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AquinasD
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PostPosted: Thu Oct 27, 2011 10:48 pm  The Metaphysical Possibility of Randomness Reply with quote

Before I begin our analysis of the concept of “randomness” and its metaphysical possibility, we must first come to terms with what ‘randomness’ means.

When the term “random” is used to describe some event, this is in opposition to its being determined or even explainable in terms of what came before it. So randomness would cover any event for which the antecedent is allowed to have two or more consequents, where the occurrence of either over the other possible consequent is not explainable by the antecedent cause. Therefore, when we speak of “randomness” in the context of causation, we mean something like

randomness: when something occurs for no reason

Now for our question; is randomness metaphysically possible? Before I delve into the strictly metaphysical argument, I want to defuse a possible argument that comes from quantum mechanics. This argument states that randomness must be possible, for it is utilized in certain interpretations of quantum mechanics, viz. M-Theory and the Copenhagen interpretation.

However, I think what is important to note is that randomness is scientifically unfalsifiable. We must remember that science operates under a method that is of the form “If x were true then we would see y under conditions z.” Randomness is not observably distinguishable from events that occur in which we are simply unable to observe the antecedent causes of the consequent. If it is not observably distinguishable, then it is not scientifically unfalsifiable. This means that garnering support from science-qua-scientific-method in favor of the possibility of randomness is to beg the question. What is actually the case is that these interpretations of quantum mechanics are presenting a metaphysical explanation (more properly, non-explanation) for what happens, not a scientific one. This means that no substantial help will come from science in answering this question. It is a purely metaphysical exercise.

I think that randomness, defined like above (based on how it is typically used in the context of causality), is meaningless. What I mean is that the proposition “Things can happen for no reason” is void of semantic content. Let us break it down to see what it would mean, and in this way we will see that the only possible, and therefore necessarily true, proposition is that “Things happen for a reason.”

Causality is linked to being. If something were to cause another thing, then it must be the case that between objects they share an aspect in their forms that makes them capable of interacting directly with each other, and their respective forms will inform the ontology of the causation as it occurs. In other words, it is in the essence of (at least) two beings that determines how the inputs (the motion, or change, of the antecedent efficiently causal being) shall be, as it were, translated to outputs; a sort of instantaneous calculation is performed by both of the objects that yields its result.

To break this down concretely, take the event of a billiards ball striking another. We know that when one strikes the other, the other will be pushed off in the direction it is struck from. What causes just this type of event to occur, and none other, is the essences of the two billiards balls themselves, such that the first’s form informs the other of what it will do in reference to its own form (in this case, they both happen to be spherical).

Now what we must note is that, insofar as the beings involved determine what shall happen in any event, that definite beings give definite conclusions. It is the very definiteness of the beings that allows the transference of energy to occur as it does, for otherwise there must pertain an indefiniteness of just what occurs, for definition cannot follow from indefinition. But what occurs is, in fact, definite, and it must be definite, for otherwise it would not be. This is because any being that is at all a being must be a certain particular being, a definite being, for otherwise it should fail to be a being at all. But then, if there is no room for indefiniteness in a being, then we must conclude that there is no room for indefiniteness in cause.

Concretely, what we mean by this is that it cannot be a being’s final cause that it will cause A or B, and that it causes either A or B shall be for no reason. It simply wouldn’t mean anything to state that it is a thing’s nature to not be naturally disposed towards one consequent over another under certain conditions; we’d be saying it’s nature is to be without nature. But if a thing has a nature, it has a nature, and if a thing didn’t have a nature, it wouldn’t be a thing. Therefore, we must conclude that, if a being is a being, it’s efficient causes can only be of a particular and explainable sort. This precludes the metaphysical possibility of randomness, because randomness requires a being to not have a nature, which is a contradiction in terms. Thus I say “randomness” is meaningless.

*What is a nature? A nature is simply what it is in the being's being to do; or, what Aristotle calls "final cause."

