Ars Technica: Two experiments on entangled photons have forced the photons to display both their wave-like and particle-like properties. Normally, an observation that reveals the wave-like properties prevents later observations from showing the particle-like properties—and vice versa. In both experiments, polarized photons were sent through a device where they initially encountered a beam splitter giving them equal chance to take either of two paths. On one of the paths, the polarization is rotated, and mirrors redirect both paths toward an intersection with two detectors beyond. If the intersection does not have a second beam splitter in place, both detectors click with equal frequency, because the photons behave like particles. If there is a beam splitter in the intersection, the photons behave like waves, travel down both paths, and interfere with themselves, resulting in only one of the detectors registering hits. In one of the experiments, measurements of one of the entangled photons after the first had been through the device could determine whether the first had encountered the second beam splitter or not. The other experiment manipulated the polarization of the photons in ways that allowed them to control whether the first photon was more wave-like or more particle-like.
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Oops! This is the gramatically correct version of my comments. Ignore my previous version.
Perhaps causality is absolutely strict and the way the particle state is measured determines how the later measurement will come out. I believe in an all knowing and all powerful GOD who knows the precise future as it will unfold. Either we accept such strict determinism or we must accept that GOD does not know the future. Thus, perhaps a new definition of human free will is necessary.
Alternatively, all locally located and adjacent systems are entangled in such a way that a definitive quantum measurement brings out the results of the entanglement or amplifies the probability of a second measurement which would otherwise be viewed as violating causality.
Yet another idea is that entangled particles have internal ticks or modes such that the second measurement has many degrees of freedom in its potentiality but only those specific degrees are manefestable based on how the first measurement proceeded. Out of say an ensemble of possible future measurements which would initially appear totally and freely selectable by nature, there are perhaps an infinity scrapper of non-allowed measurements which the outcome of the first measurement would not permit. These two sets of possible latter measurements would be intermixed in terms of polarization, and admixtures of wave and particle states.
Regarding free will being relegated to strict determinism, perhaps such is not an issue in paradigms where this life’s tribulations and crosses are viewed as learning experiences for what always comes next. Even the purpose of Hell in the absolute plan in GOD’s Divine Economy is not known in an absolutely exhaustive manner commensurate with absolute metaphysical truth as known by or determined by GOD by we humans.
Einstein did indeed say GOD does not play dice, and I am betting that he is right.
Here is a simpler experiment that shows both particle and wave aspects of light at the same time: http://arxiv.org/ftp/quant-ph/papers/0702/0702188.pdf
Basically, the 2-slit, single-photon (at a time) experiment is enhanced by the following:
1) A lens following the slits images each slit onto its own photomultiplier tube. That way, which slit a photon comes through is recorded.
2) A grid of wires is placed after the slits, but before the above lens. The wires are spaced the same as the interference pattern would be at that distance. This could be a single wire also.
A)The photomultiplier tubes record each photon and which slit it passed through — showing the particle nature of light.
B)The total count rate depends on whether the wire(s) are positioned at the peaks or nulls of the interference pattern, showing the wave nature of light. (If the rate is plotted vs position of the wire, the diffraction pattern can be mapped.)
Both A and B are measured simultaneously, thus disproving the version of the Complementarity Principle that holds that only particle or wave aspects can be manifested in a single experiment, but never both at once. This principle is sometimes stated (as in Feynman’s text) as “anything that determines which slit passed the photon will destroy the interference pattern”.
Fascinating that this experiment wasn’t thought of until 2004, even though it could have been done anytime in the last 70 years (photomultiplier tubes were invented in 1934)..