But it is not altogether satisfactory to contemplate a material that is inactive magnetically. ... And in general—what is the relation between any material and the character or power we may attribute to it?
Can there, in fact, be a “true zero” in the sense of inactivity? “Neutral” media clearly sustain some sort of magnetic relations—for they transmit magnetic forces. We cannot, therefore, view nitrogen and other “truly” neutral materials as simply devoid of magnetic power. But then—must it not follow?—if neutral materials are magnetically active we must equally attribute magnetic activity to space!
Faraday cannot escape this unwelcome consequence. Nevertheless it seems incomprehensible to him that an absence of matter can act in relation to magnetism. Although he acknowledges the fact that space can sustain a magnetic condition, he refuses to accept the equivalence of matter and space, which that fact would seem to imply:
Before determining the place of zero amongst magnetic and diamagnetic bodies, we have to consider the true character and relation of space free from any material substance. Though one cannot procure a space perfectly free from matter, one can make a close approximation to it in a carefully prepared Torricellian vacuum. Perhaps it is hardly necessary for me to state, that I find both iron and bismuth in such vacua perfectly obedient to the magnet. From such experiments, and also from general observations and knowledge, it seems manifest that the lines of magnetic force can traverse pure space, just as gravitating force does, and as static electrical forces do; and therefore space has a magnetic relation of its own, and one that we shall probably find hereafter to be of the utmost importance in natural phenomena. But this character of space is not of the same kind as that which, in relation to matter, we endeavour to express by the terms magnetic and diamagnetic. To confuse them together would be to confound space with matter, and to trouble all the conceptions by which we endeavour to understand and work out a progressively clearer view of the mode of action and the laws of natural forces. It would be as if in gravitation or electrical forces, one were to confound the particles acting on each other with the space across which they are acting, and would, I think, shut the door to advancement. Mere space cannot act as matter acts. ...
Here for almost the only time in the Experimental Researches, Faraday’s writing takes on a doctrinaire tone. Though compelled to acknowledge that space has a magnetic condition, he resolutely maintains that it cannot be the same kind of condition that matter has. His pronouncement that “mere space cannot act as matter acts” seems but a retreat into verbal orthodoxy. Why is he so insistent upon the separation of matter and space?
Howard J. Fisher
Michael Faraday Wiki Page