Help with debunking pseudoscience physics claim I read this paper (PHYSIQUE MICRO-VIBRATOIRE ET FORCES INVISIBLES par A. de BELIZAL et P. A. MOREL) that claims that purely magnetic gamma rays exist. They call them negative green. They show pictures, like the one attached here,

claiming to have captured images of gamma rays on photographic film (not clear if the picture is a print or a negative) but they also say that they couldn't detect any gamma rays using a geiger counter. So they hypothesize that they discovered a new type of energy that is mostly magnetic. This seems to completely defy the laws of physics.
Can anyone help me to debunk this claim?
 A: Magnetic radiation (by which I assume you mean oscillations in the magnetic field) by itself cannot propagate without producing tandem oscillations in the electric field, by Ampere's and Faraday's laws. Moreover, a "purely" magnetic field vector can be transformed partially into an electric field vector by  the observer boosting to a different reference frame, per special relativity.
So you cannot have a wave purely in the magnetic field. It would be somewhat akin to trying to have an acoustic wave with only crests and no troughs.
A: I found a copy of the paper here. It is from 1976.  My French is weak, but on page 16 or so they divide electromagnetic waves into

Il y a sept vibrations-couleurs visibles avec chacune ses infra et ses ultra, a savoir :
Violet; Indigo; Bleu; Vert positif ou vert du spectre visible; Jaune; Orangé; Rouge,
Puis cinq vibrations-couleurs invisibles avec également chacune leurs infra et leurs ultra, soit ;
Infra-Rouge ; Noir; Vert négatif; Blanc; Ultra-violet.

You can probably stop reading there: “noir (black)” and “blanc (white)” are not parts of the electromagnetic spectrum, so “negative green” almost certainly isn’t either.
A few pages later they arrange these twelve “colors” in a ring, so that negative-green is opposite positive-green on the invisible side.  There’s just nothing there.  “Not even wrong,” in the jargon of debunkers.
I have no idea what’s happening in that photo, but I expect the effort-to-payoff ratio for figuring it it out would not be very good.
