The Reference Frame: Speed of light is variable: only in junk media

If you open Google Science News at this very moment, the #1 story is saying things like

new research shows that the speed of light is variable in real space.

The only problem is that the "research" is pure crackpottery. Those stories build upon the following two papers in a journal called European Physical Journal D I have never heard of in the context of fundamental physics:

A sum rule for charged elementary particles by Gerd Leuchs, Luis L. S?nchez-Soto (free: arXiv)

---

The quantum vacuum as the origin of the speed of light by Marcel Urban, Fran?ois Couchot, Xavier Sarazin, Arache Djannati-Atai (free: arXiv)

The abstracts are enough to see that the authors aren't just making one or two serious technical errors. Instead, they misunderstand the very logic of science - how arguments in favor of some claims may or may not be phrased.

The first, German-Spanish paper tries to claim that the sum of squared electric charges over all elementary particle species (regardless of their mass) is \[

\sum_i Q_i^2 \sim 100.

\] This is quite a bold statement. You may try to look what is the quantum field theoretical (or stringy?) calculation leading to this condition. What you will find is that there isn't any quantum field theory in the paper at all!

Instead, the paper misinterprets virtual particles etc. in the way you expect from a 10-year-old schoolkid. For them, the virtual particles are real and they're connected by springs of some sort. Some physically meaningless calculations lead them to the sum of the squared charges. If you try to find out where the number \(100\) came from, you will find out that it was calculated as a function of three more real parameters whose values were chosen arbitrarily.

It would be a terribly stupid paper even for a 10-year-old boy. But the authors must believe that it's possible to learn things about physics in this way even if they don't know anything about the way how modern physics describes particle species and their interactions with the electromagnetic field ? about quantum field theory. So one sentence in the paper refers to quantum field theory, after all. It's the last sentence before acknowledgements that says:

We hope that this result will stimulate more rigorous quantum ?eld theoretical calculations.

Wow: they leave the details for their assistants whose task is to convert the ingenious findings that contradict everything that a quantum field theory could say about these matters to a proof in quantum field theory.

Needless to say, it's totally impossible in \(d=4\) to have a similar constraint for the sum of squared charges. At most, the sum of cubed charges is what enters the gauge anomalies in \(d=4\). But summed squared charges over particle species can't occur in physically meaningless formulae. Moreover, the number of particle species is really infinite ? although most of them may have masses near the string scale or higher ? so the sum is either ill-defined or divergent. In other words, it's implausible for an important physical formula to deal with particle species regardless of their mass.

Via Gene, off-topic: Lots of music for a buck.

The other paper, the French one, is a similar nonsense about the variable speed of light. These papers are being clumped together because the authors of both of them are clearly pals and they coordinated their invasion into the journals and the media. Let me repost the abstract here:

We show that the vacuum permeability and permittivity may originate from the magnetization and the polarization of continuously appearing and disappearing fermion pairs. We then show that if we simply model the propagation of the photon in vacuum as a series of transient captures within these ephemeral pairs, we can derive a finite photon velocity. Requiring that this velocity is equal to the speed of light constrains our model of vacuum. Within this approach, the propagation of a photon is a statistical process at scales much larger than the Planck scale. Therefore we expect its time of flight to fluctuate. We propose an experimental test of this prediction.

Unbelievable. Look at the first sentence. They think that they "show" that the vacuum permeability and permittivity "may" originate from the magnetization and the polarization of continuously appearing and disappearing fermion pairs. (Needless to say, there's no quantum field theory in this paper, either.) How do they achieve this ambitious task?

It's easy. They forget and ignore everything we know about physics and everything they should have learned about physics, even at the high school. In this state of perfect oblivion, one isn't constrained by any knowledge at all ? because there isn't any knowledge ? so anything goes and an arbitrarily stupid pile of crackpottery "may" be true and one thus "shows" that it's possible.

Except that a person who knows something about physics may show that pretty much every sentence in this paper is pure rubbish. Their particular nonsense that "may" be true as they "show" is that the vacuum is chaotic for photons so the light propagation is chaotic and the speed is variable. By saying these things, they prove that they don't have the slightest clue about the actual explanation of the existence of light that we have known since the late 19th century.

