated and harder to handle in the (tensor-differential) equations.

What are some consequences of this conception of distance between space-time events? One is that there is zero space-time distance between events if and only if the square of their spatial distance is equal to the square of their temporal distance, that is:

0=(x^2+y^2+z^2) - t^2 = d^2 - t^2,
which implies
d^2 = t^2,
so that
d = +/- t,
or in words: the spatial distance is equal to plus or minus the temporal interval-distance.

Let's take a simple example, the Sun in our Earth's solar system. The Sun's distance from Earth is approx. 150 million km, and it takes light approx. 8 minutes to reach the Earth over this spatial distance.

What does it mean for an observer-subject on Earth for the Sun to 'be'? For science it is axiomatic that only that 'is' which can be registered as a signal received sensuously in the here-and-now. Only that which is here-and-now 'is', i.e. exists, for modern science. How does the Sun exist in the observer-subject's here-and-now? Answer: Only if the space-time distance between sun-events and observer-events is zero.
What does that mean?
Events always have the form (x,y,z,t), i.e. (where,when) in space-time.
The Sun's (where,when) has zero space-time distance from the observer's (where,when) if and only if the metric gives zero, that is, the square of the spatial distance 
150^2 km^2 = 8^2 sec.^2.
But this means that for you as observer the Sun only exists in your here-now at either plus eight minutes in your future or at minus eight minutes in your past within your very own Minkowskian reference frame! For you, the Sun only ever will be or was, but never 'is' at your present moment. The eight minutes represent the time it takes for you to receive a light-signal from the Sun, or for you to send a light-signal to the Sun.

If you take the Moon rather than the Sun, the former has an average spatial distance of approx. 384,000 km. from the Earth Since light travels at approx. 300,000 km/s, the Moon is a bit more than one light-second away spatially. Relativistically speaking, the Moon only exists for you observing it on Earth at plus one second in your future or minus one second in your past.

And the Sun and the Moon exist 'simultaneously' for you, the observant receiver of light signals, only separated by roughly plus or minus eight minutes!

You can only ever observe those events whose space-time distance from you is zero or negative:

(x^2+y^2+z^2) - t^2 = d^2 - t^2 <= 0

All those events with positive space-time distance from you:

(x^2+y^2+z^2) - t^2 = d^2 - t^2 > 0

are outside your Minkowskian light-cone, hence cannot reach you, nor you reach them, in your space-time and therefore do not exist for you, never have and never will.

For you as observer-subject, your space-time, here-and-now 'event simultaneity' is an infinite superposition of spatial spheres whose ever-increasing squared spatial distances match your ever-increasing squared times of time future and time past.

Hence relativistic space-time 'simultaneity' is weirder than physicists care to think.
Since in relativity theory, the subject is cast exclusively AS a receiver (or sender) of e-m (or gravitational) signal-information, how can an active mental act by the observer be conceived at all? Only as sending a signal?

Apropos: Today's smug & arrogant mathematico-scientific elite is hell-bent, for instance, on furthering the reach of both relativity theory and quantum mechanics into the human mind (a unified theory of quantum gravity is still sadly lacking). Hence, for example, the famous Sir Roger Penrose is working on a theory of consciousness with a quantum-mechanical core (cf. my recent link to The Life Scientific on BBC4). When you think you're actively thinking, in physical 'reality' you're only surfing on underlying quantum-mechanical 'processes'. You're deluded.

One could pose the question as to whether the flat or curved relativistic space-time of modern mathematical physics is at all existentially liveable for us human beings. Or does it represent a brutal, unliveable truncation of the existential world solely for the sake of gaining mathematically calculable access to it with the aim of mastering and controlling all physical movement/change?

It goes without saying that today's scientists dismiss such questioning out of hand as 'unscientific', 'poetic', mere 'philosophical speculation', 'ridiculous', &c. I have plenty of hard empirical evidence of this evasion. Instead of a genuine, open-minded 'search for truth', I experience savage defence of the status quo.