Is determinism truly at play in this scenario?

[eloheim]

Consider the following thought experiment: Alice and Bob live in a universe that is perfectly described by a deterministic theory. Alice is in her spaceship deep in intergalactic space. Bob (on the outside) measures the state of Alice's ship and everything inside of it. He then uses the theory to compute that Alice's ship is going to explode. He sends a message to inform Alice, and she then pushes the emergency shutdown button, so that the ship doesn't explode. This scenario doesn't contradict determinism, because Bob's calculation only told him what was going to happen if Alice never receives the message.

So howcome Bob didn't just calculate Alice's brain states as well, and use simulations to ensure that his message would be interpreted properly and begin the correct cascade of events leading from Alice's brain correctly deciphering the note to initiating the necessary motor movements for push the off button, to the ship responding properly and the explosion being averted?

I may have more to say about your post later because I think there's some interesting fodder in there...something almost makes me think of the halting problem incarnate...

 

[stevendaryl]

So howcome Bob didn't just calculate Alice's brain states as well, and use simulations to ensure that his message would be interpreted properly and begin the correct cascade of events leading from Alice's brain correctly deciphering the note to initiating the necessary motor movements for push the off button, to the ship responding properly and the explosion being averted?

I may have more to say about your post later because I think there's some interesting fodder in there...something almost makes me think of the halting problem incarnate...

I think the halting problem is exactly relevant. What the halting problem proves is that even when everything is perfectly deterministic, it may be impossible to make precise predictions in certain circumstances. You can actually force such a situation to occur by attempting to create a paradox.

 

[eloheim]

Different course (from my previous post) for a second. I hope I'm not missing something major here as far as how 'superdeterminism' goes, ...but can someone explain to me how exactly systems with no shared history or interaction could 'know' how to conspire together to produce the kind of correlations we see in entanglement games, etc.? Mustn't there be some physical mechanism or explanation?

I read the 'bell loophole' argument as being for a way to account for bell stats--while keeping the EPR premises (partially?) intakt--or no? Or does 'superdeterminism' imply each particle has access to any/all information about other happenings in the universe, regardless of distance or time? Because I don't see how else or why causality and appearances would be kept up so carefully in a universe as complex as ours.

 

[Fredrik]

So howcome Bob didn't just calculate Alice's brain states as well, and use simulations to ensure that his message would be interpreted properly and begin the correct cascade of events leading from Alice's brain correctly deciphering the note to initiating the necessary motor movements for push the off button, to the ship responding properly and the explosion being averted?

I was talking about measuring "the state of Alice's ship and everything inside of it", so this includes her brain state. Bob then calculates what the ship and everything inside it will do for the next five minutes or so. I'm assuming that he knows exactly how every possible message he can send will change the state of the ship and everything inside it, so that he can use the changed state as the starting point of a new calculation. Since we're talking about a deterministic theory, there's exactly one solution to the equations of motion (one thing that Alice and the ship can do) for each message that Bob can send. But there's no reason to think that any of them describes a future where the message is received and understood, but still ignored.

If there is such a solution, then yes, the universe that Alice and Bob live in is such that Bob can make Alice behave in a self-destructive way by doing something that we would think is completely unrelated to what she ends up doing. It could be something as silly as including a specific code in the message that Alice doesn't even see is there. It would be appropriate to call such a code "a spell" and the result "magic". As long as there's no evidence of anything like that in our universe, I'm not going to spend too much time worrying about its possible existence.

The point of my argument is that weird behavior ("magic") isn't a result of determinism. If there is such a thing in a deterministic universe, it's a consequence of the existence of "magical" solutions to the equations of motion, not a consequence of the fact that the theory is deterministic.

 

[craigi]

I was talking about measuring "the state of Alice's ship and everything inside of it", so this includes her brain state. Bob then calculates what the ship and everything inside it will do for the next five minutes or so. I'm assuming that he knows exactly how every possible message he can send will change the state of the ship and everything inside it, so that he can use the changed state as the starting point of a new calculation. Since we're talking about a deterministic theory, there's exactly one solution to the equations of motion (one thing that Alice and the ship can do) for each message that Bob can send. But there's no reason to think that any of them describes a future where the message is received and understood, but still ignored.

If there is such a solution, then yes, the universe that Alice and Bob live in is such that Bob can make Alice behave in a self-destructive way by doing something that we would think is completely unrelated to what she ends up doing. It could be something as silly as including a specific code in the message that Alice doesn't even see is there. It would be appropriate to call such a code "a spell" and the result "magic". As long as there's no evidence of anything like that in our universe, I'm not going to spend too much time worrying about its possible existence.

The point of my argument is that weird behavior ("magic") isn't a result of determinism. If there is such a thing in a deterministic universe, it's a consequence of the existence of "magical" solutions to the equations of motion, not a consequence of the fact that the theory is deterministic.

A deterministic system behaves deterministically in isolation. If a system can be modifed by an external indeterministic system then it is not intrinsically determinisitic, though it may behave deterministically until modified.

A deterministic system can be separated into deterministic subsystems. If the entire universe were to be deterministic, then in your example, neither Alice or Bob could change their predestined decisions. It would appear to both Alice and Bob that they were making decsions based upon the information they had, but those decisions and that information would be predetermined.