Entanglement: A book review and some reflections

Science Editorial 5: June 16, 2009

(1) Book Review: Louisa Gilder: "The Age of Entanglement: When Quantum Physics Was Reborn" Borzoi Books (Alfred Knopf) , 2008

It is very difficult to write a review of a book written in such embarrassingly bad prose, which at the same time is so signal an accomplishment in terms of the work invested in it, and the historical importance of the events being related. One might it a paradigm manifestation of the Two Cultures Dilemma: a first-class history of modern science in the making, written in a kind of pidgin English.

Louisa Gilder generously acknowledges all the editorial help she received while writing it but, as with other explanatory books about modern science, even those coming from the presses of major publishers like Alfred Knopf, her editors must all have been asleep at the wheel. The style of "The Age of Entanglement" is a typical example of a certain of kind popular science writing. In this genre almost every noun must be preceded by a flashy, high energy adjective, most personal descriptions consist of one noun with its accompanying adjective, clichés abound, and all similes are exaggerated. Her contribution to this derivative canon is as bad as anything I've seen in recent years.

The problem appears to be that publishers, quite understandably repelled by the dull, repetitive, monotone character of most scientific research communications, feel that they must compensate for this in popular science writing by injecting that "zing", that "thrill of discovery", that "rush to the finish line" in sentence after sentence. I am unable to decide to my own satisfaction which stylistic convention is the more irritating.

In "The Age of Entanglement" these time-honored lapses in taste and judgment are compounded by the long procession of "historical reconstructions" that structure the narrative. The idea of presenting the recent history of a living science as a series of conversations based on the correspondence of , and interviews with, many of its principal animators, is excellent. Yet when, on page after page a phrase like :"Standing at the blackboard, X frowned", is followed a few lines later with something like: "Thinking about this, Y grinned", "frown" and "grin" following one after the other like Rosencrantz and Guildenstern, one begins to question its effectiveness.

As is so often the case, there are no equations in a book on a subject which demands, as a basic minimum, its most fundamental ones: the Uncertainty Principle, the Schrodinger Wave Equation, Bell's Inequality, etc. This has the unfortunate result of turning away the important class of readers who don't mind equations , including the scientists themselves.

Yet - (a paradox to rival even "entanglement"!) - the century-long history of quantum theory , together with all the recent developments and discoveries relating to entanglement, are portrayed in Louisa Gilder's memoir with such thoroughness and competence, that I would recommend it for the bookshelf of any scientist or layman interested in, or working in the relevant fields.

Her achievement is truly "incredible", the kind of word she overuses to the breaking point. In addition to portraying the intricacies of the slow advance of ideas from generation to generation, she also attempts to explain in words the mathematical concepts whose presentations in equations were censored by her well-meaning (?) publishers. The results are often turgid, convoluted, even confusing, but always impressive! In complete contrast to Sylvia Nasar in "A Beautiful Mind", when it comes to math and physics, Louisa Gilder really does know her stuff.

What I think must have happened is that Louisa Gilder, fully realizing that she'd received a bad literary education, knew that she couldn't write a book at the level of her subject. At this point she told herself:"I have a very important story to tell and I can't allow my inability as a writer to prevent me from conveying it. I'm sure that the editors at Borzoi Books will clean up the narrative and make it presentable." What she didn't realize is that there is no lazier class in the literary establishment than the editors of science popularizers. The logic seems to work as follows:

(1) Is the book written in acceptable language? Answer: No
(2) Will that hinder sales? Answer:Not by very much
(3) How much will it cost to do a good job of fixing it up? Too much. It may involve working with experts in the field who will charge a fortune.
(4) Conclusion: Tell the writer that everything is wonderfully written and pass it along to the printer!

If there is to be a second edition of "The Age of Entanglement my suggestion is that Louisa Gilder remove every adjective, every use of the words "frown" and "grin", every repetitive sentence and every simile, before sitting down with an editor to decide if or where to restore them . Yes, and a few equations please. They don't bite.

(2) Reading "The Age of Entanglement" has inspired me to indulge my fondness for speculations about entanglement , an endlessly renewable source of distraction for me over recent decades.

It is a reasonable hypothesis that, at the instant of the Big Bang, everything emerging from the cosmic singularity was entangled. Side-stepping Inflation and allowing for decoherence over billions of years, the greater part of all matter and radiation is still entangled. This may be enough to justify and explain the Cosmological Principle, namely that the universe is both isotropic and homogeneous.

