It does if you like smaller, higher-capacity hard drives. But the road from landmark paper to an iPod often is longer than we like to think. Such is the case of Albert Fert (Université Paris-Sud, Orsay, France) and Peter Grünberg (Forschungszentrum Jülich, Germany), who just won the 2007 Nobel Prize in physics for a discovery that makes micro hard drives possible.

In 1988 — when 60,000 computers comprised the Internet, and the World Wide Web lay 7 years away — the prize-winning scientists independently discovered a new physical effect, called Giant Magnetoresistance (GMR). What they found was a dramatic (this is the “giant” part of GMR) change in the electrical resistance of multilayer thin films when they applied a magnetic field to them (the “magnetoresistance” part).

The external magnetic field changes how magnetic regions in some of the film’s layers orient themselves. When the fields in adjacent layers align, electrons with spins parallel to the fields (so-called spin-up electrons) pass easily from one layer to another, while electrons with opposing spin (down) scatter strongly. This means spin-up electrons can flow easily and there’s low resistance. On the other hand, if fields in adjacent regions point in opposite directions, then both up and down electrons strongly scatter and there’s high resistance to current flow. Here’s a cool Flash animation to help you picture GMR in action.

Very well, you say, but what does it mean to me? The incredible shrinking hard drives of recent years simply wouldn’t be possible without GMR. No 60-gigabyte iPod Photo for you — at least, not without a backpack.

A new style of non-volatile (your data doesn’t disappear when you turn it off) computer memory is another offshoot. But what really turns on technology mavens is the promise of computing by manipulating an electron’s spin, rather than its charge. This emergent field, called “spintronics,” so far has its most successful offspring in GMR devices.