That there are final causes in the world is not difficult to demonstrate. Typically, we like to describe complex processes in terms of what its constituent parts do. However, this mode of explanation falters when it comes to theoretical fundamental particles, which would have no constituent parts to explain their behavior. Yet these fundamental particles would have a definite range of behaviors, and while this behavior is informed by the effective environment of that particle, it remains the case that we can only explain the particle's normative tendency by positing that it is just the nature of the particle to do what it does, and that it has the nature to do what it does is not caused by any underlying constituent parts. In other words, final causes constitute a real aspect in nature.

A practical example of final cause is any given natural law. Take Boyle's law:

"For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional (while one doubles, the other halves)."

What is being described here is the nature, of final cause, of gaseous matter. We would say it is just the nature of gas for its pressure and volume to be inversely proportional.

Just to show I'm not being illicit in my utilization of "natures" as an aspect of beings.
Post BBCode URL - Right click and save to clipboard to use later in post Post 11: Sat Oct 29, 2011 4:49 pm
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JohnPaul wrote:
IMHO, any attempts to apply formal logic to questions such as this are ultimately nothing more than word games, dependent on a host of hidden assumptions, arbitrary definitions, semantic interpretations, and even the grammatical structure of statements. Appeals to the real world for concrete examples, such as human free will, probability theory and Quantum Mechanics, are equally futile appeals to the unknown.

Quantum Theory is not even a theory. After more than 80 years, quantum theory remains nothing more than a method of calculation which is found to provide useful results, without even a hint of explanation for why it is so. The famous "Copenhagen Interpretation" as formulated by Niels Bohr essentially says "Just do the calculations and don't ask questions!"

John

In science a theory is a framework for answering all questions in its domain by making quantitative falsifiable predictions that are borne out by experiment. Quantum is that and spectactularly successful at it. There are those - the Positivists including Bohr - who claim that is all anyone can ever do.

But this is the Philosophy forum. 'Why' is always a legitimate question here.

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Post BBCode URL - Right click and save to clipboard to use later in post Post 12: Sat Oct 29, 2011 6:03 pm
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ThatGirlAgain wrote:
JohnPaul wrote:
IMHO, any attempts to apply formal logic to questions such as this are ultimately nothing more than word games, dependent on a host of hidden assumptions, arbitrary definitions, semantic interpretations, and even the grammatical structure of statements. Appeals to the real world for concrete examples, such as human free will, probability theory and Quantum Mechanics, are equally futile appeals to the unknown.

Quantum Theory is not even a theory. After more than 80 years, quantum theory remains nothing more than a method of calculation which is found to provide useful results, without even a hint of explanation for why it is so. The famous "Copenhagen Interpretation" as formulated by Niels Bohr essentially says "Just do the calculations and don't ask questions!"

John

In science a theory is a framework for answering all questions in its domain by making quantitative falsifiable predictions that are borne out by experiment. Quantum is that and spectactularly successful at it. There are those - the Positivists including Bohr - who claim that is all anyone can ever do.

But this is the Philosophy forum. 'Why' is always a legitimate question here.


I am concerned about the well-being of Schrödinger's Cat and pleased that the "Many Worlds" interpretation of quantum mechanics provides a safe haven for it in a nearby parallel world, separated from us only by an infinitesimal distance in the direction of a 4th spatial dimension.

I know there is no experimental verification of this interpretation, but neither is there any verification of any other explanation for quantum wierdness. The popular claim that when an observer makes an observation, the "wave function" of the entire universe travels faster than light and instantly collapses to agree with his observation is a little too grandiose for my taste. It makes much more sense to me that all possibilities "really" exist simultaneously, that the observer's mind or awareness is constantly cycling or scanning through a number of nearby universes, and the result of an observation randomly locks or synchronizes his awareness to one particular world in which a particular result exists, together with any and all even very distant "entanglements" of that quantum result. The randomness is in the observer's mind, not in the external universe.

After an observation, the observer's mind or awareness would have landed in another parallel universe, probably very similar to his previous one, with only a few differences at the quantum level, but very improbably in a much more distant and very different parallel universe. The observer would not be aware of this change, since his mind would now reside in the version of him existing in that new universe, and all his memories and perceptions would now come from that new 3-D brain.

This idea would explain at least some of the quantum wierdness. Of course, it also raises many more questions. What we see as a human being is really only a section or three-dimensional "slice" of a much larger four-dimensional entity. What does a four-dimensional cat look like?

