No, this isn’t a column about the magnets you buy for your shoes, knee braces, or whatnot – the magnets that supposedly can cure all manner of ills. Rather, it’s a paean to one of the 19th century’s most miraculous discoveries, a discovery without which modern life would be indescribably different.
Many of us, at some point or other, have wrapped a piece of coated wire around a nail and hooked the wire up to a battery. That is a quick way to make an electromagnet. (Certain kinds of nails work better than others; more about that in a post to come.) Such on-demand magnets are integral parts of electric motors; really big ones are used in junkyards to lift scrap metal by the ton.
Ultimately, a magnetic field is created whenever electrically charged objects move around and around in circles. That’s what makes electromagnets work. Indeed, that’s what makes all magnets work – even the ones that stick to your refrigerator door have tiny currents flowing within them, currents that exist because individual electrons are spinning inside those magnets like whirling dervishes.
Just as moving electrons can create magnetic fields, the opposite holds as well: moving magnets can make current flow. British physicist Michael Faraday established this in the 1830s by moving a magnet through a coiled wire. Two centuries later, all but a tiny percentage of household current relies on magnets zooming alongside wire coils. It doesn’t matter whether the movement is powered by radioactive atoms, cascading water, roaring winds, or flaming coal.
It's easy to envy Mr. Faraday. What good fortune to grow up in a time when the simplest physics experiments could break new ground, a time when, on the strength of his character and conviction, a humble bookbinder could apprentice himself to the scientific greats of his time (so that in time he could become one of them). Today, it seems, progress rests on multibillion-dollar behemoths like the Large Hadron Collider or the Hubble Space Telescope.
And yet we still can read stories like that of Jason Cox, a Marine sergeant who developed a new sensor for roadside bombs, and David Neal, an NBC production supervisor who invented a gravity-powered camera to track Olympic athletes on their graceful arcs from diving board to swimming pool.
It's also worth remembering that Faraday labored in a world where slavery was legal and widespread in much of the so-called civilized world; a world where women were almost entirely excluded from realms of study and power; a world where humans rich and poor often died from circumstances that now are avoided in all but the most desperate corners of the globe. The tale of human progress is a checkered saga, one in which genius and genocide incomprehensibly coexist.
The Disappearing Penny
If you took me up on the suggestion made in my previous post, you may have seen a penny disappear when water was poured into a glass vessel though which you gazed at the penny from the side. You may then have seen the penny reappear when the penny and the vessel themselves were immersed in the same liquid. Have you formulated any theories to account for this behavior? If so, how might you test them?
Copyright 2009 Joshua Roth.