Popper defined a physical proposition to be one which can at least in theory be denied by observation. The physical propositions I presented in Savior Imperative are 3 things: special relativity indicates a block universe; the experienced present corresponds to a real aspect of information processing in brains, and experienced valence corresponds to a real aspect of information processing in brains.
I claim that it is a physical proposition by Popper’s definition because any of these things can be denied by observation. Special relativity’s indication of a block universe can be denied by one of many observations including observing a failed time dilation attempt. The proposition that the experienced present corresponds to a brain process can be denied by one of many observations including finding another medium through which the present is experienced. The proposition that experienced valence corresponds to a brain process can be denied by one of many observations including observing valence in the absence of processes assumed to be fundamental to its generation.
A property A is said to supervene on a property B if any change in A necessarily implies a change in B. The property of block-time supervenes on our observed time dilation. If special relativity were any different, we would see different effects. Hence, the property of block-time is not some extra addition to the physical nature revealed with the lens of special relativity; it is necessarily implied.
Since any change in [block-time + the other more uncontroversial aspects of special relativity] must consist of a change in at least one component property, we see that the combination does indeed supervene on the individual properties.
The point of noting this is that in making this physicalist claim, I am supposing the existence of what may be called an abstract concept – if we define as abstract, that which we cannot taste or touch or see. You do not possess the eye’s of a mythological being such as a great Buddha or a Christian God, therefore you cannot see the eternal block-time. Yet this proposition of block-time, which might seem an abstraction to the ordinary human mind, is physical – because if it were changed, then readily observable things would change. If the hyper-surface of the present couldn’t include future beings in Andromeda as the observer moves through spacetime, then this would constitute a modification to special relativity. We would then reasonably expect that its observable predictions such as time-dilation wouldn’t have borne out.