I'm not going on about quantum theory, I merely state that if anything questions the fundamentals of the principia that is it, not general relativity. The beauty of general relativity is that it can apply in the quantum place as well as the observable universe to a degree, mass calculations can't.

I don't wish to start a tedious argument about this but your remark that general relativity supercedes the principia requires challenge. They relate, not differ. The absolutism was removed by Einstein but not the fundamental relationship, which was relativity anyway. ...

Regarding ether and dark matter. Good point but ether was just a convenient way of wondering how anything can propagate in a vacuum. Dark matter raises the question sgain, but not as a convenient hypothesis for vacuum propagation as I see it. Although it isn't and never was my field. My earlier professional interest in force and mass no longer exist since selling up 10 years ago for that matter. I remain fascinated but leave the advances to others.   Enough on with beer, pickled eggs and The NHS...