Since 1900 there have been difficulties in the foundations of quantum theory arising from the interaction of observer and observed. These have led to profound differences of interpretation, particularly with regards to the roles of chance and determinism in the phenomenal world. Ideas such as Bohr's Complementarity , Bohm's Hidden Variables and even Everett's Many Worlds have been advanced to in defense of a deterministic, indeed a Newtonian universe-view of cause-and-effect.

In contrast, the amplitudes of Feynman's QED situate everything in the real of pure probability, the appearance of determinism being seen as the by-product of massive cancellations of these amplitudes. This viewpoint is carried even further with the Feynman Integral, the key concept of Topological Quantum Field Theory.

Lying somewhere between classical determinism and pure chance one finds John von Neumann's image of the "collapse of the wave packet". This makes the particle (wave) real at the moment of observation through the instantaneous collapse, throughout the entire universe of the probability wave. While on the one hand, creating something "real" or "tangible" it also creates, and ( instantly and everywhere) propagates uncertainty where there was none before. (It has been argued that this "collapse" is a particularly inept mixed metaphor, a way of picturing what is essentially a calculating device as a real phenomenon in the universe).

This is very unsatisfactory if one wants to posit the existence of a real universe apart from your, mine, his or her observations, will or intentions. After all, if you collapse the wave packet at a certain place by observing it, does not the fact that I did no such thing mean that I can continue to treat the "wave packet" at that point as "uncollapsed", whatever your observations may be? Is the "collapse" a real thing, apart from the observer who notices it? Such considerations entered, of course, into the construction of the famous thought experiment of Rosen, Podolsky and Einstein. (Placing Einstein at the end of the list should offend no-one. Recall the Jewish joke about the guest of honor who arrives late and is seated at the foot of the table. Explains the host: "The head of the table is where he's sitting.")

This leads one to try to identify phenomena lying outside our observations , from which the Uncertainty Principle, wave/particle dualism and the Schrodinger equation could be derived as consequences or corollaries. I speculate that one such phenomenon may be "entanglement". The quantum states of particles or photons created in opposite pairs will be entangled, quite apart from our observations, over all space and time until they are observed. Entanglement actually "re-unites" a universe that has been, metaphorically, "torn apart", first by Relativity (the causal independence of distant regions of space), then by quantum theory (The Uncertainty Principle).

I therefore propose that theorists look into the possibility of developing all of quantum mechanics from entanglement as the fundamental binding phenomenon of the universe! How does one set out to do something like this? Normally "entanglement" refers to correlated behavior between two entities originating from the same source. How is it operative in individual, isolated observations?

Such enterprises always necessitate a return to the sources. Anything observable as a particle is also observable as a wave. The Schrodinger "wave" of this wave/particle is spread out, at any instant, over all of space. However the "wave" of the wave/particle is not, in the same way that a front of light waves emanating from a candle is limited in the distance it can travel in a given time by the speed of light. But the "probability wave" of Schrodinger is everywhere. In fact, entanglement is just one way to make this explicit.

Yet, if all Schrodinger waves are instantly present at all points of space, one has "entanglement" of all things at every one of these points. For example, right here in the room I am working in, there is a non-vanishing probability that absolutely everything in the universe will spontaneously arrive here at once, with all the gravitational, electro-magnetic and other interactions that inevitably arise when they come close together. All matter, radiation and forces are simultaneously present here with a vanishing but non-zero probability. Hence all things are entangled , not just pair-particles.

Of course this makes a mockery of Relativity - it is pure Leibniz, unimpaired by any barriers such as the one imposed on the speed of light. And any interaction of particles "collapses" the wave packet. In particular, all "collisions" propagate in the form of a disturbance in the Schrodinger function, instantly over all space.

In the formalism of Quantum Field Theory, Nature itself is a gigantic tensor product of spin manifolds. Fields themselves are quantized; the quantum operators that represent them are all spin operators. Spin operators and spin vectors, or "spinors" do not follow the rules of a Euclidean geometry, or a non-Eucliean geometry, or even Minkowski space-time. They are elements of spin manifolds, and of their tensor products. Therefore, if one wishes to derive classical quantum mechanics from entanglement, one must begin by deriving Euclidean geometry from spinors and spin manifolds. This, I gather, was the objective of Penrose with his spin networks. (More reading and study on my part I'm afraid!)

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