Compatibility of MWI with probability of outcomes

[Minnesota Joe]

Determinism can involve retrocausality I think. Or rather, correlation, as a combination of causality and retrocausality.

In the Many Worlds Interpretation? In any case, wouldn't it still be determinism? So the outcomes necessarily follow from the initial conditions. I'm sorry, maybe I don't understand what you are driving at.

 

[entropy1]

In the Many Worlds Interpretation? In any case, wouldn't it still be determinism? So the outcomes necessarily follow from the initial conditions. I'm sorry, maybe I don't understand what you are driving at.

Ok, let me be clearer: IF A -> B, or: "IF A THEN B", then you could say A and B are causally linked. But they are also retrocausally linked, because the equivalent assertion is: NOT-B -> NOT-A, or: "IF NOT B THEN NOT A". The rule is deterministic, but the values are left to fill in. If you fill in A, B follows, but if you fill in (NOT-)B, (NOT-)A follows. The question remains: who determines what?

 

[Minnesota Joe]

Ok, let me be clearer: IF A -> B, or: "IF A THEN B", then you could say A and B are causally linked. But they are also retrocausally linked, because the equivalent assertion is: NOT-B -> NOT-A, or: "IF NOT B THEN NOT A". The rule is deterministic, but the values are left to fill in. If you fill in A, B follows, but if you fill in (NOT-)B, (NOT-)A follows. The question remains: who determines what?

I'm still not sure what you mean. "If A then B, A, therefore B" concludes something quite different than, "If not-B then not-A, not-B, therefore not-A". They contradict each other on the common reading, since it is not possible that (A & not-A). They can't both be true. If, instead, you are referring to conditions on the wavefunction being specified at $t_1$ compared to some later $t_2$, then they have to be consistent with each other. You should be able to derive the first conditions from the second conditions and visa versa, just using the Schrödinger equation.

 

[entropy1]

If, instead, you are referring to conditions on the wavefunction being specified at $t_1$ compared to some later $t_2$, then they have to be consistent with each other. You should be able to derive the first conditions from the second conditions and visa versa, just using the Schrödinger equation.

Then I think you are talking about A <-> B, or (A -> B) AND (B -> A), which is equivalent to NOT-A <-> NOT B. I distinguish the rule and the values. You may think of fixed rules, but who fills in which values? I think that in the deterministic view of QM, MWI, this is solved by yielding all possible outcomes (all possible values). But I have to say I am not a physicist.

 

[Minnesota Joe]

Then I think you are talking about A <-> B, or (A -> B) AND (B -> A), which is equivalent to NOT-A <-> NOT B. I distinguish the rule and the values. You may think of fixed rules, but who fills in which values?

Who or (I'm more inclined to say) what sets the initial conditions for the universal wavefuction is irrelevant to the point. After they are set, everything is determined by the Schrödinger equation. That includes our actions and observations. I'm talking about MWI in particular of course. Something analogous would follow for other deterministic theories of QM, but the equations would be different. Do you disagree with what I've written?

 

[PeterDonis]

COULD you say that the outcome is not determined until observed, and NOT EVEN determined AFTER that because we have the superposition of ALL outcomes?

No. MWI is always deterministic.

The correct way to say it is the way I have already said it.

To be speculative

Personal speculations are out of bounds.

 

[PeterDonis]

The OP question has been answered and the thread is becoming speculative. Thread closed.