The actual explanation of light is that it's a type of electromagnetic waves. And electromagnetic waves are simple solutions to Maxwell's equations, the equations that describe all electromagnetic phenomena. These equations are particularly simple in the vacuum. Maxwell's equations in the vacuum are actually the more fundamental ones; the propagation of electromagnetic waves in other mediums requires some extra work.

But in the vacuum, the permittivity \(\varepsilon_0\) and permeability \(\mu_0\) simply enter Maxwell's equations as conversion factors that disappear ? that are replaced by \(1\) ? if we use more natural units. The reason why I say these things is that \(\mu_0,\varepsilon_0\) are not supposed to be "derived" from any complicated mechanism involving lots of charged particles etc. On the contrary, they're players in the most fundamental equations of electromagnetism and it's the behavior of lots of charged particles that is "derived" and that can be reduced to fundamental Maxwell's equations.

Hendrik Lorentz was the first man who showed that Maxwell's equations in general materials may be derived from the vacuum Maxwell's equations combined with some behavior of the charged and magnetized particles that exist inside the materials. It was an important insight (it helped Einstein to think in the right way when he was marching towards relativity) and people could have been unfamiliar with this insight at some point ? except that Lorentz found those things more than 100 years ago so they shouldn't be unknown to authors of a journal called European Physical Journal D in 2013.

The authors are trying to derive the light propagation in the vacuum from light propagation in some fictitious complex material ? which is exactly the opposite strategy than physics chooses (and it's obvious why it chooses the opposite one): complicated materials are more complicated than the vacuum. In other words, the authors suggest that if their contrived "additional" effects didn't exist, the permittivity and permeability would vanish in the vacuum. But they couldn't vanish. Even when all the chaos is removed, physics must be described by non-singular equations which essentially means ? among many other things ? that the permittivity and permeability would still have to be finite nonzero constant in the vacuum. We know what these constants are: they are \(\varepsilon_0,\mu_0\).

But what is even more important is that the authors don't understand what is primary in science: unrestricted speculations about the ways how the world "may" work, or constraints from observations and experiments? They clearly think that it's the former. They "may" write kilobytes about nonsensical models that have nothing whatsoever to do with the Universe around us and they claim that this "shows" something.

But science doesn't work like that. We actually know that the speed of light has to be completely constant and free of any fundamental "noise". In fact, our definition of one meter is such that the speed of light in the vacuum is tautologically \(299,792,458\,{\rm m/s}\). So it's obviously constant. The constancy of the vacuum speed of light follows directly from special relativity and special relativity is what we actually know to be true from the observations. So all the speculations must adjust to this knowledge ? and all other empirical knowledge we have. The authors' approach is just the opposite: they want the empirical knowledge to be adjusted to their unconstrained fantasies. They simply don't understand the basic point of science that the self-consistency of a hypothesis isn't enough for such a hypothesis to be a good scientific theory. Empirical knowledge actually matters and kills most of the conceivable guesses.

I can't resist to compare their approach with the following question that a user named John Smith asked on Physics Stack Exchange two days ago:

Why perpetual motion wouldn't be possible if we are so technological advanced?

You see some kind of a fundamental misunderstanding about the inner workings of the Universe and the humanity. John Smith ? and similarly the authors of the papers discussed in this blog entry ? doesn't get the point that regardless of the technological sophistication, every civilization much like every object in Nature is "obliged" to obey the laws of physics and the non-existence of the perpetual motion machines are among these laws (the so-called first two laws of thermodynamics).

John Smith's ? and the authors' ? opinion about this basic issue (about the very existence of the laws of Nature) is the opposite one. He believes ? and they believe ? that there are no permanent laws, there are just limitations that we're constantly breaking as we're getting more technologically advanced and more self-confident. The non-existence of the perpetual motion machines (or similarly the constancy of the speed of light in the vacuum) must be just due to some limitations of technology we can surely transcend in 2013 if we want! ;-)

It doesn't make sense to spend too much time with these silly papers. So I will stop and finish this blog entry with the complaint that the adjective European in the name of the journal could be replaced by Idiots' if we wanted the name of the journal to be more accurate. And that's not a good result for the old continent of ours! At the same moment, these idiotic crackpot papers are widely quoted in the U.S. and other media so Europe is not the unique continent on which similar junk flourishes.

And that's the memo.

Source: http://motls.blogspot.com/2013/03/speed-of-light-is-variable-only-in-junk.html

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