Posted: Oct 07, 2011 3:08 pm
by Teuton
twistor59 wrote:
Teuton wrote:But physical reality cannot be reduced to mere possibilities or probabilities. The real properties of spacetime points or regions must be actual determinate properties.

Emphasis mine. But that is the very heart and soul of quantum theory. A system might or might not possess a definite value of such a quantity until a measurement is made. In the cases were it does not possess a definite value, quantum theory is not making definite predictions about individual systems, but rather about ensembles of systems.

Physical reality is physical actuality and not a "semireal" limbo or twilight zone of mere possibilities, potentialities, or probabilities. Physical objects or systems must have some physical properties, since nothing can exist propertylessly; and I don't know what it means to say that they don't have definite, determinate properties unless physicists have measured them, i.e. that unmeasured physical reality swims in a sea of indeterminacy or vagueness. I doubt that there are and can be indeterminacies and vaguenesses in the world that are ontological rather than semantic. That is, I doubt that vague predicates or concepts represent real properties that are vague themselves.
(For example, is it even coherent to say that an object has a mass but none of the possible determinate properties belonging to that determinable property, e.g. a mass of exactly 3kg?)

twistor59 wrote:It depends on the point of view you take - maybe the spacetime point itself is an abstraction ....

Actually, I do think that spacetime points and point particles are mathematical abstractions or idealizations. (But I believe in the physical reality of non-zero-dimensional spacetime regions and particles.)