Retrocausality
Austin Fearnley
7 August 2024
I am writing this informal blog to explore the pros and cons of retrocausality at the microscopic quantum level. It will be informal as I intend to write one-off posts rather than attempt a coordinated effort making connections across posts.
In 1937, Einstein, Podolsky and Rosen published a paper because of their concerns about the implications of the recent developments in quantum theory. That concern is present in spirit in the work of John Bell and in the experimental efforts of Zwellinger et al who received the Nobel prize for physics in 2022. The loophole-free experiment results of 2015 and thereabouts appear to confirm that instantaneous action at a distance exists, at least for quantum particles. This indicates the importance of the Bell experiments as a key area in which new theories of physics may be required. Retrocausality may prove to be required theory rather than being an eccentric blind alley.
My own work focused on devising computer simulations of Bell experiments using hidden variables to act as particle polarisation vectors during the times of flight of particles in the experiments. Nothing I tried worked. The reason nothing worked is that Bell’s Theorem forbids particles maintaining local hidden variables and producing Quantum Mechanical theoretical correlations of results. A local hidden variable could be, for example, a polarisation vector of vector a during flight.
I next tried to simulate Malus’s Law for particles incident on a detector. I managed to achieve this by using a gyroscopic model of particle spins. This equates to an electron or photon having not a static polarisation vector but instead a dynamic vector precessing about the polarisation vector. The polarisation vector is therefore a nominal statistical average state and no more informative than say knowing that an average family has 2.4 children. To calculate experimental results, particle-at-a-ime, needs use of the dynamic vector at the time of the interaction of particle and detector, not the static polarisation vector.
Armed with the improved model of particle spin, which explains Malus’s empirical law, I tried to simulate The Bell correlation. With disapointment I found the correlation not to be as high as the QM value of 0.707. Nor even as high as the hidden variable, or classical or macroscopic experimental, value of 0.5. But as low as approximately 0.375.
Immediately after this disappointment I explored the idea of retrocausality. My model of retrocausality was successful in achieving the QM correlation of 0.707. But the method does not contravene Bell’s Theorem, as nothing can do that. Instead it shows that the retrocausal flight paths in the Bell experiment do not conform to the flight paths in a standard view of a Bell experiment. So the Bell Inequalites are bypassed rather than broken.
Retrocausality is an unfortunate name. My model does not allow people or objects to be sent back in time. Even quantum particles cannot be ‘sent’ back in time. They keep travelling in their natural time direction(s). My version of retrocausality seems to differ from other established versions.
Here are links to my most recent paper on retrocausality.
Retrocausality and the directions of time
http://vixra.org/abs/2312.0026 for the abstract
https://vixra.org/pdf/2312.0026v1.pdf for the paper
Superpositions
9 August 2024
Sabine Hossenfelder’s blog, ‘Backreaction’, at https://backreaction.blogspot.com/2024/03/quantum-gravity-breaks-causality-and.html raises questions, in my opinion, about the reality of superposition. My retrocausal model does not allow the same particle to be in two places at once. Sabine’s post seems to allow for a particle simultaneously having/sharing its mass at two separate and far flung places.
The Youtube of an interview with Roger Penrose: Many Worlds of Quantum Theory
https://www.youtube.com/watch?v=ycOO6JNCyEs&list=PLFJr3pJl27pIsZ2Um3TlpzZuzUrpeSvPA&index=19
also raises issues about superpositions in terms of the simultaneously dead and alive Schroedinger’s cat.
In another interview (https://www.youtube.com/watch?v=xsKuyuafEKc) I have recently seen, Penrose suggests that quantum mechanics needs to be amended to revise/moderate the idea of superpositions. QM is a statistical tool which deals in calculated probabilities of a particle being found in a particular state. Calculated probabilities are not subject to travelling at no greater than the speed of light. Material properties such as the spin state of a particle are, however, subject to the speed limit of the particle in special relativity. If QM was more ontological and less statistical, then the issue of Schrodinger’s cat would be resolved differently than by using Schrodinger’s equations. This relates to the once long-standing issue of whether QM is complete or not. The Bell experiments of circa 2015 seem to indicate that QM is complete. My version of retrocausality however allows for hidden variables of particles to exist and for a mechanism to apparently instantaneous impose a spin state on a distant entangled particle. But special relativity is obeyed in my retrocausal method.
Entanglement
18 August 2024
Entanglement makes it very difficult to deny the (ontic) reality of superpositions. Superpositions are straightforwardly understandable as statistical effects: such as a sock may be red or it may be green but we do not yet know which it is as we have not yet taken a look or, more generally in physics, made a measurement. It is important in the statistical interpretation of superposition that a sock always has its own colour before measurement. In the entanglement of socks (or particle spins), however, the colour of the sock is not a reality before measurement. That is, the observed colour of the sock, red or green, is not a property of the sock before it is observed. Instead, the sock before measurement has an entangled colour ‘red /or/ green’ which cannot be red or green until the instant of measurement. This meaning of quantum entanglement is taken to mean that the sock is ontically a mix of colours whereas a probabilistic interpretation is that ontically the sock is always either red or green and certainly not both. It seems strange that quantum mechanics is clearly a probabilistic system and yet has given rise to an ontic interpretation. ‘Red’ or ‘green’ equate to hidden variables. Hidden variables are not allowed because the colour of a sock is ‘red /or/ green’, not merely in a probabilistic sense but ontically too.
The ontic interpretation of superposed states within entanglement has been generally accepted because of Bell’s Theorem and the 2022 Nobel prize for loophole-free experiments confirming that Quantum Mechanics breaks Bell’s Theorem in the laboratory. Nothing, however, ought to break Bell’s Theorem as breaking Bell’s Theorem implies also breaking Bell’s Inequalities which is an unbreakable mathematical theorem of inequalities easily verified using a Venn Diagram. My retrocausal solution does not break the Bell Inequalities but the revised directions of particle flows through space and time avoids the strictures of the inequalities.
There are other routes to a solution of entanglement. One route is to deny that the Bell experiments are even now free of loopholes, despite the issue of Nobel prizes. Another route is to deny the mathematical proof of Bell’s Theorem. This denial, in my opinion, leads to getting ‘Lost in Maths’. Another route is to try computer simulations. I have tried this route and failed to break Bell’s Theorem. Then there is the route of superdeterminism, which I find weirder than quantum mechanics. And lastly is the route of retrocausality which I do not find weird as it fits in with my explanation of unified forces and my preon model.