a gift that keeps on giving

I've always had a soft spot for Michael Faraday, for any number of reasons, but one of those reasons is that he was a brilliant experimentalist with world-class instincts for investigating the behavior of this strange new phenomenon, and yet he possessed only rudimentary mathematical skills -- something that hampered the broad acceptance of his concept of how electromagnetism worked.

And then there was his inveterate bookishness. He came from working class origins: he was the son of an English blacksmith, apprenticed to a bookbinder at 14. Some might have considered this a sucky job, but the young Faraday took advantage of access to all that knowledge, and read voraciously (I was one of those kids who started reading very early, and would compulsively read a cereal box if that's all that was available to me).

Faraday was especially fond of reading about the natural sciences. Serendipitously, as his apprenticeship was ending, a friend gave him a ticket to a lecture  on electrochemistry by the eminent scientist Humphrey Davey, at the Royal Institution -- not a venue where the young humble-born Faraday would normally be welcomed. Faraday was entranced, and asked Davy for a job. There wasn't a position available, Davy gently told the young man, but shortly thereafter he sacked his assistant for brawling and hired Faraday in his stead. It has famously been said that Michael Faraday was Davy's greatest discovery; considering that Davy discovered the elements barium, strontium, sodium, potassium, calcium and magnesium, that is no mean compliment.

Not that Faraday found immediate acceptance in polite British society. He was not considered a "gentleman" by the standards of the day. In fact, when Davy and his wife toured the continent from 1813-1815, Faraday was supposed to accompany them as Davy's scientific assistant -- except when Davy's valet declined to go, too, Faraday was forced to step in, eating with the servants and traveling outside the coach. Faraday endured the poor treatment for the sake of all the stimulating ideas and European scientists he encountered along the way. But it had to rankle a bit.

Fast forward to 1820, when news reached England of an exciting new discovery by Dutch scientist Hans Christian Oersted: namely, that electricity and magnetism were not two distinct forces, but the same force: flip sides of the same coin, if you will. Oersted's famous experiment is now a staple of physics classrooms. Take a compass needle mounted on a wooden stand as a magnet and connect it to a battery with a wire. Every time the electric current is switched on, you should see the compass needle give a small jerk. Basically, a moving electric current gives rise to a magnetic field, which is detectable by the compass needle.

Faraday was enthralled by this development, and enthusiastically dove into designing his own experiments, hoping to prove that not just electricity and magnetism, but all natural forces were somehow linked -- now an accepted part of physical theory, at least with the cosmology/particle physics crowd, but definitely more of a "fringe" notion back in 1820. "Small science" was the order of the day; this was the golden age of tabletop experiments, and Faraday (like Ernest Rutherford almost a century later) was among its most eminent practitioners.

Every physics history book or essay dutifully lists Faraday's three greatest discoveries as a matter of course. First,in 1821, he figured out that electricity could be converted into mechanical motion with the judicious application of a magnetic field (electromagnetic rotation); we have electric motors today because of this effect. In 1831, after a decade of slaving away in his lab, he demonstrated that a jiggling magnet could induce an electrical current in a wire, thereby converting the energy of a changing magnetic field into an electrical current. So we owe our electric generators to Faraday's tireless experimentation.

And then there was his discovery of the magneto-optical effect, namely, how light is affected by a magnetic field. Faraday suspected (correctly) that electricity, magnetism and light were all connected, and he concocted an experiment with polarized light to test this hypothesis. The polarization was key: normally light vibrates in all directions at once, but if you pass it through some sort of filter -- a lens, or, in Faraday's case, a piece of heavy leaded glass mounted on a magnet's poles -- the light will vibrate in a single direction.

Faraday found that if he turned on an electromagnetic, it would rotate slightly the polarization of the light, proving there was some sort of connection. He didn't have the math to prove it theoretically, but James Clerk Maxwell did, and Maxwell's equations of electromagnetism are now a staple of introductory physics classes worldwide. There's a reason light is synonymous with electromagnetic radiation among modern scientists.

My personal favorite Faraday-related experiment is called a Faraday cage (also known as a Faraday shield), an enclosure specifically designed to exclude electromagnetic fields. Faraday built the first one in 1836 to demonstrate his assertion that the charge on a charged conductor travels along the exterior surface and doesn't influence anything enclosed within it. It's essentially an application of "Gauss's Law": since like charges repel each other (opposites attract), electrical charge will "migrate" to the surface of a conducting form, such as a sphere. You can see a simulation of a typical Faraday cage here.

