[sjastro]

Hello Robert,

Originally Posted by madbadgalaxyman

I still remain unconvinced about the idea that reliable information about the nature of the universe can be obtained, in the sense of "information very likely to be true", from the analysis of the microwave background which is said to be a relic of the big bang.

If you observe a pattern in the background radiation and then you come up with a model to account for it; why not come up with another model which accounts for the radiation, or another one, or another one....(and so on, and so on, till you have created a billion different models, all of them equally likely to be true)
As we know, theorists are very good at coming up with multiple models, all of which they swear are true.
Only problem is, observations usually disprove most of them.

On the contrary the patterns in the CMB were theoretical predictions. So rather the model being built up around existing observation, the model predicted structures that were later supported by observation.

A case in point is the B-mode polarization discovered in the CMB last year.
The B-mode polarization is caused by both gravitational waves and gravitational lensing hence there is indirect evidence of primordial gravitational waves even prior to the latest information.

We now have two separate tests that may point to the existence of gravitational waves.

The case for gravitational waves is falling nicely into place.
Primordial gravitational waves are a prediction of combining curved space into Quantum mechanics, primordial gravitational waves were predicted to create structures in the CMB and finally technologies were developed to put the theory to the test.

We have plenty of "cosmology fanatics" in IIS....so I would like to know if they think that the current interpretations of the microwave background are mere hypotheses which could easily be disproven when further facts come to light?!?

Newton's theory of gravity wasn't disproven because it couldn't explain Mercury's orbit, a feature that is accounted for in General Relativity. It means that Newton's theory is incomplete.
Mainstream scientific theories fall into that category, theories never become truths or facts. As technologies improve as new tests are developed or existing tests are performed at greater precision, we may find the existing theory to be more incomplete instead of being wrong.
There are no viable theoretical alternatives, plasma cosmology cannot explain the CMB structures. Many alternative explanations are so bizarre they fall into the category of pseudoscience or conspiracy theories.
For example one theory suggests the CMB is nothing more than microwave radiation emitted from the Earth's oceans. The trouble with this theory is the Earth's atmosphere is largely opaque to most microwave radiation, in fact the most common frequency in the CMB should be completely blocked off by the atmosphere!
Another theory suggests a faulty antenna design in which case the CMB is nothing more but noise. Unfortunately for this there have been two separate American and one European probe each with ever improving technologies for background detection.

Cosmologists seem to be people who adopt the manner and tone of "true believers"; why do they seem to be unable to adopt a skeptical tone in relation to their theories?

I'm sure on a personal level some cosmologists might have this attitude as would some microbiologists, particles physicists, palaeontologists or from any scientific discipline.
I doubt however its an exclusive province amongst cosmologists.

Regards

Steven