Pier Stefano Corasaniti wrote:Cosmology is indeed matter of consistency and moving something there implies moving things somewhere else. This is true for the Standard Cosmological paradigm and it is true for any other paradigm you can imagine, "domain universe" included.
So far so good.
Pier Stefano Corasaniti wrote:As you suggest if you want no acceleration from SN and flat universe
As pointed out above, flatness is a conclusion based on an interpretation of the data under a set of assumptions, some of which are invalidated by the presence of domain boundaries.
Pier Stefano Corasaniti wrote:you need to reintrepret the CMB as a non-cosmic background
Not quite. You need to take into consideration that it kept interacting with domain boundaries long after it's conventionally assumed to have decoupled. So it's cosmological, but post-processed in a way which isn't considered in the concordance model.
Pier Stefano Corasaniti wrote:Then is matter of choosing which is the simplest "sensical" scenario which is able to account for the majority of the observations with the minimal effort, sort of application of the usual "Occam razor".
This is incorrect, and a serious misrepresentation of Occam's razor. The history of science is full of beautiful models which could explain *almost* everything, but which nevertheless had to be discarded because of failure to accomodate a crucial observation. Speaking of the CMB, 19th century physicists had an enormously successful theoretical framework which could explain *almost* everything - but resulted in ultraviolet disaster when applied to black-body radiation, ushering in quantum mechanics. Advance to the 1980s and find high energy theorists celebrating the beauty of SU(5) Grand Unified Theory, apparently capable of explaining *all* known physics (except for GR) based on a single compact group - only to discard this extremely compelling model when patient observation of giant water tanks failed to turn up the proton decays predicted by it. Just one crucial observation was all it took.
In the case at hand, the concordance model of cosmology, Penrose has pointed out that there is a crucial contradiction between it and the standard model of fundamental physics. The latter has been confirmed to an excruciating level of precision over several decades. Cosmology is only now beginning to approach a level where it's possible to make precision tests; the concordance model is called that exactly because speaking of the "standard" model, as you incorrectly do, would imply that it's on a par with the standard model of fundamental physics. It most definitely is not. By Occam's razor, when the two models are in conflict, the one to question first is the concordance model.
[Long list of known properties of the concordance model snipped, since it appears to be presented based only on the misunderstanding that the CMB would cease to be cosmological in the presence of domain boundaries.]
Pier Stefano Corasaniti wrote:shall we talk about abundances of the light elements, BBN and limits from astrophysical observations and abundaces in early type stars? or the baryon fraction from cluster...
Only if you can come up with a good argument as to why they would be affected by the presence of domain boundaries.
Pier Stefano Corasaniti wrote:Unfortunately what you are proposing is not a new paradigm, it is just an alternative explanation for only one particular "problem", and when asked about consistency with the rest of cosmological observations this explanation does not tell anything
This is incorrect. On the contrary, it is the concordance model that has a Very Big Problem, at least on the level of proton decay for SU(5) GUT, which needs to be dealt with.
So let's hear it: what's your explanation for the evident lack of readily visible anisotropies in the light reaching us now from sources which haven't been in causal contact since before the electroweak phase transition? What do you do, give up locality and turn all of physics back to the nineteenth century? I don't think so. Give up the standard model of fundamental physics, turning back the clock to the mid-1960s and throwing away all experimental confirmation in its favour accumulated since - and also every proposed extension of it, including supersymmetry and superstrings, which all involve spontaneous symmetry breaking in the low energy limit? Again, I don't think so.
Or do you accept that there are in fact so many domain boundaries between us and the (conventionally defined) surface of last scattering that their individual effects are merged into the residual luminosity distributions presented in my paper? Compared to giving up locality or all post-1960 fundamental physics, this doesn't seem like such a bad option to me.
Pier Stefano Corasaniti wrote:so as you said one is left with working everything again but only inventing another ad hoc mechanism for each of the remaining observations.
This is again incorrect. I have proposed no "ad hoc mechanism". On the contrary, the domain picture emerges from the combination of big bang and standard model of fundamental physics whether we like it or not - it is in fact nothing more than the Kibble mechanism (known for decades and one of the main reasons why inflation was invented, to dilute away topologically stable GUT-scale defects) minus topological stability.
Pier Stefano Corasaniti wrote:My tumb rule is that before starting this game one should always remember that Occam razor is a really sharp one and the tumb can get easily cut.
I fully agree. Watch that thumb of yours. ;)