Faraday's 19th century version was an entire room coated with metal foil; he built it himself. Then he blasted the walls with high-voltage discharges from an electrostatic generator, and used an instrument called an electroscope to prove that no charge was present inside the actual room. -- basically a hollow conductor. But the principle applies to such mundane objects as your car: if you're inside and your car and it's struck by lightning, you'd have a pretty good chance of surviving. Don't believe me? Well, Richard Hammond of the British TV series Top Gear put this hypothesis to the test; you can watch the video on YouTube here (embedding has been disabled, for some reason). Brave man, that Hammond, putting his life in the hands of physics.

Anyway, Faraday also quickly gained recognition as an excellent public speaker. People in early Victorian England were highly interested in the latest scientific discoveries of the day. (They were also just as prone to superstition, though, and Faraday was a staunch opponent to things like table-turning, seances, and mesmerism.) Fellow naturalist William Crookes described Faraday's lectures thusly: "All is a sparking stream of eloquence and experimental illustration." One of his favorite demonstrations is now a simple experiment repeated by schoolchildren everywhere. You can see magnetic field lines -- what Faraday called lines of force -- by sprinkling iron filings onto a sheet of paper held over a bar magnet. The filings align themselves within the magnetic field, so we can "see" the patten normally invisible to us.

In particular, Faraday gave a series of famous Christmas lectures each year at the Royal Institution. One of the earliest, on the chemistry and physics of flames, became a popular book: The Chemical History of a Candle.  It was a gift that Faraday gave year after year to those who showed up to receive it: the gift of wonder at the natural world that continues to surprise us, even today, with its mysterious workings. He closed his candle lectures by telling his audience,

"Indeed, all I can say to you at the end of these lectures (for we must come to an end at one time or other) is to express a wish that you may, in your generation, be fit to compare to a candle; that, in all your actions, you may justify the beauty of the taper by making your deeds honourable and effectual in the discharge of your duty to your fellow-men."

On August 25, 1867, the flame of Faraday's life was snuffed out; his (physical and mental) health had been deteriorating for a good 20 years by then. But his gifts keep on giving, all these years later. And Christmas seems a particularly apt time to honor the man.

Comments

[Peter Moore]

Faraday's Christmas Lectures at the Royal Institution continue today. Each year a guest lecturer delivers 5 hour-long lectures over a week. The lectures are broadcast on national TV in the UK.

[Hans Henrik Krohn]

A fascinating story! A small correction: Hans Christian Ørsted wasn't Dutch but Danish, and a personal friend of H.C Andersen. More at http://en.wikipedia.org/wiki/Hans_Christian_Ørsted

[FFFearlesss]

Awesome. And obviously he rocked because there's a character in LOST named after him. :-)

[John Douglas]

Faraday's demonstrations could have been done by anyone with a few bits and pieces in a shed at the bottom of the garden..and, after the event, often have been. His demonstration of converting electrical and magnetic forces into mechanical motion used the most basic possible apparatus. I sometimes wonder if, lurking in a shed or basement somewhere, another pragmatic experimenter is about to demonstrate an application of dark energy in some similar fashion; "Here it is..it works..now we have to figure out HOW!" To us, that would seem just as impossible as that little wire crackling around it's pool of mercury...
The Christmas Lectures are a staple of the festive season; went to one from school and always watch them. Prof. Laithwaite's series sticks in the mind, gyroscopes hanging at odd angles and linear motors.. inspiring stuff.

[Ms. Scarlet]

Fantastic article! The Top Gear reference makes it even better. : )

[rrusick]

The YouTube link was malformed. You gave http://www.youtube.co/watch?v=ve6XGKZxYxA ; what was needed was http://www.youtube.com/watch?v=ve6XGKZxYxA (missing the 'm' on '.com'). Maybe this was why embedding wouldn't work?

[Richard Kirk]

Another thing about the Christmas Lectures - they are still delivered just as Faraday gave them. The lectures are addressed to an intelligent and enquiring person but with no assumptions of prior knowledge and minimal mathematics. Everything - an that includes mathematical or statistical proofs - are demonstrated with a practical demonstration. To illustrate entropy, you might talk about mixing identical objects, and how it was very unlikely to spontaneously unmix them, but in the Christmas Lectures you would get a red dyed liquid and a blue dyed liquid, pick someone out of the audience, and get them to measure the temperature, mix them, then measure the temperature again. It's an unusual way of giving lectures, but very memorable, and Faraday was famous for it. Every Christmas, Michael Faraday lives again.