John

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Post BBCode URL - Right click and save to clipboard to use later in post Post 13: Sun Oct 30, 2011 5:57 am
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JohnPaul wrote:
ThatGirlAgain wrote:
JohnPaul wrote:
IMHO, any attempts to apply formal logic to questions such as this are ultimately nothing more than word games, dependent on a host of hidden assumptions, arbitrary definitions, semantic interpretations, and even the grammatical structure of statements. Appeals to the real world for concrete examples, such as human free will, probability theory and Quantum Mechanics, are equally futile appeals to the unknown.

Quantum Theory is not even a theory. After more than 80 years, quantum theory remains nothing more than a method of calculation which is found to provide useful results, without even a hint of explanation for why it is so. The famous "Copenhagen Interpretation" as formulated by Niels Bohr essentially says "Just do the calculations and don't ask questions!"

John

In science a theory is a framework for answering all questions in its domain by making quantitative falsifiable predictions that are borne out by experiment. Quantum is that and spectactularly successful at it. There are those - the Positivists including Bohr - who claim that is all anyone can ever do.

But this is the Philosophy forum. 'Why' is always a legitimate question here.


I am concerned about the well-being of Schrödinger's Cat and pleased that the "Many Worlds" interpretation of quantum mechanics provides a safe haven for it in a nearby parallel world, separated from us only by an infinitesimal distance in the direction of a 4th spatial dimension.

I know there is no experimental verification of this interpretation, but neither is there any verification of any other explanation for quantum weirdness. The popular claim that when an observer makes an observation, the "wave function" of the entire universe travels faster than light and instantly collapses to agree with his observation is a little too grandiose for my taste. It makes much more sense to me that all possibilities "really" exist simultaneously, that the observer's mind or awareness is constantly cycling or scanning through a number of nearby universes, and the result of an observation randomly locks or synchronizes his awareness to one particular world in which a particular result exists, together with any and all even very distant "entanglements" of that quantum result. The randomness is in the observer's mind, not in the external universe.

After an observation, the observer's mind or awareness would have landed in another parallel universe, probably very similar to his previous one, with only a few differences at the quantum level, but very improbably in a much more distant and very different parallel universe. The observer would not be aware of this change, since his mind would now reside in the version of him existing in that new universe, and all his memories and perceptions would now come from that new 3-D brain.

This idea would explain at least some of the quantum weirdness. Of course, it also raises many more questions. What we see as a human being is really only a section or three-dimensional "slice" of a much larger four-dimensional entity. What does a four-dimensional cat look like?

John

Or that cat might be definitively saved or killed as the case may be by a spontaneous decoherence effect that may be natural to large systems without a conscious observer. I am a big fan of the multiverse on philosophical grounds but my version requires fairly strong isolation.

Quote:
Interference phenomena are a well-known and crucial feature of quantum mechanics, the two-slit experiment providing a standard example. There are situations, however, in which interference effects are (artificially or spontaneously) suppressed. We shall need to make precise what this means, but the theory of decoherence is the study of (spontaneous) interactions between a system and its environment that lead to such suppression of interference.
http://plato.stanford.edu/entries/qm-decoherence/

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Post BBCode URL - Right click and save to clipboard to use later in post Post 14: Sun Oct 30, 2011 3:11 pm
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ThatGirlAgain wrote:
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Or that cat might be definitively saved or killed as the case may be by a spontaneous decoherence effect that may be natural to large systems without a conscious observer. I am a big fan of the multiverse on philosophical grounds but my version requires fairly strong isolation.


I prefer to believe that the cat is neither alive nor dead, but that all possible versions of it continue to "really" exist, some of them alive and some dead, distributed in accordance with the probabilities derived from quantum theory, each in its own separate 3-D universe but all still part of a larger four-dimensional reality.

From what little I understand about the modern idea of "decoherence," it seems to be a pathetic attempt to save the idea of a collapsing wave function while avoiding the need for a conscious observer. I am a little suspicious of theories that use words like "spontaneous" and "may be." When Everett's "Many Worlds" interpretation of quantum physics came out in 1957, I was fascinated. It seemed to offer the possibility of actually explaining something.

