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Originally Posted by modest
And your particular objection is called the andromeda paradox:
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Didn't mean to object the validity of relativity at all, if that's the implication you got.
btw, rather interesting that the "Rietdijk-Putnam-Penrose argument" refers to something that surfaced as late as in the sixties. That implication regarding "present moment" should be abundantly obvious immediately from the premise of relativity. I'm sure many people have made comments about it, including Einstein.
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Rietdijk-Putnam argument - Wikipedia, the free encyclopedia
which is only a paradox (like so many things in SR) if you assume a person can receive information faster than light or assume people can know things which are impossible to know. In other words, only by making bad assumptions is the relative plane of simultaneity a problem rather than always perfectly consistent with observation.
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Yes, in other words the simultaneity planes themselves are not observable at all; they are things we have defined as part of relativistic spacetime, but their ontological reality is an assumption.
Following that, when people think about the implications of relative simultaneity, many end up assuming there is then no specific "present moment" existing at all; that it's not fair to say whether Andromedian invaders are underway or not, but rather future and past exists "all the time". That obviously leads to rather specific assumptions to explain our subjective experience, where things still seem to be "moving".
Well, if that's now clarified, one should pay attention to the possibility of modeling reality with absolute simultaneity, or technically with just about any sort of simultaneity. By defining simultaneity as it's defined in relativity, it makes certain aspects of
our description of nature very simple. Yet, it being valid does not constraint the reality itself into a static spacetime block in any ontological sense. It is poor judgment when people think relativity = static spacetime.
That is not to condone the ontology of absolute simultaneity as much as it is to point out that spacetime is also part and parcel of our conception of reality; A matter of defining (many) things that way. Referring to DD's analysis, it is rather interesting that it seems it is the symmetries in our "definitions of entities" that make relativistic descriptions valid.
Ps. Note that the Wikipedia page listed as one of the references
"A Rigorous Proof of Determinism Derived from the Special Theory of Relativity".Well, that is simply not valid. Someone is seeing that as "proof" because they take some assumptions in their worldview as ontologically valid, on pure faith.
-Anssi
