http://www.instructables.com/id/Faraday-Rotation-EPIC/

You are right that Faraday himself couldn’t observe the effect in air. As he himself writes, though,

…I am inclined to believe that even air and gases have the power to assume the peculiar state, and even to affect light, but in a degree so small that as yet it has not been made sensible. Still the gaseous state is such a remarkable condition of matter, that we ought not too hastily to assume that the substances which, in the solid and liquid state, possess properties even general in character, always carry these into their gaseous condition

It seems that air should have the effect, but it is too weak to observe with Faraday’s apparatus. The fact that one can see Faraday rotation even for waves propagating in the almost-matter-free interstellar space suggests that air would have a similar effect. (Though, like Faraday, I can’t rule out something ‘weird’ happening due to collisional effects.)

Many blogs are merely reactions to current events, or statements of opinion. But here we have an original work of pedagogy, and I have to say it’s welcome.

As to the substance of the post, I do have a question. It sounds like Faraday and his contemporaries observed the rotation effect when dielectric solids and even liquids were placed in the magnetic field, but not when the field passed through the air alone.

But air is a dielectric too — is it just that the effect is weaker due to air’s much lower density, so it’s not detectable in a small experimental apparatus? Or perhaps the fast random motion of the air molecules is at fault?

What physics postulates are falsifiable without contradicting prior observation? If spacetime were an EP-violating, anisotropic vacuum and conservation of angular momentum-violating (Noether’s theorem), Lorentz invariance-violating, *massed sector* left foot… then what? Massless EM is irrelevant. Socks are inert to left feet as are left shoes. Right shoes fit differently and are diagnostic. Get a right shoe and look.

Atoms can self-similarly stack 230 ways in 3-space, the crystallographic space groups. 65 of those contain chiral mass distributions. 11 pairs in the 65 are themselves chiral – even identical single atoms so arranged are a chiral mass distribution (e.g., tellurium). Delete space group pairs containing racemic and conflicting screw axes. P3(1)21 and P3(2)21 persist: Left- and right-handed alpha-quartz, commercially grown to kilogram single crystals.

All contrasted chemical compositions validate the Equivalence Principle to at least one part in 20 trillion difference/average in the lab (Eotvos experiment. Neutron stars in binary systems concur.) Test spacetime geometry not with composition but with geometry: Do opposed P3(1)21 and P3(2)21 single crystal quartz test masses fall differently?

http://www.npl.washington.edu/eotwash/experiments/equivalencePrinciple/epWhat.html
Eotvos vertical torsion balance

Of course they validate the EP; there’s no need to look! But there is. That is why Faraday is celebrated as the premier empiricist, why Yang and Lee went from nobodies to Sweden in under a year. Discovery simply is. Theory is rewritten without apology or regret to accommodate it. Massed sector parity violation is an Achilles heel of physics, denied and decried because it is chemistry (but consistent with prior observation both ways). Faraday would look.

Academic and industrial funding enthusastically embraces theory to the exclusion of heterodox observation. A broad swath of adapted physics evolved credit default swaps, collateralized debt obligations, structured investment vehicles, and mortgage backed securities. How did that turn out when the universe voted?

As for Bell Labs, several breakthrough discoveries that led to revolutionary technologies were discovered there before the advent of Lucent. The impressive number Nobel prize winners from Bell Labs are a testament to these facts. Moreover, the takeover from Lucent should not be seen as stemming from mismanagement or unfocused scientific research. Rather it should be seen as a direct consequence of today’s economic dynamics. Currently, companies are asked to provide short term benefits with all the metrics that you mentioned to assess the risks involved. Many types of discoveries that were unravelled by Bell Labs are either long-term based or difficult to assess the risks, and so do not fit well this new kind of highly competitive environment. Nowadays, discoveries that need long-term investment and dedication are almost solely filled via academic institutions.

This is the irresponsible, wasteful, intolerable randomness that doomed Bell Labs. After Lucent took over Bell Labs’ noses were applied to the grindstone. Budgets were impressed, PERT charts were drawn, DCF/ROI metrics were established. Personnel were hired supportive of Corporate Culture. Subsequent performance analyses indicated R&D programs were more vigorous and more tightly focused. Bell Labs rapidly transformed into a one time write-down, cost against revenues, generating a welcomed pulse of net retained earnings against taxation.

As this is being written the Dow-Jones has moved 230 points. That is the power of professional management thwarting workers’ insubordination and optimizing internal corporate dynamics.

(All compositions of matter vacuum free fall identically – the postulated Equivalence Principle. Do chemically identical left and right shoes violate the EP? Eotvos balances are funded. Left- and right-handed single crystal quartz is commercially grown. Nobody should look!)