On the Model dependency of astrophysical Observational facts

A recent discussion has led me to try to draw out the distinction between observational "fact" from the (potential house of card) models that best explain that observation.

Attribution of Truth from Fact often neglects the role of the modelling frameworks that underpin any kind of sophisticated observation in physics. Are we identifying facts in those regimes where we are conveniently shining a light?

The most idle of interpretations of a phenomenon may rest on a cascade of intertwined theoretical frameworks and modelling assumptions. The archetype is the interpretative computational edifice used to extract the signal from the noise in 2017 gravitational wave detection experiments.

At the relatively less prosaic level, consider the four simple observations that have relevance in the theory of Big Bang expansion:

1.  spectral lines ( associated to model-postulated elements on a star's surface) are observed to be not in the same position as those elements on an earth bound lab;
2. quasars and distant galaxies, as determined by the Cosmological distance ladder to be more distant by many distinct and partially overlapping inferential measuring tool parallax, laser, Hertzprung Russell diagram spectrum matching, Cepheids where it appears that Cosmological redshifts are proportionally larger than nearer visible objects.
3. the sky is not full of star light- Olber's paradox.
4. the CMBR is 2.6K

Roughly these are best explained by a collection of intertwined theories:

• Quantum mechanical (QM) description of atomic line spectra whereby quanta of light through E=hc/l moving up (timelessly?!) through a gravitational potential have a longer associated wavelengths,thus marking off longer time intervals. This is explained by General Relativity (GR), through both its  "clock" redshift 

(http://slideplayer.com/slide/7101373/ )as well as a distinct different (and significantly larger) Cosmological expansion redshift. The theory leans on theories of stable Star formation and their subsequent generational history.

• there was a super-luminal spatial expansion (probably at early time inflation) which has causally disconnected our vantage (as well as all others to their) point from light sources beyond a horizon. This effectively red shifted all the photon's energy away. GR with Cosmological constant assuming a perfect fluid energy-momentum source with inflation period explains delivering a Cosmological Redshift with increasingly accelerated expansion.

hyperphysics

• thermal radiation from the first decoupling of fermions and one of its mediating bosons- the photon. QM and Statistical Mechanics fits Data to a Plank black body distribution curve with the microwaves observed now.

http://www.astro.ucla.edu/

Any nascent theory in which observed "red shifts" are accounted for wholly by the "clock red shift" rather than the Cosmological one (or as well) have to tick all the other boxes and a lot more..

You could envisage the earliest galaxies/quasars being so dense as to generate huge clock redshifts so cosmological expansion is not needed, but you need a new model of stable star and galaxy formation to back up such unaccounted for densities. How this helps in explaining the other effects I cannot see.


Consider the natural unit system and Dirac's large number hypothesis.

thespectrumofriemannium
You could also envisage either planks constant, h or Newton's constant G being scalar field so that the following constants are number fields and not constant at all.

We have the simplest scalar-tensor theory extension of Einstein theory the Brans-Dicke-Dirac theory.

But you have got to hope that such such tweaks here don't poke holes over there. There is evidence that the higher multipole moments that these scalar-tensor theories predict in gravitational waves was not present in the 2017 observations.

A more fruitful route to uncovering the theory that the folks who are actually prepared to do the hard work but might just have missed (our amateur scientist motives after all) is to work through the house of card assumptions on which astrophysics is built. After all we cannot all scrutinise everything ourselves so we believe in the peer process to deliver the solid frameworks that will scaffold off our next ideas. The cosmic Distance ladder with its use of spectroscopy, statistical methods and intricate assumptions about the stability of stars within a framework of Classical MagnetoHydrodynamics is a candidate house of cards asking to fold.

Virial's Theorem can be unwittingly misapplied to systems that are in fact unbound. Indeed either possessing multitudes of unaccounted internal degrees of freedom through spin and/or the presence of an unattributed dark matter or through a miscalculation of its age and thus its stability.

Belief at one level, is a mental representation of an attitude positively oriented towards the likelihood of something being true. The Greeks give us two related concepts of: pistis referring to "trust" and "confidence", while doxa to "opinion" and "acceptance" from which the English word "orthodoxy" is derived. Their are a great deal of orthodoxies in Astrophysics up for debate.