The many-worlds interpretation (MWI) of quantum mechanics is currently experiencing a popular resurgence, propelled by such prominent and articulate physicists as Sean Carroll, David Deutsch, Max Tegmark, and Lev Vaidman. The consequences of MWI are mind-boggling: the spacetime universe of our experience is only one branch of an unimaginably fast-multiplying plethora of alternative universes held incommunicado. In this paper, we propose that the mass of Medusa's hair served up by MWI is due to a failure to embed the spacetime universe in the right space: spacetime is a slice of bread, not a splitting strand of pasta. By way of motivation, we first give a very simple presentation of Bell's inequality by comparing it to a ``quantum game show'', followed by a simple description of Aspect's 1985 experiment involving entangled photons which confirms the inequality. We interpret the paradoxical correlation between measurements as resulting from a process outside of spacetime that produces both the original entanglement and the measurements. This is followed by a brief presentation of MWI, and then by a pictorial comparison of the proposed process model and MWI. The final section lists a number of potential consequences of the model related to causality, determinism, free will, and consciousness, and points to further references that give a more in-depth and rigorous presentation of the process dimension model. The entire article is non-technical and requires no mathematical background other than high school mathematics and an understanding of basic concepts in probability. The physics involved in Aspect's experiment is also explained.
The many-worlds interpretation (MWI) of quantum mechanics is currently experiencing a popular resurgence, propelled by such prominent and articulate physicists as Sean Carroll, David Deutsch, Max Tegmark, and Lev Vaidman. The consequences of MWI are mind-boggling: the spacetime universe of our experience is only one branch of an unimaginably fast-multiplying plethora of alternative universes held incommunicado. In this paper, we propose that the mass of Medusa's hair served up by MWI is due to a failure to embed the spacetime universe in the right space: spacetime is a slice of bread, not a splitting strand of pasta. By way of motivation, we first give a very simple presentation of Bell's inequality by comparing it to a ``quantum game show'', followed by a simple description of Aspect's 1985 experiment involving entangled photons which confirms the inequality. We interpret the paradoxical correlation between measurements as resulting from a process outside of spacetime that produces both the original entanglement and the measurements. This is followed by a brief presentation of MWI, and then by a pictorial comparison of the proposed process model and MWI. The final section lists a number of potential consequences of the model related to causality, determinism, free will, and consciousness, and points to further references that give a more in-depth and rigorous presentation of the process dimension model. The entire article is non-technical and requires no mathematical background other than high school mathematics and an understanding of basic concepts in probability. The physics involved in Aspect's experiment is also explained.
n their contribution to this book, McQueen and Vaidman argue that common sense requires that explanations in physics be not only causal1 but also local. Their main claim is that the Many Worlds Interpretation (MWI) of quantum mechanics (originally due to Everett) provides local explanations of the outcomes of experiments that in other interpretations of quantum mechanics seem to require (some sort of) nonlocality. Particles in the MWI leave traces both in the world where they exist but also in other worlds in which they do not exist. So the explanation is said to be local because spacetime splits together with the particles so that there is no influence at space-like separation within a world, but the causal influence literally travels across ‘parallel’ worlds. This seems to stretch the concept of locality beyond common sense, if not beyond breaking point, even if one understands causation weakly in terms of counterfactual dependence rather than by straightforward physical interaction.
The Copenhagen interpretation of quantum entanglement experiments is at best incomplete, since the intermediate state induced by collapse of the wave function apparently depends upon the inertial rest frame in which the experiment is observed. While the Many Worlds Interpretation of Everett, MWI, avoids the issue of wave function collapse, it, too, is a casualty of the special theory of relativity. This requires all events in the universe, past, present and future, to be unique, as in the block universe picture, which rules out Everett style branching. The benefits of MWI may be retained, however, by postulating a multiverse of discrete, parallel, block universes which are identical to each other up to certain points in the MWI trunk before they diverge according to the MWI branching. The quantum probability of an event then emerges from the number of parallel universes in which the event happens divided by the total number of universes. This means that the total number of such universes is finite. Such a picture is more easily envisaged by thinking of it as a purely mathematical structure, as in the Mathematical Universe Hypothesis proposed by Tegmark. However, while Tegmark wished to avoid contamination from Goedelian self referential knots, not only does such contamination appear to be inevitable, it brings an unexpected benefit. The mathematical hierarchy required by the enigmatic footnote 48a in the paper by Goedel leads to an explanation for a unitary evolution of deterministic quantum rules across the multiverse while accounting for quantum uncertainty within an individual universe. Other aspects of this structure, called here the Plexus, are discussed, including awareness of existence and other questions raised by the hypothesis.