I first became interested in physics and cosmology back in ancient times when I was in high school and read some of the books of Eddington, Jeans, and Gamow. Things were much clearer back then. Now we have been floundering around in String Theory for more than 30 years, producing a lot of "elegant" mathematics but absolutely no coherent theory and certainly no testable predictions.

I have been reading the book, "The Trouble with Physics" by Lee Smolin. He is careful to avoid insulting any fellow theoretical physicists, but has some unkind things to say about String Theory.

John

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Post BBCode URL - Right click and save to clipboard to use later in post Post 15: Sun Oct 30, 2011 7:52 pm
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Moderate Guy wrote:
I disagree. The proposition: A causes (B or C) has semantic content.


Just because you say something has semantic content does not mean it does.

I am holding that the proposition "A causes (B or C)" is meaningless like "God could create a stone so heavy He could not lift it" or "A square circle would be like this" are meaningless. It requires some enumeration of the meaning that builds into the concepts touched upon, but an understanding of those underlying concepts yields the fact that the only possible conclusion is one of negation.

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Post BBCode URL - Right click and save to clipboard to use later in post Post 16: Mon Oct 31, 2011 5:12 am
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JohnPaul wrote:
ThatGirlAgain wrote:
Quote:
Or that cat might be definitively saved or killed as the case may be by a spontaneous decoherence effect that may be natural to large systems without a conscious observer. I am a big fan of the multiverse on philosophical grounds but my version requires fairly strong isolation.


I prefer to believe that the cat is neither alive nor dead, but that all possible versions of it continue to "really" exist, some of them alive and some dead, distributed in accordance with the probabilities derived from quantum theory, each in its own separate 3-D universe but all still part of a larger four-dimensional reality.

From what little I understand about the modern idea of "decoherence," it seems to be a pathetic attempt to save the idea of a collapsing wave function while avoiding the need for a conscious observer. I am a little suspicious of theories that use words like "spontaneous" and "may be." When Everett's "Many Worlds" interpretation of quantum physics came out in 1957, I was fascinated. It seemed to offer the possibility of actually explaining something.

I first became interested in physics and cosmology back in ancient times when I was in high school and read some of the books of Eddington, Jeans, and Gamow. Things were much clearer back then. Now we have been floundering around in String Theory for more than 30 years, producing a lot of "elegant" mathematics but absolutely no coherent theory and certainly no testable predictions.

I have been reading the book, "The Trouble with Physics" by Lee Smolin. He is careful to avoid insulting any fellow theoretical physicists, but has some unkind things to say about String Theory.

John

The 'spontaneous' aspect is simply to distinguish it from observer dependent. Interactions with other entities that cause irreversible changes is what is the alleged cause of the decoherence. Personally that sounds more reasonable than requiring a conscious and presumably human observer to establish whether the cat is dead or alive. Doesn't the cat know? And the retroactive aspect of large scale wave function collapse is puzzling as well. The cat does not die on the spot but is already dead and partly decomposed. Or the cat has been alive and drunk all the milk. A different world branch is selected retroactively depending on the kind of observation made?

In any case there is the issue that the status of the cat cannot be completely isolated from the outside world. The movement or lack thereof of the cat, even to the extent of breathing, will have immediate (subject to c) gravitational consequences for the entire universe.

I know of Smolin's distaste for an extremely abstract branch of physics, a branch with a thousand different leaves on it, that so far is totally divorced from any observation. Laughing

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Post BBCode URL - Right click and save to clipboard to use later in post Post 17: Mon Oct 31, 2011 2:29 pm
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ThatGirlAgain wrote:
Quote:
The 'spontaneous' aspect is simply to distinguish it from observer dependent. Interactions with other entities that cause irreversible changes is what is the alleged cause of the decoherence. Personally that sounds more reasonable than requiring a conscious and presumably human observer to establish whether the cat is dead or alive. Doesn't the cat know? And the retroactive aspect of large scale wave function collapse is puzzling as well. The cat does not die on the spot but is already dead and partly decomposed. Or the cat has been alive and drunk all the milk. A different world branch is selected retroactively depending on the kind of observation made?

