It is quite amazing that the quantum measurement “problem” is still considered a quantum “problem” by a very large number of very smart people. Despite having been explained countless times by countless people in countless ways, somehow many very smart people are still making their careers out of being either for and against the problem of quantum measurement.
Determinate gravity relativity does not include quantum phase precursors and so quantum decoherence is simply not important for classical gravity outcomes. Somehow, gravity outcomes only involve coherent and not incoherent quantum phase. However, both coherent and incoherent quantum phase precursors are very important for quantum outcomes. Quantum phase decoherence and incoherence are at the very root of the quantum measurement “problem” as well as the many worlds interpretation.
While incoherent quantum phase precursors seem to play no role in the coherent quantum phase of the outcomes of determinant gravity relativity geodesics, quantum phase precursors and therefore quantum phase incoherence are key to the uncertainties of quantum outcomes. The Mermin device as well as its Stern-Gerlach effect both illustrate quantum phase superposition...
The Mermin device illustrates quantum phase superposition and correlation for two particles patterned after the Stern-Gerlach apparatus, which shows quantum spin superposition for just a single silver atom. The quantum measurement “problem” is all about quantum phase superposition and correlation and, of course, quantum phase decoherence. Quantum reality is all about quantum phase coherence and decoherence while the classical reality of gravity relativity only involves coherent quantum phase.
A single quantum particle can exist as an incoherent superposition of two quantum phase states before a measurement, but after a measurement, the particle becomes coherent with one phase or the other and so the wavefunction seems to have “collapsed” from incoherence into coherence. This is the essence of the quantum measurement “problem” because a particle spin only seems to have a particular spin reality after the measurement. Thus it seems the measurement suddenly collapsed the particle spin wavefunction, which made the particle quantum spin coherent and therefore classically real.
However, a quantum particle spin both before and after a measurement is a superposition of two spin states. A linear spin state is just a coherent superposition of a right and left circular polarization and so the measurement does not really collapse the particle spin into a coherent linear spin state.The measurement rather correlates particle quantum spin phase the measurement device quantum spin phase. This correlation is not instantaneous and rather occurs over a finite time from an uncorrelated superposition to a correlated superposition of particle and measurement device spin states.
The very typical approximation of a quantum measurement as instantaneous makes it seem like a wavefunction collapses suddenly into a single-spin state. Any actual quantum measurement, however, takes a finite time to create a coherent phase superposition from an incoherent one and that finite time involves the exchange of a large number of virtual photons. The typical statement of the measurement “problem” claims that the reality of a particular phase for a quantum state for a particle does not seem to exist until a measurement of the quantum phase of that particle.
Very smart people have been arguing about the nature of our quantum reality and quantum incoherence for over a hundred years. Really, no classical measurement is ever instantaneous either and so there is a dynamic evolution in any real measurement and a real measurement of a real particle’s quantum phase does not instantaneously change or collapse quantum phase at all.
However, the measurement problem is not the real quantum dilemma. The real quantum dilemma is about the uncertain nature of quantum precursors and causality given incoherent quantum phase versus that of classical coherent quantum phase causality, which does not include the incoherence of quantum phase. In our causal reality, every quantum outcome has a precursor and there are no supernatural or mystical precursors for any outcomes. However, we cannot always know about the incoherent precursor of a coherent quantum outcome.
Classically, all causal outcomes have knowable coherent precursors even those outcomes where we might not immediately know the precursor. Classical gravity relativity is therefore determinate and there are no unknowable precursors. Classical noise does typically limit classical knowledge, but classical noise is knowable up to the limit of the classical universe and therefore all determinate classical outcomes are in principle predictable in the universe limit. Classically, there are also no supernatural or mystical precursors for any classical outcomes.
Quantum outcomes, however, are inherently uncertain since quantum precursors can be in an incoherent superposition even though quantum outcomes are also causal and coherent and do have precursors. Therefore, an incoherent quantum phase superposition precursor is not precisely knowable beyond some well-defined uncertainty and therefore a coherent quantum outcome depends on the quantum phase of the measurement device as well as the particle measured. Therefore, incoherent quantum phase represents an unknowable precursor because, before a measurement, the coherent outcomes are only limited by a well-defined uncertainty.
With incoherent quantum phase precursors, then, it is simply not possible for Science to preclude the existence of supernatural or mystical effects for some coherent quantum phase outcomes. This really bothers many classical materialists because precursors with quantum phase incoherence are not precisely knowable, but that is the nature of our quantum reality.
