Tuesday, April 8, 2008

Hidden Variables and the Seventh Dimension

In my recent entry "Imagining the Sixth Dimension", and its more expanded followup post "Time is a Direction", we talked about the concept of each dimension being at "right angles" to the one below, and we arrived at a way of imagining the sixth dimension that accounts for every branching timeline possible for our universe, including the ones that are not currently accessible to us from the fifth-dimensional ray creating our four-dimensional line. Now, here's a few quotes from an article by Mark Buchanan published in the March 22 2008 edition of New Scientist Magazine.

Quantum Randomness May Not Be Random

...most quantum researchers celebrate the notion that pure chance lies at the foundations of the universe.

However, a sizeable minority of physicists have long been pushing entirely the opposite view. They remain unconvinced that quantum theory depends on pure chance, and they shun the philosophical contortions of quantum weirdness. The world is not inherently random, they say, it only appears that way. Their response has been to develop quantum models that are deterministic, and that describe a world that has "objective" properties, whether or not we measure them. The problem is that such models have had flaws that many physicists consider fatal, such as inconsistencies with established theories.

Until now, that is. A series of recent papers show that the idea of a deterministic and objective universe is alive and kicking. At the very least, the notion that quantum theory put the nail in the coffin of determinism has been wildly overstated, says physicist Sheldon Goldstein of Rutgers University in New Jersey. He and a cadre of like-minded physicists have been pursuing an alternative quantum theory known as Bohmian mechanics, in which particles follow precise trajectories or paths through space and time, and the future is perfectly predictable from the past. "It's a reformulation of quantum theory that is not at all congenial to supposedly deep quantum philosophy," says Goldstein. "It's precise and objective - and deterministic."

...Goldstein and others have tried to develop modified versions of the theory... Their work began in the 1980s and 90s as part of an effort to develop Bohmian models that describe not only quantum particles but quantum fields as well, which provide the basic framework of all modern physics. In these models, the universe consists both of particles following precise trajectories and of continuous fields that, like classical magnetic or electric fields, also evolve in a deterministic way. Over the past decade, Goldstein, working with Dürr and physicist Nino Zanghi of the University of Genoa in Italy, has shown that this picture gives a consistent view of relativistic particle processes, while reproducing the accurate predictions of quantum field theory (Physical Review Letters, vol 93, p 090402).

The most promising result to come out of this framework was published last year by Ward Struyve and Hans Westman, both at the Perimeter Institute in Waterloo, Ontario, Canada. They developed a Bohmian model that matches one of the most accurate theories in the history of science - quantum electrodynamics, the theory of light and its interactions with charged particles. In fact, Struyve and Westman found that a number of Bohmian models can easily account for all such phenomena, while remaining fully deterministic (Proceedings of the Royal Society A, vol 463, p 3115).

...Goldstein and others have also solved another nagging problem for Bohmian models: elucidating how a deterministic theory can give rise to the fuzziness observed in quantum experiments in the first place. The uncertainty principle of quantum mechanics states that measuring the position of a quantum particle limits your knowledge of its momentum, and vice versa. The standard explanation is that the particle's state is undetermined until you measure it, but in Bohmian mechanics the state is always well defined. The trick, Goldstein says, is that measuring one variable stirs up uncertainty in the other due to interactions between the measuring device and the particle, in a way that matches the uncertainty principle.

In the early 1990s, Goldstein, Dürr and Zanghi were able to show that the statistical observations of quantum theory could reflect an "equilibrium" of underlying hidden variables. They found that in many circumstances it is natural to expect those hidden variables to evolve so as to produce that equilibrium, and thus quantum theory as we know it. But their work also suggested that in some situations the hidden variables might be out of equilibrium, in which case Bohmian predictions would differ from those of conventional quantum theory.

...The debate over whether the universe is random or deterministic is not likely to end before such experiments become possible. That won't stop physicists and philosophers from continuing to examine whether or not the logical structure of quantum theory demands randomness, or might instead rest on some deeper deterministic layer. In the latter case, predicting the future would be as simple as knowing the fundamental quantum rules and current conditions in enough detail. But even if we could do that, would we really want to? A deterministic universe might just be a little too boring.

The "Bohmian mechanics" described above refers to theories originated by physicist David Bohm, who Gevin Giorbran often quoted as having strong connections to both Gevin's and my own way of visualizing reality. Here's where this all aligns with what I've been saying with this project: Everett's Many Worlds Interpretation says that we are not collapsing the quantum wavefunction, we are merely observing the wave in one particular state out of the many that continue to exist. The David Deutsch team have proved that this is the case at both the quantum and the macro level. Here's the question that my way of visualizing reality helps to provide an answer for: if the underlying fabric of reality includes every possible different-initial-conditions universe, and all possible timelines for each of those possible universes, what is it that constrains our own universe, and keeps it from wandering off into the other parts of the "omniverse" where our version of physical reality becomes impossible? It's because we are constrained by our position within the seventh dimension (or, as some cosmologists say, it is because our 3D universe is embedded within a three-dimensional and a seven-dimensional brane).

If, as the Bohmian models suggest, there is an equilibrium state where hidden variables lie to create our seemingly random but ultimately predictable universe, then where would I suggest we can find those hidden variables? In the specifically located "point" in the seventh dimension, where every possible state for our particular universe can be found simultaneously, enfolded into the equilibrium that creates the specific conditions for the universe in which we live.

Enjoy the journey,

Rob Bryanton

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