IT'S AN EXTRAORDINARY SIGHT - a magnetic top spinning, bobbing and weaving in space for two minutes or longer. It remains levitated two or three inches above a larger base magnet. The top is not touching any other object, and no strings, electricity or other devices are used.
|A levitating magnet (Photo by Rod Driver)|
Levitation is one of mankind's oldest dreams, and it has now been achieved using just a few dollars' worth of ordinary permanent magnets and some pieces of plastic.
Anyone with even a casual interest in physics has to be amazed. For more than 150 years such levitation was "known" to be impossible. An 1842 paper by Rev. Samuel Earnshaw in an English scientific journal had effectively proved mathematically that stationary levitation will never be achieved using only ordinary permanent magnets. "Earnshaw's theorem" is stated in many college textbooks on electricity and magnetism. But this hasn't stopped thousands of people (including yours truly) from spending countless futile hours trying to achieve such levitation anyway. (Earnshaw's theorem does not deny the possibility of levitation using "diamagnetic" materials, superconductors or active electromagnetic circuits. The big surprise is the achievement of levitation using just ordinary permanent magnets.)
When I first saw a levitating magnet in a store in 1994 I had to have one -- and I didn't mean tomorrow! No scientist had even suggested, let alone proved, that a spinning magnet could levitate in apparent defiance of Earnshaw's theorem. And even after seeing it done, it is not trivial to reproduce it. The toy comes with a set of brass and plastic washers to adjust the weight of the spinning magnet. The weight must be experimentally adjusted to within one-tenth of a gram - less than the weight of a single postage stamp. Also the base magnet must be carefully leveled. The top will not levitate unless the weight is right, and you cannot be sure the weight is right until the top levitates. Moreover you cannot even begin to adjust the weight and leveling until you have learned how to spin the magnetic top while fighting the strong resisting force of the base magnet. It was remarkable that someone had made the idea work initially -- without knowing that it was possible.
So I promptly contacted the physicists who had patented the invention, Bill Hones in Seattle and his father Ed Hones in Los Alamos, N.M. But despite spending at total of 50 minutes on the phone with these two gentlemen, I never really got an answer to the question, "How did you first do it?" The best I could gather was that they had had faith in their dream that it could be done plus an extraordinary amount of patience and determination.
For four years I showed this remarkable toy to anyone who exhibited the slightest interest -- plus many who didn't - expressing my admiration for Bill and Ed Hones for their remarkable discovery.
Meanwhile in New Mexico, a couple named Mike and Karen Sherlock had been so excited when they first saw a levitating magnet that they had established a mail-order business devoted exclusively to selling these amazing toys. Knowing the difficulty that a newcomer encounters when first trying to make the device work, the Sherlocks also produced an instructional video featuring "the inventor" Bill Hones. As a result of their advertising on the radio and on the internet, the Sherlocks were soon selling hundreds per day, each shipped with a copy of the video.
It was only after the fact - after this levitation phenomenon became known -- that several physicists wrote papers to explain it. There is still more work to be done on this. A complete proof that such sustained levitation is possible appears to be a difficult mathematical challenge.
But there was something else of interest in the published papers. Several of the authors remarked that Bill and Ed Hones were really not the inventors - Bill Hones had allegedly learned how to levitate a magnet from a man in Vermont named Roy Harrigan who had patented his "Levitation Device" in 1983.
When Mike and Karen Sherlock heard and confirmed this story in 1997, they were shocked; they stopped selling the toy and they reported the reasons on their Web site.
Wanting to meet the inventor said to be responsible for the amazing scientific discovery, my wife and I visited Roy Harrigan in March. Harrigan and his wife live in an isolated house on a hill near Manchester, Vermont. When we got there the driveway was under 18 inches of snow. Harrigan would rather invent than shovel.
The only place to sit in Harrigan's living room is the couch. Every other chair, the table, the desk plus much of the floor is covered with magnets, motors, a radiometer, a spark coil, a van de Graff generator, various Harrigan inventions, ideas and drawings plus other devices under construction.
Harrigan, 57, is a high-school graduate who also spent an unsatisfying year and a half in college. He said he has thousands of inventions, and he showed us several. Sixteen patents are registered in his name. He doesn't have the money to patent them all, he said. None has brought him either fame or fortune.
To me, Roy Harrigan's most exciting device was the levitating magnet; although he does not consider it his most important invention. He had attempted magnetic levitation as a child. Then more than 20 years ago he got the idea of spinning the smaller magnet. Experts assured him that such levitation was impossible. But Harrigan didn't know Earnshaw's theorem. So he just kept trying until one day, after perhaps a thousand attempts, the magnet floated in space. After seven years of hassles, Harrigan was granted US patent No. 4,382,245 for the invention in May 1983.
But Harrigan had had bad experiences with purported backers of earlier inventions; and he had become suspicious of anyone who claimed to be helping him. This soon became true for the magnetic invention also. So he did not market it; and his patent remained unnoticed. Any scientist or engineer who might have run across it probably assumed that the idea would not work. It wouldn't have been the first patent awarded for an idea that doesn't work.
Tomorrow: A patent that fails to protect.
Rod Driver, an occassional contributor, is a professor of mathematics at the University of Rhode island and a former state representative.