[Bill S (OP)]

...it is entirely possible for people (not you) to have zero knowledge...

I appreciate the "not you", but there are times when I would be inclined to argue with it. 

Having not read a book since I was in Hosp in Nov 2016, I'm trying to restructure my routine to do something about that.  I'm about to have a go at Adam Becker's "what is Real".  Does anyone know if it's worth the effort?

[Bill S (OP)]

I’ve had a quick look at this and think it is relevant to this thread. 

https://www.quantamagazine.org/pilot-wave-theory-gains-experimental-support-20160516/

I understand that Bohm may, at some point, have said that the pilot wave idea might not work.  I have long suspected that this may have had more to do with political and other pressures than to his own doubts.  This article suggests that he kept working on it until his death.

[alancalverd]

Another important point, that has been mentioned in this thread, but not explicitly focused on is this: Nothing can ever be known exactly--there is always some uncertainty.

It is absolutely crucial to distinguish between uncertainty - the confidence limits of a measurement - and indeterminacy - the fact that ΔpΔx ≥ h.

We can measure the density or x-ray diffraction pattern of solid hydrogen and thus deduce the effective diameter d_H of a hydrogen atom with an uncertainty of, perhaps, ± 0.1% But the fact that  d_H >> d_proton is due to the indeterminacy of the electron.