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Technology takes the chance out of chance encounters

Imagine your kindergarten sweetheart is standing next to you on the train platform, or the person sitting next to you in the theater happens to share your avid interest in antique trains. How would you ever know?

Until now, we've relied on chance. But this may not be so in the future, thanks to Serendipity, a mobile phone application that can instigate interactions between you and people you don't know--or think you don't know--but probably should.

Serendipity, a form of next-generation networking, was developed by Nathan Eagle, a graduate student and Media Lab Europe Fellow working with Alex (Sandy) Pentland, the Toshiba Professor of Media Arts and Sciences in the Media Lab's Human Dynamics group.

The system uses Bluetooth, an RF (radio frequency) protocol that works like a low-power radio in most cell phones, sending out a short-range beacon. "Think of it as each person having a 16-foot bubble around them, blinking out a unique ID," Eagle said. "When two or more people running Serendipity come into the same 'bubble,' their IDs are sent to our server, which looks for their profiles. If there's a match, each gets the other's name, thumbnail photo and common interests on his or her cell phone." Then it's only a matter of introductions.

And it's quick. The server scans for IDs every 60 seconds and only takes about five seconds to find a match, so the whole sequence takes about a minute at the most.

How does the server know about your interests? Just like web-based social network systems like Friendster or, Serendipity depends on profiles that users write about themselves. But Serendipity is unique because it allows the user to "weight" his or her profile to emphasize interests that are of greatest importance to the user's current social situation.

Serendipity has implications beyond social or professional matchmaking. It has potential as a tool for knowledge management, with people using the database not only for social purposes but also to find someone who can solve a particular problem, or perhaps to connect within a large company. By tracking interactions, it could also be used to show companies or planners how people are using space. Even its current matchmaking capability could be expanded; "for example, at a conference it could help you find your colleagues who, unbeknownst to you, have ducked out for Chinese food," Pentland said.

"Because Bluetooth is sending out the 'ping,' the only thing we're doing is correlating that unique ID with information about the person, which makes this a very versatile and lightweight system. This is important because to date, there's no universal operating system like Windows for cell phones, which makes it harder to scale," Eagle said.

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(This story was originally published in the April/May issue of Frames.)

A version of this article appeared in MIT Tech Talk on June 9, 2004 (download PDF).

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