It is argued that the lesson we should learn from Bell's inequalities is not that quantum mechanics requires some kind of action at a distance, but that it leads us to believe in parallel worlds. Introduction Bell's work [1] led to a revolution in our understanding of nature. I remember attending my first physics conference, on “Microphysical Reality and Quantum Formalism,” in Urbino, 1985. Most of the talks were about Aspect's experiment [2] confirming the nonlocality of quantum mechanics based on experimental violations of Bell's inequalities. Although I did not share the skepticism of many speakers regarding the results of Aspect, I was not ready to accept that a local action in one place can instantaneously change anything at another place. So, while for the majority the lesson from Bell was that quantum mechanics requires some “spooky action at a distance”, I was led by Bell's result to an alternative revolutionary change in our view of nature. I saw no other way than accepting the manyworlds interpretation (MWI) of quantum mechanics [3, 4]. I shall start by presenting the Einstein–Podolsky–Rosen (EPR) [5] argument. Then I will present Bell's presented using the Greenberger–Horne–Zeilinger setup [6] in the form proposed by Mermin [7, 8]. The discussion of nonlocality will suggest that Bell's inequalities are the only manifestation of action at a distance in nature. The demonstration of the necessity of action at a distance will be done through a detailed analysis of the GHZ experiment. Then I shall show how multiple worlds resolve the problem of action at a distance. After discussing the issue of nonlocality in the MWI, I shall conclude by citing Bell's views on the MWI. EPR–Bell–GHZ The story of Bell cannot be told without first describing the EPR argument. Instead of following the historical route, I shall use the GHZ setup, which, in my view, is the clearest way to explain the EPR and Bell's discovery.
At present, there are two possible, and equally plausible, explanations for the physics of quantum measurement. The first explanation, known as the many-worlds interpretation, does not require any modification of quantum mechanics, and asserts that at the time of measurement the Universe splits into many branches, one branch for every possible alternative. The various branches do not interfere with each other because of decoherence, thus providing a picture broadly consistent with the observed Universe. The second explanation, which requires quantum mechanics to be modified from its presently known form, is that at the time of measurement the wave-function collapses into one of the possible alternatives. The two explanations are mutually exclusive, and up until now, no theoretical reasoning has been put forward to choose one explanation over the other. In this article, we provide an argument which implies that the collapse interpretation is favored over the many-worlds interpretation. Our starting point is the assertion (which we justify) that there ought to exist a reformulation of quantum mechanics which does not refer to a classical spacetime manifold. The need for such a reformulation implies that quantum theory becomes non-linear on the Planck mass/energy scale. Standard linear quantum mechanics is an approximation to this non-linear theory, valid at energy scales much smaller than the Planck scale. Using ideas based on noncommutative | >=
At present, there are two possible, and equally plausible, explanations for the physics of quantum measurement. The first explanation, known as the many-worlds interpretation, does not require any modification of quantum mechanics, and asserts that at the time of measurement the Universe splits into many branches, one branch for every possible alternative. The various branches do not interfere with each other because of decoherence, thus providing a picture broadly consistent with the observed Universe. The second explanation, which requires quantum mechanics to be modified from its presently known form, is that at the time of measurement the wavefunction collapses into one of the possible alternatives. The two explanations are mutually exclusive, and up until now, no theoretical reasoning has been put forward to choose one explanation over the other. In this article, we provide an argument which implies that the collapse interpretation is favored over the many-worlds interpretation. Our starting point is the assertion (which we justify) that there ought to exist a reformulation of quantum mechanics which does not refer to a classical spacetime manifold. The need for such a reformulation implies that quantum theory becomes nonlinear on the Planck mass/energy scale. Standard linear quantum mechanics is an approximation to this nonlinear theory, valid at energy scales much smaller than the Planck scale. Using ideas based on noncommutative differential geometry, we develop such a reformulation and derive a nonlinear Schrödinger equation, which can explain collapse of the wavefunction. We also obtain an expression for the lifetime of a quantum superposition. We suggest ideas for an experimental test of this model.
We present the case for a fixed, finite number of discrete, non-interacting, spatiotemporally finite, decohered spacetimes emerging from Everett’s Universal Wave Function, which we refer to as “Many Discrete Worlds” (MDW). No universes “split” in MDW. We argue that a Many Worlds Interpretation (MWI) branching structure that emerges after decoherence is equivalent to individual, weighted universes, each of which is divided into an immense number of discrete, identical copies, the number being proportional to the individual weighting. This ensures that repeated experiments within any such universe will demonstrate consistency with the Born rule. Each of these universes should be considered as complete, containing every decohered outcome over the entire extent of its spacetime, including every event/interaction occurring beyond any cosmological particle horizon for the entire duration of the given universe. We show that a countably infinite number of interactions needs an uncountably infinite number of universes, and show why measures such as the Lebesgue measure will fail in that case, with the result that the Born rule would not be demonstrable. This leads to the conclusion that the number of universes in the multiverse must be finite and, as a surprising corollary, that the universes themselves are finite, both in space and duration.