The latest cosmological discovery at the south pole by the Bicep2 collaboration has been in the news over the last few days impacts on this discussion..."Detection of B-mode Polarization at Degree Angular Scales" - i.e. the spectacular new structure identified in regards to the rotation of the polarization angle of cosmic microwave background radiation.
Primordial gravitational wave discovery heralds 'whole new era' in physics
BICEP2: Primordial Gravitational Waves!
BICEP2 2014 Results Release
As this has been raised here, it would indeed be interesting to know more about the size and nature of the magnetic fields in the early universe that would needed to fully or partially account for the observed B-mode Polarization patterns (Faraday Effect) and perhaps any other potentially plausible explanations as well.
The Bicep2 team confidently ascribe the striking patterns in the B-mode Polarization to gravitational waves at a very early phase of a big bang inflationary expansion. I would like to know if there some physical reason for definitively ruling out magnetic fields affecting light polarization, much later on in the development of the universe?
If the BICEP2 teams measurement results holds up to later scrutiny they are definitely worthy of a Nobel Prize in their own right (independent of the theorical model to explain the results). Given the very speculative nature of cosmology my preference would be for the measurement team to be much more guarded in regards to theoretical interpretation at this stage, letting the theorists fight over the detailed interpretation as a separate exercise and in separate papers.
Without a little forced separation between theorists and experimentalists, the danger is that experimental researchers only end up seeing what they expect to see according to a single dominent theoretical paradigm, and discount measurement anomalies that don't quite fit their theory laden expectations.
My personal view is that the public pay more than enough money into the science to allow more than one scientific theoretical school of thought to co-exist simultaneously, especially so in a subject so speculative as cosmology. If strong churning convective mass flows and magnetic fields in the early universe cannot be ruled out as a possible theoretical explanation for these results then how can we really definitively know that the BICEP2 team have detected gravitational waves existing in their model of a very early inflationary universe?