The measurement problem in quantum mechanics is the unresolved problem of how (or if) wavefunction collapse occurs. The inability to observe this process directly has given rise to different interpretations of quantum mechanics, and poses a key set of questions that each interpretation must answer. The wavefunction in quantum mechanics evolves according to the Schrödinger equation into a linear superposition of different states, but actual measurements always find the physical system in a definite state. Any future evolution is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the process under examination. Whatever that "something" may be does not appear to be explained by the basic theory.

To express matters differently (to paraphrase Steven Weinberg [1][2]), the wave function evolves deterministically – knowing the wave function at one moment, the Schrödinger equation determines the wave function at any later time. If observers and their measuring apparatus are themselves described by a deterministic wave function, why can we not predict precise results for measurements, but only probabilities? As a general question: How can one establish a correspondence between quantum and classical reality?

The problem of induction is the philosophical question of whether inductive reasoning leads to knowledge. That is, what is the justification for either:

1 - generalizing about the properties of a class of objects based on some number of observations of particular instances of that class (for example, the inference that "all swans we have seen are white, and therefore all swans are white," before the discovery of black swans) or

2 - presupposing that a sequence of events in the future will occur as it always has in the past (for example, that the laws of physics will hold as they have always been observed to hold).

...

In inductive reasoning, one makes a series of observations and infers a new claim based on them. For instance, from a series of observations that at sea-level (approximately 14.7 psi, or 101 kPa) water freezes at 0°C (32°F), it seems valid to infer that the next sample of water will do the same, or that, in general, at sea-level water freezes at 0°C. That the next sample of water freezes under those conditions merely adds to the series of observations. First, it is not certain, regardless of the number of observations, that water always freezes at 0°C at sea-level. To be certain, it must be known that the law of nature is immutable. Second, the observations themselves do not establish the validity of inductive reasoning, except inductively.

The following idea characterises the relative independence of objects far apart in space A and B: external influence on A has no direct influence on B; this is known as the Principle of Local Action, which is used consistently only in field theory. If this axiom were to be completely abolished, the idea of the existence of quasienclosed systems, and thereby the postulation of laws which can be checked empirically in the accepted sense, would become impossible.

In physics, the principle of locality states that an object is influenced directly only by its immediate surroundings. Experiments have shown that quantum mechanically entangled particles must violate either the principle of locality or the form of philosophical realism known as counterfactual definiteness.

Einstein's view
[edit]EPR Paradox
Albert Einstein felt that there was something fundamentally incorrect with quantum mechanics since it predicted violations of locality. In a famous paper he and his co-authors articulated the Einstein-Podolsky-Rosen Paradox. Thirty years later John Stewart Bell responded with a paper which stated (paraphrased) that no physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics (Bell's theorem).

[edit] Philosophical view
Einstein assumed that principle of locality was necessary, and there could be no violations of it. He said[1]:

“ The following idea characterises the relative independence of objects far apart in space A and B: external influence on A has no direct influence on B; this is known as the Principle of Local Action, which is used consistently only in field theory. If this axiom were to be completely abolished, the idea of the existence of quasienclosed systems, and thereby the postulation of laws which can be checked empirically in the accepted sense, would become impossible. ”

[edit] Local realism
Local realism is the combination of the principle of locality with the "realistic" assumption that all objects must objectively have pre-existing values for any possible measurement before these measurements are made. Einstein liked to say that the Moon is "out there" even when no one is observing it.

[edit] Realism
Realism in the sense used by physicists does not directly equate to realism in metaphysics.[2] The latter is the claim that there is in some sense a mind-independent world. Even if the results of a possible measurement do not pre-exist the measurement, that does not mean they are the creation of the observer (as in the "consciousness causes collapse" interpretation of quantum mechanics).[citation needed] Furthermore, a mind-independent property does not have to be the value of some physical variable such as position or momentum. A property can be dispositional, i.e. it can be a tendency, in the way that glass objects tend to break, or are disposed to break, even if they do not actually break. Likewise, the mind-independent properties of quantum systems could consist of a tendency to respond to certain measurements with certain values with some probability.[3] Such an ontology would be metaphysically realistic without being realistic in the physicist's sense of "local realism" (which would require that single value be produced with certainty).

