sol invictus said:
What? Why?
It's true that it was known in the early 1980s that a roughly flat primordial spectrum over some range of scales would probably be consistent with observations, but that's it (and that's why those guys were excited about their results). But inflation predicted something much more specific, only the first rough version of which is in those 1982 papers. By 1996 paper there were many details (like the acoustic peaks), none of which were observed until years later.
This appears to be a gray area. Initially, inflation was needed to account for observed characteristics of the universe like homogeneity, etc. Later, it was realized that a totally homogeneous era could not lead to the structure currently observed --- some inhomogeneity was needed. As I recall, quantum fluctuations were then presented as the likely cause of the primordial lumpiness leading to galaxy formation, etc. Then, a search for inhomogeneities in the CMB ensued -- and were found.
Would there not have to be quantum fluctuations anyway, for galaxies to form, with or without inflation? Are there not other possible explanations for the CMB and its irregularities? It seems that MM's view that aspects of inflation theory are "postdicted" might have some merit.
I'd like to introduce an example from astronomy that shines a bright light on the "
predicted/post-dicted" distinction; I think the only reasonable conclusion one can draw from this example is that such a distinction is pretty close to meaningless, and that if you do wish to try to keep it, you would need to pay extraordinary attention to detail.
Consider "dark matter".
Zwicky introduced the term, in the 1930s, to account for an apparent inconsistency in an analysis he did of the data he obtained on a rich galaxy cluster (Coma). At the time, Zwicky had no reason to introduce 'non-baryonic' as a modifier, nor 'cold'; indeed, it is unlikely either *could* have been applied at the time!
Not long afterwards (or possibly before), Jan Oort (yes, of Oort cloud fame) published evidence for the existence of dark matter in the local region of the Milky Way (i.e. within a few hundred pc of sol); several decades later re-analysis together with far more extensive data showed his conclusion was in error.
In the late 1960s, Rubin (and colleagues) published studies of the rotation curves of some nearby normal spiral galaxies, concluding that these galaxies are embedded in a halo of dark matter.
It took another ~25+ years for compact massive halo objects (MACHOs) to be ruled out as the primary component of this inferred massive halo; sometime around then dark matter began to be seriously considered as being non-baryonic (and cold).
Sometime after the first decent x-ray band data on rich galactic clusters became available, the existence of an essentially thermal, hot, diffuse IGM was confirmed; the estimated mass of such was, and still is, considerably greater than the total estimated mass of all the galaxies in such clusters, dark matter halos included. However, the estimated total mass of such clusters exceeded (and still exceeds) that of the IGM by a factor of ~5.
Along the way,
and completely independently, cosmological research was converging on an estimate of the average mass density of the universe being ~one-fifth of the critical density; of this mass, several lines of independent evidence strongly suggested that only ~one-fifth was baryonic.
(the actual history is much, much, much more intricate than I have outlined above).
So, to cut to the chase: non-baryonic cold dark matter ("CDM"), as a theory, is extraordinarily successful ... it accounts for millions of independent observations, across the full range of the electromagnetic spectrum, and of an extraordinary range of objects (from dwarf galaxies to normal galaxies to giant galaxies to galaxy groups to galaxy clusters to the universe as a whole). In the multi-decade history of the study of CDM (to be anachronistic for several decades), there have been several 'crises', many curiosities and anomalies, a great deal of refinement and revision, hundreds and hundreds of predictions and post-dictions, etc, etc, etc, etc.
And I haven't even introduced an independent line of research: indications from particle physics of the existence of an entire class of particles hithertofore unseen, the properties of which could well match those of CDM (should CDM be composed of particles).
I have read MM's posts on this topic (there are dozens, if not hundreds), and like si I find that his characterisation of astronomy is grotesque, and his views on 'controlled experiments' etc riddled with misconceptions, internal inconsistencies, etc.