In any case there is the issue that the status of the cat cannot be completely isolated from the outside world. The movement or lack thereof of the cat, even to the extent of breathing, will have immediate (subject to c) gravitational consequences for the entire universe.

I know of Smolin's distaste for an extremely abstract branch of physics, a branch with a thousand different leaves on it, that so far is totally divorced from any observation.


Too many questions have accumulated. It is time for another Einstein to appear. Not only the discovery of a few "hidden variables" is needed, but also a completely new way of thinking of reality.

I liked the intuitive simplicity of Einstein's early model of the universe as a four-dimensional hypersphere, the center as the time-origin and the 3-D "surface" as our perceived universe. Now the String Theory idea of "branes" flapping around in 10-dimensional spaces repels me and provides no intuitive picture of reality.

Meanwhile, to get back to the subject of this thread: Randomness. Back when I was young and foolish, I was interested in gambling systems. To provide a sample of random events to test my ideas, I flipped a coin over a period of months for a total of 30,000 flips (I was a little compulsive). When I tabulated the results, I was surprised to find that the average length of "runs" in my sample was slightly longer than mathematically expected. Not much, but very statistically significant for a sample of that size. In other words, there seemed to be a slight tendency for a head to be followed by another head, a tail by another tail, etc.

Later, when I started working as a computer programmer (only large very expensive mainframes existed then), I gave up on gambling systems after testing my ideas on much larger simulated samples and found they all eventually failed. However, the statistical deviation in my original sample of coin flips continued to trouble me. I had used many different coins, and could think of no explanation for it. More recently, I decided to try the experiment again, but this time carefully turned the coin over each time before flipping it again. After only 3000 flips, I found that the average length of runs was now slightly shorter than statistically expected!!! Have you ever heard of such a result?

John

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Post BBCode URL - Right click and save to clipboard to use later in post Post 18: Sun Nov 06, 2011 4:25 pm
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I think it is relevant to take into consideration the idea that at any given moment, there are infinite factors determining how following events will be played out. Currently, we do not have a method for quantitatively measuring infinity. If this is true, then everything is to some degree random because we could never account for all the factors leading into how future events will occur.

Thus we could redefine randomness as: When something occurs for no reason that we can determine.

Now, if we decide to assume there is a fourth dimension, then it would imply a universe that's totality is based not only on the laws of time and space. In the same way that the 3rd dimension can be thought of as a transcendent sum of infinite 2nd dimensional existences pieced together, so could be the same for the 3rd dimension in relation to the 4th.

When we add the factor of depth to the two previous concepts of length and width, we get an increased amount of possible universes that equals infinity. Could a second dimensional being become aware of these new possibilities in the universe simply by being aware that there is something called depth, that transcends what it understood before about how it's decisions are made? Could we at some point become aware of infinite parallel universes by realizing another factor in our existence that transcends time and space?

Assuming there are these parallel universes that take our existence in different directions, is it also possible that we are, at any given moment, unknowingly choosing out of infinite possibilities ahead of us in time, and entering into new universes with their own infinite sets of probabilities. If we can't know how these decisions are being made, due to our ignorance of this new factor in the fourth dimension, then can our actions be seen as random?

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Post BBCode URL - Right click and save to clipboard to use later in post Post 19: Sun Nov 06, 2011 5:17 pm
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Crazee wrote:
I think it is relevant to take into consideration the idea that at any given moment, there are infinite factors determining how following events will be played out. Currently, we do not have a method for quantitatively measuring infinity. If this is true, then everything is to some degree random because we could never account for all the factors leading into how future events will occur.

Thus we could redefine randomness as: When something occurs for no reason that we can determine.

Now, if we decide to assume there is a fourth dimension, then it would imply a universe that's totality is based not only on the laws of time and space. In the same way that the 3rd dimension can be thought of as a transcendent sum of infinite 2nd dimensional existences pieced together, so could be the same for the 3rd dimension in relation to the 4th.

When we add the factor of depth to the two previous concepts of length and width, we get an increased amount of possible universes that equals infinity. Could a second dimensional being become aware of these new possibilities in the universe simply by being aware that there is something called depth, that transcends what it understood before about how it's decisions are made? Could we at some point become aware of infinite parallel universes by realizing another factor in our existence that transcends time and space?

