Last Thursday I attended one day of the UK-Germany National Astronomy Meeting in Manchester and I gave a talk in the (unofficial) Cosmology 4 'Dark Energy, Dark Matter and Modified Gravity' session on my recent work 'Testing quantised inertia with wide binaries'. I was asked a few interesting questions. Someone asked me whether I'd applied MiHsC/QI to the Cosmic Microwave Background (CMB). I have done some work on this: I can model the apparent supression of power at the largest scales using the Hubble-scale Casimir effect, but haven't taken account of curved space yet, and further: that CMB anomaly does not poke outside the error bars yet.
One chap suggested that I could look at photons since they traverse areas of low acceleration. OK, but looking for a more direct test, I am now trying to focus on either very simple astronomical tests (wide binaries) or terrestrial experiments (lab tests). He also said that I should not cite the Pioneer anomaly as a successful test any more because Turyshev et al. have modelled the Pioneer anomaly as a mundane thermal radiative reaction force: heat emitted from the RTGs bounces off and pushes the craft. However, although I haven't yet read their paper in detail, it seems they have used a complex reflection model with many adjustable parameters (tricky) and also I would have expected there to be a significant decay in the Pioneer anomaly if radiation was the cause since the RTGs should have significantly cooled over the 30 years of data, but Anderson et al. saw no decay in the anomaly. Turyshev et al. claim there is a decay. I need to look at the data to decide this.
Anyway, someone then asked 'Can you tell me anything that would convince me that inertia is caused by Unruh radiation'. That nonplussed me because I'd just presented all my comparisons of MiHsC/QI with the data and the agreement with data is what convinces me. Anyway, I answered: 'My main reason is that it works'. By this I mean that if you do assume that inertia comes from Unruh radiation, and the Hubble-scale Casimir effect which follows, then you get successful experimental predictions that are unobtainable from other theories. I do not yet have a specific physical model for exactly how the Unruh radiation might interact with objects and cause inertia (I think this is what this person wanted, but for me that has to come later, and slowly). I have a few ideas about possible mechanisms, but no experiments to discriminate between them yet.