Local realism is a significant feature of classical mechanics, general relativity and Maxwell's theory, but quantum mechanics largely rejects this principle due to the presence of distant quantum entanglements, most clearly demonstrated by the EPR paradox and quantified by Bell's inequalities.[4] Any theory, like quantum mechanics, that violates Bell's inequalities must abandon either local realism or counterfactual definiteness. (Some physicists dispute that experiments have demonstrated Bell's violations, on the grounds that the sub-class of inhomogeneous Bell inequalities has not been tested or other experimental limitations). Different interpretations of quantum mechanics reject different parts of local realism and/or counterfactual definiteness.

1) Realism: The doctrine that regularities in observed phenomena are cause by some physical reality whose existence is independant of human observers.

Russell begins by exploring the twin concepts of appearance and reality. Empiricists like Russell believe that all knowledge is ultimately derived from our sensory perceptions of the world around us. Individual perception, however, is easily affected and prone to error. If three people—one who’s had three martinis, one with a heavy fever, and one who’s color-blind—look at the same table, chances are they’ll each see the same object somewhat differently. Submerge the same table underwater, or set it behind a wavy pane of glass, and once again the table will look different. There is, then, a distinction to be made between appearance and reality. If perception is so variable, what can it actually tell us about the stable, real object we assume lies behind it?

Russell coined the term “sense-data” in his attempt to discern the relationship between appearance and reality. Sense-data are the particular things we perceive during the act of sensation. When you walk into a café, the smell of the coffee, the redness of the awning, and the heat from the radiator are all examples of sense-data. Sense-data are the mental images (visual as well as auditory, olfactory, tactile, and gustatory) we receive from a given object in the physical world. As we can see from the table example, the same object can produce variable sense-data. Sense-data are related to the physical objects they represent, but the exact nature of this relationship is unclear. The skeptical argument contends that sense-data tell us nothing about the reality of the object. Russell had a commonsense take on the matter: while he understood the skeptical arguments, he found no reason to believe them. A hundred different viewers may have a thousand different kinds of sense-data for a given table, yet each agrees that they are looking at the same table. This consistency suggests, to Russell, that we must at least believe in the existence of a single, particular, real table. To this “instinctive” belief, Russell also adds the hypothesis that physical objects cause the sense-data we receive and therefore correspond to them in some significant way.

During the act of sensation (i.e., the exercising of our five senses), we receive and process the sense-data produced by physical objects in our vicinity. The knowledge we gain during this process Russell calls “perceptual knowledge”—knowledge gained through experience. In contrast, Russell believes we are also in possession of certain kinds of a priori knowledge. These include the self-evident rules of logic, most important, and those of mathematics. Perceptual knowledge (the knowledge of things) and a priori knowledge (the knowledge of truths) work in concert: the first gives us empirical data, and the second tells us how to process that data.

Russell further divides human knowledge into knowledge by acquaintance and knowledge by description. To be acquainted with something is to be directly and immediately aware of it, without the action of an intermediary. When you sit on a red plastic chair, you become acquainted with lots of sense-data associated with that chair. You know its redness, its smoothness, its coolness, and its hardness. But to know that this thing is called a “chair” and that it’s often found in the company of other “chairs” and something called a “table” requires more than just direct, immediate acquaintance with the physical object. To know all that requires us to make inferences, based on our general knowledge of facts and on our acquaintance with other similar objects. This kind of knowledge is derivative, and Russell terms it “knowledge by description.” For instance, most of us know only by description that Everest is the tallest mountain in the world. Few of us have actually been there, so we have to rely on the testimony of others to “know” that fact. Indeed, to truly be acquainted with the fact of Everest’s superior height, one would have to visit and measure all the mountains in the world. It’s probably safe to say, then, that no one is truly acquainted with that particular piece of knowledge.

