Historical research guide · 0597 · 1972

Photon Mass and New Experimental Results on Longitudinal Displacements of Laser Beams near Total Reflection

Louis de Broglie · Jean Pierre Vigier

In one minute

Louis de Broglie and Jean-Pierre Vigier take a small optical anomaly and read a large conclusion out of it. When a light beam strikes a surface from inside at the total-reflection angle, it does not simply turn around at the boundary: it slides a short way along the surface first, then leaves. That slide is the Goos-Hänchen displacement, and Christian Imbert had just measured it with a laser more carefully than anyone before him. His numbers did not match what classical electromagnetism or standard quantum optics predict for linearly polarised incident plane waves. De Broglie, then eighty, and Vigier propose a reading of the mismatch: treat the reflection as a Stern-Gerlach measurement — the kind that splits a beam by spin — performed on the photon’s own spin. On that reading the observations come out simply. The condition is the interesting part. The interpretation works only if the photon carries a small non-zero rest mass, which is de Broglie’s lifelong proposal brought down to a laboratory bench.

Connection

Chapter 10 rests on the electromagnetic potentials being physical quantities rather than bookkeeping, and a photon rest mass is the sharpest version of that claim: give the photon mass and the vector potential enters the field equations directly, with a value that matters. Chapter 13 is where such threads join, and this Letter is the moment the question stops being cosmological and becomes something a bench-top optics experiment can speak to.

From the source

Christian Imbert’s laser measurements of the longitudinal displacement of a beam reflected near the total-reflection angle contradict both the classical and the quantum predictions for linearly polarised incident plane waves. The disagreement is with the standard treatment of the Goos-Hänchen effect, not with the effect’s existence.Abstract, first sentence
Those observations can be simply interpreted as a Stern-Gerlach type of measurement of the photon spin — the reflecting boundary acting on the beam the way an inhomogeneous magnetic field acts on a beam of atoms.Abstract, second sentence
That interpretation carries one condition: the photon must have a non-zero rest mass. De Broglie and Vigier put the requirement in the title rather than burying it, so the optical result and the mass hypothesis stand or fall together.Title; Abstract, second sentence
Reading the reflection as a spin measurement makes the displacement depend on the polarisation state of the incident light, which is what turns the experiment into a test rather than an anomaly: change the polarisation and the predicted slide changes with it.Abstract, second sentence
The paper puts photon rest mass where de Broglie always argued it belonged — among the quantities an experiment measures rather than the ones a theory assumes to be zero. A table-top optical measurement, not only an astronomical bound, is treated as capable of bearing on it.Title and abstract taken together

The way in

https://doi.org/10.1103/PhysRevLett.28.1001

Historical source-access record. This guide links to the original; it does not reproduce the paper text.

AUTHORSHIP CHECKED. The dispatch note for this sheet described it as a Monstein and Wesley paper on longitudinal displacement currents. That is a different work. The digital object identifier, the Crossref record and the OpenAlex record all resolve to Louis de Broglie and Jean-Pierre Vigier, Physical Review Letters 28, 1001, published 3 April 1972, and the sheet is written to that paper. The registry entry lists the person as Jean-Pierre Vigier (archive) with de Broglie missing from the creators; the frontmatter here carries both authors. LICENCE. The paper is closed at the publisher under the APS default licence and has no repository copy, so none of its text is reproduced. The summary and claims were written from the authors’ own published abstract, read in full from the publisher record; page and section locators are not available for a closed two-page Letter, so the locators name the abstract. The modern spacecraft bound on the same quantity is on this site at /library/stm-3f9f01eaa2, and the scalar-wave reading of the potentials at /library/stm-a5e9c61635.

How to cite it

Louis de Broglie, Jean Pierre Vigier (1972) Photon Mass and New Experimental Results on Longitudinal Displacements of Laser Beams near Total Reflection doi:10.1103/PhysRevLett.28.1001

Where it sits in the curriculum

Scalar waves and the field behind the fields