The mainstream textbooks of quantum mechanics explains the quantum state collapses into an eigenstate in the measurement, while other explanations such as hidden variables and multi-universe deny the collapsing. Here we propose an ideal thinking experiment on measuring the spin of an electron with 3 steps. It is simple and straightforward, in short, to measure a spin-up electron in x-axis, and then in z-axis. Whether there is a collapsing predicts different results of the experiment. The future realistic experiment will show the quantum state collapses or not in the measurement.
The mainstream textbooks of quantum mechanics explains the quantum state collapses into an eigenstate in the measurement, while other explanations such as hidden variables and multi-universe deny the collapsing. Here we propose an ideal thinking experiment on measuring the spin of an electron with 3 steps. It is simple and straightforward, in short, to measure a spin-up electron in x-axis, and then in z-axis. Whether there is a collapsing predicts different results of the experiment. The future realistic experiment will show the quantum state collapses or not in the measurement.
It is well known that electron spin is quantized, and is measured to be either spin up or spin down in a magnetic field, as was first demonstrated in the classic Stern-Gerlach experiment almost 100 years ago. However, it is also believed that a quantum spin may be indeterminate until it is measured, being in a quantum superposition of the two quantum states. On the contrary, I propose (based on a locally realistic spin-quantized picture of quantum waves) that an electron quantum state is always either spin up or spin down, but is never in a superposition of the two. This concept should be directly testable using a two-stage Stern-Gerlach experiment, similar to that presented in standard quantum textbooks, but apparently never carried out experimentally. This experiment should be straightforward using modern atomic beam laboratory equipment. If successful, this could lead to a serious review of quantum foundations, as well as a new set of practical applications. In particular, a binary storage or logic element based on quantum spin should continue to work down to the atomic scale. This should enable computer memories with orders of magnitude greater density than those based on conventional magnetic memories. 2
The measurement problem is to explain why a system which is in a linear combination of states appears, upon measurement, to be in just one of those states. The solution given here is to first show that if one assumes linear, unitary, no collapse, no particle quantum mechanics, the different versions of reality are completely isolated from each other. This then implies only the eigenstates appropriate to the measurement setup will be perceived. In a Stern-Gerlach experiment, for example, only spin up or spin down will be perceived, but never a combination of the two.
The double-slit (gedanken-) experiment is the most famous experiment in quantum theory (QT).The explanation of the strange behavior of the electron in this experiment is used as a key example in QT in general.The description of the experiment includes a rationalization of when in quantum mechanics interference occurs and (most importantly) when it "collapses".The aforementioned rule, here called the "interference collapse rule", is contained in almost all textbooks of QT with only slight variations.However, this rule makes sense only with additional assumptions which apparently are not generally agreed upon among physicists.The paper proposes an improved interference collapse rule that connects the interference collapse to the QT measurement and a functional interpretation of QT measurement.
The nature of electron spin has presented an enigma right from the beginning of quantum mechanics. We suggest that a simple realistic picture of a real coherently rotating vector field can account for both the Schrodinger equation and electron spin in a consistent manner. Such a rotating field carries distributed angular momentum and energy in the same way as a circularly polarized electromagnetic wave. We derive the Schrodinger equation from the relativistic Klein-Gordon Equation, where the complex wave function maps onto a fixed-axis real rotating vector. Such a realistic picture can also explain the Stern-Gerlach experiment which first identified electron spin. Remarkably, the predictions of a two-stage Stern-Gerlach experiment within this realistic picture differ from those of the orthodox quantum superposition approach. This two-stage experiment has not actually been done, and could provide insights into the limits of realistic models. This realistic picture also avoids quantum paradoxes and enables realistic explanations for a variety of quantum phenomena.
Local realism is causation by ordinary causal signals. What we mean by ordinary is this. First, these signals have fully determinate properties, whether measured or not. Second, they can only cause effects precisely at the spacetime locality of their physical existence. By contrast, as Einstein famously observed, quantum causal signals are spooky because they can cause effects where they do not in fact exist. Indeed, the only evidence that quantum causal signals possess any physical existence at all is that they seem to explain every effect you could ever measure. Unless you think about it. Take the simplest case: One photon, one spin measurement, up or down. The quantum explanation is essentially that we draw the answer from a bag that contains no answers such that physical reality obtains precisely from its own absence. This is known as the problem. But the problem is obviously not measurement. The problem is that quantum theory has literally no explanation for any specific measurement result. On the other hand, local realism does. Spin Up and Spin Down for photons must, at the end of the day, be analogous to Heads Up and Heads Down for ordinary fair coins. The quantum counterclaim, here, is that there is no compelling solution set of local hidden variables that makes this analogy work for an EPR experiment. Furthermore, many claim that the Bell inequality rules out any such solution set. On the other hand, anyone who thinks that the Bell inequality has some single uncontested meaning has not been reading the literature. The paper noted below claims both to provide local hidden variables that constitute a compelling local realistic solution for an EPR experiment and to explain how such solutions have been falsely denied. See viXra:1704.0078 - Local Realism Explains Bell Violations - for a demonstration that all empirical evidence taken to support quantum theory over local realism plausibly does the reverse. The article comprises 8 pages, 4 figures, 6 equations, 32 references, a graph of testable predictions, and two paragraphs that purport to expose how the Bell inequality misrepresents the local realistic predictions for the EPR experiment. Thoughtful feedback appreciated (apyake@gmail.com).
Long ago, Bohr, Pauli, and Mott argued that it is not, in principle, possible to measure the spin components of a free electron. One can try to use a Stern-Gerlach type of device, but the finite size of the beam results in an uncertainty of the splitting force that is comparable with the gradient force. The result is that no definite spin measurement can be made. Recently there has been a revival of interest in this problem, and we will present our own analysis and quantum-mechanical wave-packet calculations which suggest that a spin measurement is possible for a careful choice of initial conditions.