A Plague Upon the Oxford University Press!

Lightspeed: the ghostly aether and the race to measure the speed of light”, John C. H. Spence, ISBN 978-0-19-884196-8 (2022), Oxford University Press, Great Clarendon Street, Oxford OX2 6DP, England. 235 pages.

Oxford Uni is supposed to be one of the prime spawning grounds for Our Betters, people smarter than the rest of us … superior individuals who presume to have the right to run the world. OK, smart OUP guys – Why can’t you hire a competent editor?

To focus on Dr. Spence’s book – Where was the editor to ask the author the fundamental question: Who is the intended audience for this book? Where was the perceptive editor to recognize that Dr. Spence was the kind of author who would need a firm hand to help him keep on track? Where was the editor even to suggest basics, such as it might be helpful to place Figures in the sequence in which they are referred to in the text?

The book starts with the feeling of having been intended to follow in the highly successful footsteps of Dava Sobel’s “Longitude” – providing the lay reader with an overview of the principal personalities and the challenges they met in addressing an important issue for our societies. Sadly, the author could not resist wandering off the trail.

The essence of the tale is that light has been a topic of controversy since the time of the Ancient Greeks. Does it travel instantaneously or at finite speed? Is light a particle or a wave? Does light speed up or slow down when entering a denser medium? Does light require a medium (the aether, to use Dr. Spence’s preferred spelling)?

The story is peppered with well-known names – Galileo, Newton, Descartes, Faraday, Maxwell, Heaviside, Michelson – along with many others which are not so well known. Dr Spence outlines three main avenues to determine the speed of light – deduce it indirectly from astronomical observations: measure it directly in the laboratory; and calculate it from theory. But there are many by-ways and detours in Dr. Spence’s tale, some necessary and some not so necessary.

One of the less well-known names is the Dane Ole Roemer, who was the first to prove in 1676 that light had a finite speed, based on observations of the moons of Jupiter. However, it took separate advances in measuring distances within the Solar Systems before it was possible to quantify that speed. Other less well-known names include the Frenchmen Arago, Fizeau, and Cornu who made successively more precise direct measurements of the speed of light between about 1850 and 1875. The theoretical calculation of the speed of light was of course Scottish scientist James Clerk Maxwell in 1864.

Maxwell’s developments in the theory of electricity & magnetism led to an equation in which the speed of light was shown to be determined by two measurable parameters – permittivity (an electrical property) and permeability (a magnetic property). This equation implies that the speed of light in a vacuum is a constant, regardless of the speed of the light source towards or away from the observer. Very strange! Almost as strange as the fact that a totally empty vacuum has measurable electrical & magnetic characteristics! However, Dr. Spence does not focus much on those puzzles.

We can think of a ray of light as a self-licking ice cream cone. An electrical oscillation causes a magnetic oscillation, which in turn causes an electrical oscillation, thereby causing a magnetic oscillation, on & on – as the pulse of light proceeds frictionlessly at very high speed through the vast empty reaches of space. Much of Dr. Spence’s book focuses on the debate about whether there needed to be a medium – the aether – to support these electro-magnetic oscillations, analogous to the way in which the medium of the ocean allows water waves to propagate. The book also goes on to review how Maxwell’s theory led Hertz in 1887 to create longer wavelength electro-magnetic oscillations – the radio waves on which so much of modern life depends.

Unnecessarily, and probably unwisely, the author then delves into quantum mechanics and the debate over faster-than-light communication, including the controversy over the 1935 EPR (Einstein, Podolsky, Rosen) paper with what Einstein called “spooky action at a distance” and subsequent analyses of it, including Irishman John Stewart Bell’s 1964 theorem. By this point, the author has departed very far from the model of “Longitude”!

Complaints aside, there is a lot of interesting information in this book. One of the saddest tales is of the Frenchman Le Gentil who was part of the major international scientific effort (during yet another European war) to determine the Earth-Sun distance from the transits of Venus across the Sun predicted to occur in 1761 and 1769. Le Gentil was dispatched to India to make measurements of the 1761 transit, but arrived too late – delayed by war, disease, and other vicissitudes. He nobly decided to remain in India until the 1769 transit – but on the critical day, the sky was cloudy.

There is much else. What is the cause of stellar aberration? Who knew that Maxwell also analyzed the structure of the rings of Saturn? And anyone who wants to measure the speed of light for himself gets full instructions – all that is required is a microwave oven and some pizza dough. The frustration is that Dr. Spence’s book could have been so much better – if only the geniuses at the Oxford University Press had decided to involve a good editor in the process.

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A horse! A horse! My kingdom for a horse!

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I like your comments(ary); good stuff. I am immediately “re-caged” (aviation gyro speak) to Samo Burja’s writings on societal collapse.

“Red Flag” #1. What we used to do well, no one can do now.

Poor editing is a good example.

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That’s intuitive given that one wants a “photon” to conserve energy – exchanging energy between magnetic and electrical fields – but what about this diagram of an EM wave?

It has the appearance of energy coming into and going out of existence as the photon travels which, of course, is absurd. Not very intuitive that picture is it?

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From a picture like that, it’s easy to understand why the concept of the luminiferous æther was so compelling and persistent. It is easy to imagine a transverse wave propagating through a medium (for example, an oscillating string), in which case the momentum of the medium provides the kinetic energy at the node points. But without a medium, what’s to oscillate?

It’s intriguing that quantum field theory can be thought of in a way not unlike the æther. The electromagnetic field permeates all of space, transmits energy in a local fashion through oscillation, and when excited is observed as localised packets that we detect as photons and electrons.