The quantum measurement “problem” has been a dilemma ever since the discovery of quantum mechanics. All classical particles follow classical determinant geodesic paths in gravity relativity and so all classical geodesic path outcomes have knowable classical precursors. The earth orbits the sun and that orbit consists of all knowable precursors, but all quantum particles that have quantum phase incoherence have a well-defined uncertainty in quantum phase paths. Quantum phase incoherence means that some incoherent precursors exist in quantum phase superpositions that cause coherent outcomes with fundamentally unknowable incoherent precursors, albeit limited by a well-defined uncertainty.
The typical depiction of a superposition of quantum spin = ½ state for a particle starts with a superposition of spin-up and spin-down wavefunctions with coherent phases, so the incoherence of quantum phase is simply ignored. Measuring a spin state, though, always results in either coherent spin-up or spin-down state outcomes despite the existence of an incoherent superposition of state precursors to the measurement outcomes.
The quantum superposition state seems to have instantaneously collapsed or rephased into spin up or spin down upon measurement even though the quantum particle was in a superposition state of incoherent quantum phase prior to the measurement. In other words, measuring a coherent spin-up state does not then mean the particle was in the coherent spin-up state prior to the measurement. The coherent spin phase of the measurement along with many virtual photon exchanges are what transforms an incoherent superposition into a coherent spin-up state over some definite time.
However, the measured coherent linear spin state is also a superposition of two orthogonal spins as spin-right and spin-left circular phases. A superposition of circularly coherent phased spin-right and spin-left states is equivalent to coherent spin-up state. The action of the measurement transforms an incoherent superposition into a coherent linear or equivalent circular spin-right and spin-left superposition.
The measurement then transforms the incoherent circular phases of the two orthogonal spins into a coherent spin up as coherent rcp plus lcp. Instead of a state seeming to instantaneously disappear upon measurement, measurement simply polarizes or phases an incoherent spin superposition into a coherent superposition of spin states.
Gravity relativity does not yet include quantum phase incoherence because gravity force represents only coherent quantum phases of photon pairs. Gravity is similar to the always attractive coherent quantum phase of a dipole-induced-dipole dispersive force between a pair of neutral atoms, but dispersive forces vary as 1/r^6 power while gravity dispersion varies as 1/r^2. Gravity relativity is a coherent dispersive dipole-induced-dipole force, but now between the resultant quadrupoles of each atom wavefunction with the universe wavefunction. Thus the universe size fixes the dispersive attractive gravity force as an attraction of atom quadrupole biphotons or gravitons. Each atom’s biphoton quadrupole attracts all other atom biphoton quadrupoles and that defines the coherence of gravity force.
A single photon has spin = 1 and is always therefore in a superposition of two polarizations, {+1, -1} or {rcp, lcp} and so there are many different polarization wavefunction bases possible. One common basis is linear {parallel, perpendicular} and a second common basis is right circular/left circular, {rcp, lcp}.
A linear polarization is a superposition of rcp (phase1) + lcp (phase1) and rcp is a superposition of parallel (phase1) + perpendicular (phase1+90deg). There is a spin phase factor for each polarization and so a single light photon can actually be in an incoherent polarization state relative to other photons. Another photon of the same color entangled with the first photon has its same incoherent polarization state and this is coherence. That polarization entanglement will persist until there is a decoherence event of either or both photons.
A measurement is just such a decoherence event and the classical presumption is that the measurement outcome of a single photon polarization then reveals what the photon polarization precursor was before the measurement. However, our cruel quantum logic says the precise precursor polarization is actually unknowable and there are rather a very large, but limited, number of possible polarization precursors.
Measuring a single photon polarization only reveals its precursor as many possible, but still limited, superpositions. Thus, the action of one measurement seems to have created a new world from the old world with the measurement apparatus that made a single photon polarization coherent and that new world is different from the many possible precursor polarization worlds of an incoherent single photon polarization. How can that be mon ami? That is simply the way of our uncertain quantum world.
A photon polarizer or analyzer, which are the same device but used for different precursors, involves a complex dispersive interaction between a single photon electric field and a large number of bound electrons in an transparent medium. There are many different kinds of polarizers like the Glans-Thompsen, which has two calcite crystals with different orientations and each cut at a particular angle and glued together. An ideal polarizer transmits only linear parallel polarized photons at the interface and reflects only linear perpendicular polarized photons. Assuming the incoming light is incoherent, each photon dipole induces an image dipole in the bound electrons of the calcite crystals interface. Therefore, the polarizer actually changes the photon polarization just as much as the photon polarization changes the electron clouds of each calcite crystal.
Thus, the measurement of a single photon polarization affects the photon polarization in a very well defined way to produce a single photon polarization now coherent with the polarizer spin phase. While the polarizer will only polarize a single incoherent photon into one of two possible path, each photon will still be in a superposition of {rcp, lcp}. Therefore, it is not possible to know the precursor photon polarization any better than 50%.