Assuming there are these parallel universes that take our existence in different directions, is it also possible that we are, at any given moment, unknowingly choosing out of infinite possibilities ahead of us in time, and entering into new universes with their own infinite sets of probabilities. If we can't know how these decisions are being made, due to our ignorance of this new factor in the fourth dimension, then can our actions be seen as random?


Your idea of parallel 3-dimensional universes forming a larger 4-dimensional reality is similar to my understanding of the "Many Worlds" interpretation of Quantum Mechanics proposed by Everett in 1957. (This is not the same as the current Multiverse of String Theory). In this view, reality consists of an infinity of 3-D universes arranged like the pages of a book, in which each page represents a complete 3-D universe, and the "thickness" of the book is a fourth spatial dimension. (not the same as the 4th dimension traditionally reserved for time)

Slightly different versions of 3-D reality simutaneously exist in these side-by-side universes. When an observer makes an observation of a quantum event, it is not the "wave function" of his universe that instantly collapses faster than light to agree with his observation. Instead, it is his own conscious awareness that randomly synchronizes or locks on to a particular nearby universe which contains a particular result of his observation, one of the many possible results predicted by the probabilities of Quantum theory. All other possible results continue to "really" exist as "real" in their own universes.

In accordance with the probabilities calculated by Quantum theory, it is probable that his awareness will land in a nearby universe which is very similar to his old universe, except for a few microscopic quantum differences, but it is also possible but very improbable that his awareness could land in a distant universe which is very different. He could suddenly find himself to be a Klingon. He would not be aware of the change, since all his memories, perceptions, etc, would now come from his new Klingon 3-D brain, and he would have no access to his old memories.

In this idea, the observer is like the 2 dimensional flatlander described in the book, "Flatland" who is surprised to see the varying circular cross sections or 2-D "slices" of a 3-D sphere as it passes through his flat universe.

Most of this is my own speculation, and certainly not contained in Everett's theory. A little more far-out speculation would see us humans as merely 3-D cross sections or slices of larger 4-D entities existing in a larger 4-D universe.

John

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Post BBCode URL - Right click and save to clipboard to use later in post Post 20: Mon Feb 20, 2012 3:37 pm
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AquinasD wrote:
However, I think what is important to note is that randomness is scientifically unfalsifiable (...) Randomness is not observably distinguishable from events that occur in which we are simply unable to observe the antecedent causes of the consequent.

Science does not deal with an individual elementary event but with general patterns that can be found across large numbers of events - and physical experiments involve huge numbers of similar events, making possible to verify probability laws. So indeed it would not make scientific sense to question whether an individual elementary event with a couple of possible results, is random or not random, if this event was the only event that happened in the universe.
But, in the case we are facing, that is a very large number of observations to be compared with the values of their respective probabilities calculated from a well-defined theory, then the claim that those events obey those probability laws, has all qualities of a scientifically falsifiable claim.

Randomness can directly be falsified by expressing a rule that generates the given data. More generally and precisely, the claim of obedience of measured events to a given probability law, is the claim that "The optimal compression format of the file of observed data, is the format defined by this probability law".
Ifever it is false, its falsity can readily be shown by finding a set of observed data and another compression format (expressing another probability law) that makes this file significantly shorter (say, more than 100 bytes shorter, which should not be hard for a gigabytes long file if there really were hidden causes) than with the format of the first probability law.

Until now, the quantum probability law resisted quite well, at least in non-biological systems, and possibly observed deviations from this law (in parapsychology) are very small.
This is telling: randomness heavily exists in physics.

On the other hand, there is a mathematical theorem essentially stating that as long as no explicit rule could be found, the belief that some large random piece of data would in fact be following some unknown hidden law, is unfalsifiable. This theorem was discovered by G. Chaitin. I summed it up (with the proof) in my metaphysics page (just seach "Chaitin" there).

Quote:
Randomness is not observably distinguishable from events that occur in which we are simply unable to observe the antecedent causes of the consequent.