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The exchange may be between actual (or kinetic) momentum and potential momentum. The Magnetic Vector Potential seems to be the key. It’s physical dimensions are potential momentum per charge. Then there is the Dual of the MVP: Electric Vector Potential.

The whole idea of an electromagnetic wave has the problem that, at least in special relativity, magnetism isn’t real. It is a manifestation of Lorentz contraction of charges in motion relative to the test charge.

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It may have been Mark Twain who said something like – The problem is not what we do not know. Rather the problem is what we know that just ain’t so!

Personally, I have merely scratched the surface of electromagnetism and quantum theory. However, it does seem that those theories require us to believe six impossible things before breakfast. And yet, it works!

There are a number of theories in various areas of science which have given the right answer – or at least an acceptable approximation – which have later turned out to have been built on the wrong foundation. Newton’s gravity and Carnot’s heat engine efficiency are standard examples. I can’t help wondering if future scientists will look back on our current theories of electromagnetism and shake their heads knowingly.

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It’s important to keep in mind that the phenomena and observations are what is real, and theories are just our way of compressing them into a more tractable and useful for prediction form by finding regularities in the raw data. Heisenberg and Schrödinger developed two seemingly very different theories of quantum mechanics which were later found to be equivalent and made the same predictions. Later, Freeman Dyson proved that the different formulations of quantum electrodynamics by Feynman and that of Schwinger and Tomonaga were equivalent. Which theory we end up using often depends upon how easy it is to work with and history—it doesn’t mean the other theory is less correct.

Maxwell’s original theory of electromagnetism was hideously complicated and difficult to work with. It was only after Oliver Heaviside and others reformulated the theory in terms of vector calculus that it assumed the beautiful form and predictive power we attribute to it today.

Much the same happened with Einstein’s general relativity, which was so cumbersome to investigate using Riemann’s tensor notation that Einstein adopted that the field lay dormant for decades until it was re-formulated using Cartan’s differential forms.

Those in the future may not regard our present theories as wrong, but cumbersome and obscuring the insights that a better-formulated theory may provide.

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I’ve been published in an OUP journal. So that tells you something.

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And even if they ARE shown to be wrong, they may have usefulness in their less complicated form. Newton’s gravity isn’t “right” but for a lot of simple things it works. ?Why do something more complicated when simple works.

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A quick read of the EPR paper (Phys Rev. 47, 777) finds no mention of “spooky action at a distance” nor does Wikiquote find such, though others have imputed such a view to him. EPR only implies anything like superluminal action at a distance if certain assumptions are made about reality, which assumptions were shown to be ill-advised by Prof. Bell and subsequent experimental tests of Bell’s Theorem. Messrs Einstein, Podolsky, and Rosen were exercised about the apparent lack of physical reality of properties such as momentum and spin if they are not measured. As Bell showed, that’s tough tacos: you don’t get to say the particle has such properties if you don’t measure them.

The only possible claim of spookiness would relate to superluminal communication, which is nowhere contained within quantum mechanics. No one, not even Einstein, finds action-at-a-distance especially spooky as long as it doesn’t travel faster than light. The Sun causes action at a distance upon the Earth and everyone’s cool with that; it takes about 8 minutes to get here.

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The EPR paper was published in 1935. The “spooky action at a distance” quote comes from a passage in a letter Einstein wrote to Max Born in 1947, which is collected in The Born-Einstein Letters. Einstein said, speaking of Born’s statistical approach to quantum mechanics, as translated to English, “I cannot seriously believe in it because the theory cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky action at a distance.” The original German phrase in the letter was “spukhafte Fernwirkung”, where the adjective can be translated as “ghostly” or (more colloquially) “spooky”.

The Nobel Prize in Physics for 2022 was shared by Alain Aspect, John F. Clauser, and Anton Zeilinger, who performed experiments with entangled photons that confirmed the Bell inequalities and demonstrated that no locally real theory predicts the experimental results from entangled particles.

The meaning of this is still debated. Many interpretations of quantum mechanics reject realism, stating that observables have no defined value until a measurement is made, while the de Broglie–Bohm theory preserves realism and determinism while being explicitly nonlocal. Neither interpretation permits faster-than-light communication.

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I read the Born-Einstein Letters when they were first published in the early 1970s but it’s been so long that I didn’t recall that quote. Einstein was certainly upset about QM and argued his case forcefully. I do recall that, at one point, Einstein accused Born of erecting a straw man and ceremoniously knocking it down. (going on memory)

Well, Born turned out to be right after all.

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Citing Wikiquote is a little like citing Wikipedia – Friends don’t let friends cite Wikianything! :slight_smile:

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In this discussion of the EPR paper, let’s not lose sight of the main point: Any competent editor would have redlined this section of the draft text as inappropriate for what was intended to be a broad market book on the rather interesting issue of how can human beings measure anything as fast as the speed of light?

Again, a plague upon the OUP for their failure to hire competent editors!

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It’s a useful starting point to track down references. It’s not the be-all & end-all, nor is it the Eighth Circle, though it is adjacent to it. I did consult other sources.

Moderation on all things.

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Just wait three quarters of a century! Here are movies, captured at a trillion frames per second using a femtosecond laser, which show the propagation of photons from a laser pulse striking macroscopic objects.

What is observable depends upon how clever is the observer.

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Exactly! That is why I am impressed by someone with very primitive equipment who came up with the clever idea of timing the orbit of Jupiter’s moons at one time of year, timing them again 6 months later, and using intelligence to deduce that the speed of light was finite. Or even someone who can develop a way to measure the speed of light using pizza dough and a microwave.

Once technology has advanced far enough (“standing on the shoulders of giants”), physics students in college & even high school can measure the speed of light in between getting cups of coffee.

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Or even better than pizza dough, marshmallows

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