The part I like concerns something that's useful for alternate historians to think about:
In 2006, he performed another experiment that chilled the blood of trendologists. Trends, it suggested, aren't merely hard to predict and engineer--they occur essentially at random.
Watts wanted to find out whether the success of a hot trend was reproducible. For example, we know that Madonna became a breakout star in 1983. But if you rewound the world back to 1982, would Madonna break out again? To find out, Watts built a world populated with real live music fans picking real music, then hit rewind, over and over again. Working with two colleagues, Watts designed an online music-downloading service. They filled it with 48 songs by new, unknown, and unsigned bands. Then they recruited roughly 14,000 people to log in. Some were asked to rank the songs based on their own personal preference, without regard to what other people thought. They were picking songs purely on each song's merit. But the other participants were put into eight groups that had "social influence": Each could see how other members of the group were ranking the songs.
Watts predicted that word of mouth would take over. And sure enough, that's what happened. In the merit group, the songs were ranked mostly equitably, with a small handful of songs drifting slightly lower or higher in popularity. But in the social worlds, as participants reacted to one another's opinions, huge waves took shape. A small, elite bunch of songs became enormously popular, rising above the pack, while another cluster fell into relative obscurity.
But here's the thing: In each of the eight social worlds, the top songs--and the bottom ones--were completely different. For example, the song "Lockdown," by 52metro, was the No. 1 song in one world, yet finished 40 out of 48 in another. Nor did there seem to be any compelling correlation between merit and success. In fact, Watts explains, only about half of a song's success seemed to be due to merit. "In general, the 'best' songs never do very badly, and the 'worst' songs never do extremely well, but almost any other result is possible," he says. Why? Because the first band to snag a few thumbs-ups in the social world tended overwhelmingly to get many more. Yet who received those crucial first votes seemed to be mostly a matter of luck.
Word of mouth and social contagion made big hits bigger. But they also made success more unpredictable. (And it's worth noting, no one in the social worlds had any more influence than anyone else.) So yes, Watts figures, if you rewound the world to 1982, Madonna would likely remain a total unknown--and someone else would have slipped into her steel-tipped corset. "You cannot predict in advance whether a band gets this huge cascade of popularity, because the social network is liable to throw up almost any result," he marvels.