Last spring it dawned on Apple CEO Steve Jobs that the heart of his hit iPod digital music player was the "shuffle." This feature allows users to mix up their entire song collections—thousands of tunes—and play them back in a jumbled order, like a private radio station. Jobs not only moved the popular shuffle option to an exalted place on the top menu of the iPod, he also used the idea as the design principle of the new low-cost iPod Shuffle. Its ad slogan celebrates the serendipity music lovers embrace when their songs are reordered by chance—"Life is random."
But just about everyone who has an iPod has wondered how random the iPod shuffle function really is. From the day I loaded up my first Pod, it was as if the little devil liked to play favorites. It had a particular fondness for Steely Dan, whose songs always seemed to pop up two or three times in the first hour of play. Other songs seemed to be exiled to a forgotten corner of the disk drive. Months after I bought "Wild Thing" from the iTunes store, I'm still waiting for my iPod to cue it up.
More than a year ago, I outlined these concerns to Jobs; he dialed up an engineer who insisted that shuffle played no favorites. Since then, however, millions of new Podders have started shuffling, and the question has been discussed in newspapers, blogs and countless conversations. It's taking on Oliver Stone-like conspiracy buzz.
Apple execs profess amusement. "It's part of the magic of shuffle," says Greg Joswiak, the VP for iPod products. Still, I asked him last week to double-check with the engineers. They flatly assured him that "Random is random," and the algorithm that does the shuffling has been tested and reverified.
More specifically, when an iPod does a shuffle, it reorders the songs much the way a Vegas dealer shuffles a deck of cards, then plays them back in the new order. So if you keep listening for the week or so it takes to complete the list, you will hear everything, just once. But people generally listen only to the first few dozen songs. In theory, that sample should be evenly distributed among all the artists and albums in their collections. So why do you typically get three Wilco songs in an hour while Aretha Franklin waits in the wings forever?
The question will be even more important to owners of the new tiny iPod Shuffles. These use a new feature called autofill to load the one-ounce players with a supposedly random selection of 120 or so songs from much larger collections. The first few times I tried this, I found some disturbing clusters in the songs chosen. More than once the "random" playlist included three tracks from the same album! Since there are more than 3,000 tunes in my library, this seemed to defy the odds.
Or did it? I explained this phenomenon to Temple University prof John Allen Paulos, an expert in applying mathematical theory to everyday life. His conclusion: it's entirely possible that nothing at all is amiss with the shuffle function. It's quite common for random processes (like coin tosses) to get unlikely results here and there, like runs of six heads in a row. Over a very long time, it evens out, but it's hard for us to envision that. "We often interpret and impose patterns on random processes," he says, adding that this might be expected in the case of music, which evokes strong emotions. Paul Kocher, president of Cryptography Research, puts it another way: "Our brains aren't wired to understand randomness."
Life may indeed be random, and the iPod probably is, too. But we humans will always provide our own narratives and patterns to bring chaos under control. The fault, if there is any, lies not in shuffle but in ourselves.
On the other hand, I'm still waiting for "Wild Thing."