Is causality challenged by quantum theory's reliance on indeterminacy?

[DrChinese]

1. That assumes that you can ever set up two identical scenario, just because you are dealing with the same kind of particle or event. I don't assume this. To the contrary, you can never set up the same scenario, because scenario will always be separated either in time or space.

2. I don't know. Are you saying that the copenhagen interpretation denies non-locality? As far as I know, phenomena such as quantum entanglement are rather widely held.

In any case, we don't need nonlocality for causality if we discount our basic ability to replicate the same scenario (and therefore make valid causal predictions). In that case, all we need to stop assuming is determinacy.

3. As far as I've discerned, there will always be different energy balances in different quantum particles and events, and in the quantum vacuum. It surprises me no one has considered the vacuum.

We already have good reasons to assume it isn't empty, with the discovery of things such as dark energy, dark matter, gravitational fields, and other entities we aren't aware about. So how could we say that particles erupt spontaneously from the vacuum "without any cause" and receiving their energy from "nowhere", or particles decay for "no reason", when clearly the vacuum is filled with energy and disturbing forces which could causally explain this without our determinacy?

1. You must admit this is circular reasoning. You assume causality because all events are unique...?

2. You can't have local causality, per Bell.

3. Isn't that just moving the goal posts? You are again coming back to the idea that causality may be correct, once we find the "missing" cause. I already believe that as a possibility.

 

[Borean]

1. You must admit this is circular reasoning. You assume causality because all events are unique...?

No, not at all.

I am only saying that I reject the premise that you can succesfully replicate "two identical scenario".

That premise would be a requirement before you could expect two scenario to be fully "causally" identical, or indeed to conclude acausality if the scenario were not, seemingly, "causally" identical.

By rejecting the premise, I neither have to expect that two scenario are causally identical (given causality), or conclude acausality when I find that they are not causally identical.

2. You can't have local causality, per Bell.

What I said already presumes that claim.

3. Isn't that just moving the goal posts? You are again coming back to the idea that causality may be correct, once we find the "missing" cause. I already believe that as a possibility.

No, that is just elaborating on the reasons _WHY_ there can never be two causally identical scenario (and therefore the premise of Bells experiment is faulty).

 

[DrChinese]

No, that is just elaborating on the reasons _WHY_ there can never be two causally identical scenario (and therefore the premise of Bells experiment is faulty).

Well, you are now entering the world of the philosophical (not a bad thing, and I happen to like this particular area). But science is about explaining patterns and pattern exceptions. Useful theories find commonality in events that are similar in specific ways, even if not identical.

Further, I quite agree that causality may not hold because no 2 events are identical. (Since by all logic, you could require the complete state of the universe to figure into any outcome.) But that does not change the fact that physics is full of USEFUL theories in which our knowledge is relatively minimal regarding the initial state.

More relevantly, it changes Bell's conclusion not at all. It simply means that no physical theory can be proposed which is local realistic. Because there can be no pattern matches for such a theory during experiments as strong as those for QM. (I.e. the cos^2 rule for entangled photons.)

 

[Borean]

Well, you are now entering the world of the philosophical (not a bad thing, and I happen to like this particular area). But science is about explaining patterns and pattern exceptions. Useful theories find commonality in events that are similar in specific ways, even if not identical.

It's not actually a "philosophical" invention of mine.

It's a premise for Bell's findings to hold true.

 

[DrChinese]

It's not actually a "philosophical" invention of mine.

It's a premise for Bell's findings to hold true.

I disagree here. The question is whether a local realistic theory can produce the statistical predictions of QM. Bell says it cannot. Causality is not an assumption per se.

 

[Borean]

I disagree here. The question is whether a local realistic theory can produce the statistical predictions of QM. Bell says it cannot. Causality is not an assumption per se.

Thats not what I meant.

I will quote what I already said (to your post actually):

DrChinese:
Well, it would be a good hint (in favor of causality) if you could set up the same scenario and get the same result every time.

Borean:
That assumes that you can ever set up two identical scenario, just because you are dealing with the same kind of particle or event. I don't assume this. To the contrary, you can never set up the same scenario, because scenario will always be separated either in time or space.

 

[DrChinese]

Thats not what I meant.

I will quote what I already said (to your post actually):

DrChinese:
Well, it would be a good hint (in favor of causality) if you could set up the same scenario and get the same result every time.

Borean:
That assumes that you can ever set up two identical scenario, just because you are dealing with the same kind of particle or event. I don't assume this. To the contrary, you can never set up the same scenario, because scenario will always be separated either in time or space.

Probably a case of nested quoting, because I don't have much problem with this. And reviewing your earlier comment further, I agree with your idea that vacuum fluctuations could be a source of indeterminacy.