My wireless woes continued today, although with some marginal improvement: wireless service was available, it was just a bit slow and prone to cutting out altogether on occasion -- often just when I needed to save a blog post. I only bring it up because the unquestioned highlight of this afternoon's Frontiers in Physics session was a talk by MIT's Marin Soljacic on his proposed scheme for wireless non-radiative energy transfer. I expect it'll be on all the science news feeds by tomorrow morning, having generated quite a bit of excitement in the news media and scientific community alike.

It's still in the theoretical stages -- experimental verification is underway -- but if Soljacic's strategy turns out to be feasible, it might one day be possible to recharge our laptop computers, cell phones, and other indispensable electronic gadgets wirelessly, without having to lug around so many different kinds of chargers. (As someone whose cell phone died just two days ago as a result of charger failure, that day can't come soon enough.)

The critical word here is "non-radiative" -- that is, without the usual massive energy losses. Physicists know it's possible to transmit energy wirelessly, but over long distances, the waves dissipate too quickly for efficient transfer. That's the part that caused colleagues of session moderator M.T. Bernius (Dow Chemical) to email him exclaiming, "This is impossible! How can this be?!?" To his credit, Bernius respected the media embargo and declined to spill the beans. I won't go into excessive technical detail here; the work is described in a readily available preprint on arXiv, for those wishing more extensive detail. Suffice to say, it's an interesting idea with some practical potential applications. AIP will also be posting all the PowerPoint slides from the two days of presentations, including that of Soljacic, some time next week.

Soljacic says he got the idea from what has become a common item: a cell phone. His wife kept forgetting to recharge her Nokia cell phone, whose battery would emit a loud noise whenever it was running low -- often happening late at night or in the wee hours of the morning. Soljacic thought it might be nice if the cell phone could recharge itself, but to do so, one would need to transfer energy wirelessly with minimal energy loss.

He's not the first to think of it, as he readily admits. Famed 19th century Serbian inventor Nikola Tesla began constructing a giant radio station in Wardenclyffe, New York in 1901, financed by J.P. Morgan. It stood 187 feet high, capped by a 68-foot dome, and was supposed to be able to transmit radio signals without wires to any point of the globe. Tesla wasn't afraid to think big. Alas, the tower was never completed, because Tesla fell out with Morgan when the project ran way over budget and took much longer to build than originally anticipated. Wardenclyffe was razed in 1915 and its parts sold as scrap metal.

It looks like Soljacic's concept will fare quite a bit better. His insight is that the close-range induction that happens inside your basic transformer could potentially transfer energy over longer (short and mid-range) distances -- say, from one end of a room to the other A power transmitter would fill the space with a "non-radiative" EM field, and the energy would only be detected by gadgets designed to "resonate" with that field. Most of the energy not picked up by a receiver would be reabsorbed by the emitter.

Soljacic has a gift for memorable imagery: he held up one of his shoes by the laces during his presentation to demonstrate an object's response to excitation at just the right resonant frequency. He's also a big fan of Roomba, the popular robotic vacuum cleaner, and envisions a day when wireless energy could power not just industrial applications or electric vehicles (including helicopters!), but also freely roaming nanorobots, or macroscale robotic factory workers.

There were some obvious constraints to the basic idea, including available materials, extraneous environmental objects, and the like, but Soljacic and his colleagues played around with a few prototyoe designs and found a couple that would have limited range, but still performed well-enough at mid-range distances to conceivable rexharge a laptop or cellphone a few meters from the power source.

Of course, the basic underlying physics of Soljacic's scheme has been known for 200 years -- it's all about manipulating the physics of electromagnetic fields -- so why did it take so long for a scientist to think of doing this? Soljacic pointed out that new technologies usually emerge under two types of circumstances: when new physics is discovered that enables new applications or offers significant improvements to existing applications; and when society is finally ready to accept the new technologies. He thinks nonradiative wireless energy transfer falls into the latter category, since its development was dependent on the proliferation of cell phones, wireless Internet and other advances that have become essential aspects of modern life -- but only in the last 10 years or so.

Tesla, as always, was a man far, far ahead of his time. I'm rooting for Soljacic's scheme if only to confer some belated validation of Tesla's visionary genius 100 years ago.