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Topic: virus: very short question (Read 930 times) |
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hell-kite
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virus: very short question
« on: 2004-11-30 05:54:43 » |
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The whole Planck/Heisenberg/Einstein thing - implying by the formulation that I know not the least bit of it -, does it really speak against determinism or merely against predictability? Does it really speak for the (ontological) reality of chance, or for (more or less epistomologically) accepting a "chance" factor because we will never be able to trace speed AND position simultaneously?
Can anyone give a concise answer to this?
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Othello. Thou dost conspire against thy friend, Iago, If thou but think'st him wrong'd, and mak'st his ear A stranger to thy thoughts.
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Rhysenn
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Re:virus: very short question
« Reply #1 on: 2004-12-04 21:46:38 » |
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I hope someone provides an answer to this eventually because it is a question i have often wondered about myself.
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rhinoceros
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My point is ...
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Re:virus: very short question
« Reply #2 on: 2004-12-05 14:08:35 » |
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[hell-kite] The whole Planck/Heisenberg/Einstein thing - implying by the formulation that I know not the least bit of it -, does it really speak against determinism or merely against predictability? Does it really speak for the (ontological) reality of chance, or for (more or less epistomologically) accepting a "chance" factor because we will never be able to trace speed AND position simultaneously?
Can anyone give a concise answer to this?
[rhinoceros] I have been meaning to write a reply to this but never found the time to sort out references and points of view. I am not sure a concise answer can be given, especially when "ontologies" are involved, but I can make a few points for now.
The usual definitions of determinism are based on descriptions using macroscopic empirical quantities such as position (where is the particle) and momentum (which way is it going and how). This is essencial for knowing a situation and being able (in principle) to make predictions from it, which is the whole point of determinism.
This kind of determinism is untenable in the quantum world, even in principle. It is *not* that the quantum particle has a position and a momentum which we can't measure... It just doesn't have them.
When we try to make a prediction that we can understand, we force a particle into a situation in which we can measure a position and then... there is no "how it is moving" -- no prediction. Or, we force it into a situation in which we can measure how it moves and then... there is no "where it is".
There have been big efforts by "quantum realists" to discover "hidden variables" which determine the behavior of a quantum particle. If that was true, we would be able to say that a particle's position and momentum is always there but we can't measure them both at once for practical reasons. All these efforts have not only failed, but also proven wrong by crucial experiments.
The only "realist" view which has survived is David Bohm's, I think. But he had to cheat: To save the concept of determinism in the quantum world he gave up on the familiar macroscopic quantities such as position and momentum and assigned an ontological reality to a "pilot wave" (deBroglie's idea) which accompanies a particle, and is represented by the wave function. In other words, the probability wave is deterministic. Small consolation if it can't give us a position and a momentum... but at least it can give us predictions in its own terms.
A note about position, momentum, energy, time and all these familiar concepts: We often take them as given, almost "Platonic", entities. It helps sometimes to ponder where they came from. The concept of position or length, for one, came from our observation that if we place a ruler along something it fits a number of times, the same number of times always. One can imagine a world of eternal flow and shape-shifting where this would not be possible.
Now, an interesting part is the relationship between the quantum world and the world of our experience. As Niels Bohr noticed right from the beginning (this is not a straight quote) (a) the questions we pose to the quantum world are necessarily based on concepts from our own world and (b) whatever we find out about the quantum world must be such that it produces what we observe in our own world.
So, something which has always amazed me is that the determinism which we observe (or just assume?) in our own world is consistently produced by probability waves, according to the point (b) above.
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hell-kite
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Re: virus: very short question
« Reply #3 on: 2004-12-05 17:29:41 » |
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Thanks a lot for your answer, rhino! Interesting & illuminating (yet not fully satisfying, see below). Sadly, I don't have any time right now for a thoughtful reply NOR for entering the prisoner's dilemma discussion - at least not until the middle of the week...
So far only this,
[rhino] This is essencial for knowing a situation and being able (in principle) to make predictions from it, which is the whole point of determinism.
[hell-kite] Well, is it? It might be, but my understanding is that determinism simply is the notion that what happens is determined, regardless of whether we can consider all variables or make predictions or trace momentum and position simultaneously or whatever. That's why I called it "ontological", I guess.
Ah well. Sorry - listening but never speaking, Björn
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Othello. Thou dost conspire against thy friend, Iago, If thou but think'st him wrong'd, and mak'st his ear A stranger to thy thoughts.
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