So what ? Of two things one:
Either the hidden causes produce a pattern of deviations of possibly observable results (= results of specially designed experiments able to display such deviations) away from the quantum probability law, in which case this pattern can be observed and tentatively expressed as new modified probability law (that may not be the ultimate one either, but already a proof that the first law was not a complete account of reality).
Or it doesn't produce any such pattern in any possible observation, in which case any speculation about it remains futile and sterile for any purpose.

ThatGirlAgain wrote:
As you say, the Copenhagen Interpretation cannot be used to claim that randomness is fundamental to reality. There might be hidden variables. (However the experiments based on Bell’s Theorem make it clear that hidden variables of a classical physics form are impossible. Non-classical variables are still possible. The world is definitely weird but not necessarily insane.)

What these experiments exactly say cannot be summed up in so few words. Just telling that "classical" variables are impossible while "non-classical" variables are possible, does not mean anything as it begs the question what is meant by "classical". To try to be more precise, it is a matter of whether this variable is local or non-local.

What it says (or at least what it would say if it was verified with concious observers many thousands of kilometers apart, each able to immediately observe his local subsystem of a correlated system faster than light speed communication between them) is that the measurement result of a physical system at a given place cannot be locally determined by a hidden property (a hidden variable) of the measured system (or even of the local [system+observer]) that is a local property, which means a property that has no ability to be affected by a distant event (the measurement of another system) faster than the speed of light. Nor can it even be an independent (local) random effect with fixed probabilities determined by such hidden local properties.
(Well I admit that the logical deduction of this result from possible observational verifications of quantum theory, is not completely rigorous as it assumes the possibility of a sudden free choice of what aspect of his system each observer will decide to measure, but... looking for a way around the conclusion here based on an assumed physical determinism of what observers would choose to measure, would be rather far-fetched).
Quote:
From what little I understand about the modern idea of "decoherence," it seems to be a pathetic attempt to save the idea of a collapsing wave function while avoiding the need for a conscious observer.

Decoherence is NOT an interpretation, but it is an effective physical property that can be deduced from quantum theory disregarding the choice of interpretation.

Its precise definition is :
A system S is said to have decohered with respect to a possible measurement M, if there will be no more difference on the probabilities of any future possible measurement of S, whether or not the wavefunction of S is assumed to be now already collapsed with respect to M.

In other words, a decoherence is NOT a spontaneous collapse, but it is the description of the circumstances where the question whether a collapse happened or not, becomes unverifiable, so that the "already collapsed" hypothesis becomes compatible with the predictions of quantum theory on future measurement results (while a collapse before decoherence would violate the predictions of quantum theory on future measurements).

However, this property of decoherence is an emergent property that only makes sense as a limit property of large systems instead of elementary ones, because it depends on which future measurements can remain possible or not in practice, and this is a fuzzy condition. It is not exactly an internal change, but an external irreversible loss of future opportunities to make measurements capable of deducing the past characters of the system expressed by components of the wavefunction that an hypothetical present collapse would destroy.

In practice, decoherence happens as soon as (but not only if) a measurement has been "physically processed", in the sense that we have a macroscopic delivery of the measured result, that is, when the information of the result is "out of the box" with many copies of this information escaping in the environment, so that it cannot be anymore securely hidden by any further operation.

Examples of physical circumstances that produce decoherence are already given here (even if we would not assume that cats have souls):
ThatGirlAgain wrote:
Interactions with other entities that cause irreversible changes is what is the alleged cause of the decoherence. (...) The cat does not die on the spot but is already dead and partly decomposed. Or the cat has been alive and drunk all the milk. A different world branch is selected retroactively depending on the kind of observation made?

In any case there is the issue that the status of the cat cannot be completely isolated from the outside world. The movement or lack thereof of the cat, even to the extent of breathing, will have immediate (subject to c) gravitational consequences for the entire universe.


Crazee wrote:
I think it is relevant to take into consideration the idea that at any given moment, there are infinite factors determining how following events will be played out. Currently, we do not have a method for quantitatively measuring infinity. If this is true, then everything is to some degree random because we could never account for all the factors leading into how future events will occur.