Just as we can know objects either immediately or derivatively, we can also know truths immediately or derivatively. Russell defines immediate knowledge of truths as intuitive truths. These are concepts that, to Russell, are so clearly self-evident that we just know they must be true. “1 + 1 = 2” is an example of such a self-evident truth. Derivative knowledge of truths involves deduction and inference from immediate, self-evident truths.

All knowledge is, in Russell’s view, built on acquaintance. Without knowledge by description, however, we would never pass beyond the limits of our own individual experience. Thus, just like perceptual and a priori knowledge, knowledge by acquaintance and knowledge by description work together to create a totality of human knowledge.

Originally posted by Conclusion
reply to post by OnceReturned

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1) Realism: The doctrine that regularities in observed phenomena are cause by some physical reality whose existence is independant of human observers.

Yes. What about non-physical reality. Lets take thought for instance. Only the independent human observer can observe it in it's truest form. It is non-physical. That means that a non-physical reality exists also.

An epistemological paradigm shift was called a scientific revolution by epistemologist and historian of science Thomas Kuhn in his book The Structure of Scientific Revolutions.

A scientific revolution occurs, according to Kuhn, when scientists encounter anomalies which cannot be explained by the universally accepted paradigm within which scientific progress has thereto been made. The paradigm, in Kuhn's view, is not simply the current theory, but the entire worldview in which it exists, and all of the implications which come with it. It is based on features of landscape of knowledge that scientists can identify around them. There are anomalies for all paradigms, Kuhn maintained, that are brushed away as acceptable levels of error, or simply ignored and not dealt with (a principal argument Kuhn uses to reject Karl Popper's model of falsifiability as the key force involved in scientific change). Rather, according to Kuhn, anomalies have various levels of significance to the practitioners of science at the time. To put it in the context of early 20th century physics, some scientists found the problems with calculating Mercury's perihelion more troubling than the Michelson-Morley experiment results, and some the other way around. Kuhn's model of scientific change differs here, and in many places, from that of the logical positivists in that it puts an enhanced emphasis on the individual humans involved as scientists, rather than abstracting science into a purely logical or philosophical venture.

When enough significant anomalies have accrued against a current paradigm, the scientific discipline is thrown into a state of crisis, according to Kuhn. During this crisis, new ideas, perhaps ones previously discarded, are tried. Eventually a new paradigm is formed, which gains its own new followers, and an intellectual "battle" takes place between the followers of the new paradigm and the hold-outs of the old paradigm. Again, for early 20th century physics, the transition between the Maxwellian electromagnetic worldview and the Einsteinian Relativistic worldview was neither instantaneous nor calm, and instead involved a protracted set of "attacks," both with empirical data as well as rhetorical or philosophical arguments, by both sides, with the Einsteinian theory winning out in the long-run. Again, the weighing of evidence and importance of new data was fit through the human sieve: some scientists found the simplicity of Einstein's equations to be most compelling, while some found them more complicated than the notion of Maxwell's aether which they banished. Some found Eddington's photographs of light bending around the sun to be compelling, some questioned their accuracy and meaning. Sometimes the convincing force is just time itself and the human toll it takes, Kuhn said, using a quote from Max Planck: "a new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."

After a given discipline has changed from one paradigm to another, this is called, in Kuhn's terminology, a scientific revolution or a paradigm shift. It is often this final conclusion, the result of the long process, that is meant when the term paradigm shift is used colloquially: simply the (often radical) change of worldview, without reference to the specificities of Kuhn's historical argument.

My hope is that these philosophical problems will manifest themselves experimentally.

...these assumptions are built into the way we have been designed by evolution to experience and interact with our environment....

...,but we do not abandon it; we know it is still valid nearly all the time, so we keep it.