Yes, EPR does not suggest non-locality as FTL signalling. I was saying the correlational non-locality requires first accepting the absolute (a view from nowhere) objectivity. I.E. it is meaningful to think about Alice’s measurement and how it correlates with the space-like separated Bob’s measurement. This reasoning is directly examining the perspective-independent reality. If we reject Step 3, therefore making perspectives fundamental then this correlational non-locality could not exist. For example, from Alice’s perspective, Bob’s measurement can only affect actions upon her when its light cone reaches her, which would definitely happen within the light cone of her own measurement, making any correlation local. I’m under the impression that QBism argues against quantum non-locality with similar logic.
What correlates are two sets of measurements. It’s a statistical property .
Alice can note that Bobs observations are correlated with hers , and vice versa—neither needs a view from nowhere.
If not employing a “view from nowhere” then the non-locality has to be formulated with a perspective switch. E.g. Alice considers her own measurement then imagine Bob’s measurement from his perspective (as opposes to find out Bob’s measurement when it affects actions upon her). This non-locality does not apply to any perspective.
Another way to look at it: QM is local. But the conceptual perspective switch is instantaneous/FTL. Thus the non-local statistics.
They can write their result on two pieces of paper and bring them together. But as long as we treat perspective as fundamental, there still won’t be any non-locality. Because the spins are perceived by actions upon a perspective center. And those actions cannot be spacelike separated. For example, if the two pieces of paper are sent to me, from my perspective all I can say is something like “since I got Alice’s result as spin up, safe to say I will get Bob’s result as spin down.” Non-local correlations like “Alice measured up, so Bob will measure down” is either a perspective switch between the two or a view from nowhere statement.
I agree that measurements are objective once made (in the sense of perspective-invariant not perspective-independent). But Alice and Bob are not analyzing the same set of measurements. Each of them from their respective perspective analyzes actions upon him/herself. Their deduction about the spins would have opposite causal arrows. But as long as we don’t switch perspectives, things would be local.
They can write their result on two pieces of paper and bring them together. But as long as we treat perspective as fundamental, there still won’t be any non-locality.
Nonocality is more than one thing. The correlation I spoke of continue to exist even if your metaphysics say they can’t.
That’s fair. I think it would be beyond my expertise to criticize other notions of correlational non-locality. I just wanted to point once treating perspectives as fundamental, the non-locality cannot be formulated in QM. Somewhat similar to QBism’s treatment of nonlocality.
Yes, EPR does not suggest non-locality as FTL signalling. I was saying the correlational non-locality requires first accepting the absolute (a view from nowhere) objectivity. I.E. it is meaningful to think about Alice’s measurement and how it correlates with the space-like separated Bob’s measurement. This reasoning is directly examining the perspective-independent reality. If we reject Step 3, therefore making perspectives fundamental then this correlational non-locality could not exist. For example, from Alice’s perspective, Bob’s measurement can only affect actions upon her when its light cone reaches her, which would definitely happen within the light cone of her own measurement, making any correlation local. I’m under the impression that QBism argues against quantum non-locality with similar logic.
What correlates are two sets of measurements. It’s a statistical property . Alice can note that Bobs observations are correlated with hers , and vice versa—neither needs a view from nowhere.
If not employing a “view from nowhere” then the non-locality has to be formulated with a perspective switch. E.g. Alice considers her own measurement then imagine Bob’s measurement from his perspective (as opposes to find out Bob’s measurement when it affects actions upon her). This non-locality does not apply to any perspective.
Another way to look at it: QM is local. But the conceptual perspective switch is instantaneous/FTL. Thus the non-local statistics.
No. They just need to write down their observations on two strips of paper, and bring them together .
Its an important feature of QM that measurements are pretty much objective and classical once you have made them.
They can write their result on two pieces of paper and bring them together. But as long as we treat perspective as fundamental, there still won’t be any non-locality. Because the spins are perceived by actions upon a perspective center. And those actions cannot be spacelike separated. For example, if the two pieces of paper are sent to me, from my perspective all I can say is something like “since I got Alice’s result as spin up, safe to say I will get Bob’s result as spin down.” Non-local correlations like “Alice measured up, so Bob will measure down” is either a perspective switch between the two or a view from nowhere statement.
I agree that measurements are objective once made (in the sense of perspective-invariant not perspective-independent). But Alice and Bob are not analyzing the same set of measurements. Each of them from their respective perspective analyzes actions upon him/herself. Their deduction about the spins would have opposite causal arrows. But as long as we don’t switch perspectives, things would be local.
Nonocality is more than one thing. The correlation I spoke of continue to exist even if your metaphysics say they can’t.
That’s fair. I think it would be beyond my expertise to criticize other notions of correlational non-locality. I just wanted to point once treating perspectives as fundamental, the non-locality cannot be formulated in QM. Somewhat similar to QBism’s treatment of nonlocality.