Quantum theory describes physical systems as locally (in every place of finite size at every given time) only having a finite (though large) "number of possible states" (with a concept of "number of possible states" that is a specifically quantum theoretical concept, but...). Thus any idea of a presence of an infinity of factors, must refer to non-physical factors, if by "physical" we mean the kind of states of physical systems that quantum theory describes. Of course you may imagine that there are more physical aspects of systems than those described by quantum theory, but well, such other physical causes remained undetected yet.
Crazee wrote:
Thus we could redefine randomness as: When something occurs for no reason that we can determine.

Indeed and just as JonhPaul already mentioned, this is an effective, non-metaphysical conception of randomness that is very important to the events of daily life, for example when you stumble on some preacher of a sect who tries to convince you that God has plans for your life and that your stumbling on him could not be a mere accident.

JohnPaul wrote:
I prefer to believe that the cat is neither alive nor dead, but that all possible versions of it continue to "really" exist, some of them alive and some dead, distributed in accordance with the probabilities derived from quantum theory, each in its own separate 3-D universe but all still part of a larger four-dimensional reality.

Imagine an experiment producing a linearly polarized photon, and its polarization is measured by some detector in another direction forming an arbitrary chosen angle with the direction of the arriving photon.
In other words, it is an experiment with exactly 2 possible results with the "same quality" (one bit of stored information in the detector) but theoretical probabilities have an arbitrary value other than 1/2 each.

Now can you make sense of the claim:
    «Both possible versions of the detector (or the larger system) after measurement, continue to "really" exist, one of them with "vertical" measured result and the other with "horizontal" measured result, distributed in accordance with the probabilities derived from quantum theory»

I think such a claim is logically inconsistent. In other words, the idea of "real existence" of all possible results, is logically incompatible with the conformity of the effective (observed) probabilities to those predicted by quantum theory.
Thus, that the experimental verification of this conformity, refutes the idea of the "real existence" of all possibilities. Unless of course you find a way to make sense of the claim that a given precise scenario has x times more reality than an other if x is an irrational number, but I fail to figure out one now.

Let's further push the examination of the thought experiment:

Note that anyway, any possible "difference of quality" of the final state of the detector between both possible results, remains independent of the angle between the directions of arrived and measured polarization; and even if you consider the whole system "emitter + detector", I fail to see how to consider any "difference of quality" between its 2 possible final states (making the one "more frequent" than the other), in such a way that this "difference of quality" depends on the configuration of whatever optical device that could have been on the way of the photon and that could have modified the direction of polarization, without itself keeping any trace of its interaction with the photon.

If a possibility is said to "more probably exist" than another as defined by the ratio of the numbers of possible "final states", then it all depends on the time at which you choose to stop the experiment and make the count of the number of possible "final states". You may as well decide to cheat by waiting longer (make more experiments...) in one case than in the other before doing the counting, so as to change the ratio of these numbers. Finally, I think such a metaphysical definition of "probability" turns out to be empty and incompatible with the effective (experimentally verifiable) meaning of "probability".
Quote:
Instead, it is his own conscious awareness that randomly synchronizes or locks on to a particular nearby universe which contains a particular result of his observation, one of the many possible results predicted by the probabilities of Quantum theory. All other possible results continue to "really" exist as "real" in their own universes.

I think these two sentences contradict each other, expressing two very different and incompatible interpretations of quantum theory. The first sentence precisely expresses my own view, that is the "conciousness causes collapse" interpretation, where conciousness is beyond physics.

The second sentence, claiming for an independent reality of all alternative possible results, gets conciousness out of the picture, or in other words, provides all possible results their own respective concious observers so as to make their respective "realities" worthy of that name. But if conciousness is divided (or multiplied) across all possibilities, then how can there still be anything "random", what is a probability, and how can it make any sense to claim that calculated probabilities are "correct" and can be or have been experimentally verified ?

My own view, the "conciousness causes collapse" interpretation which I expressed in my metaphysics page, is that physical objects are not essential beings, but the only real things are:
    - mathematical objects
    - concious events (including concious perceptions of the physical world)
So, alternative possibilities of a measurement only have a mathematical existence, as mathematical objects that received a mathematical number that is the value of the theoretical probability they were given at some time before the concious measurement happened.

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