Forget 6 Degrees of Separation

From the office, to volunteering with your kid's basketball team, to swapping pictures with favourite vegan chefs on Instagram, social networks are everywhere - online and in real life. And these networks have a lot in common.

Each one involves a series of actors, also called nodes. You can imagine a network like an airline routes map, with cities representing nodes. Some are directly connected, like London and Paris, others have a few stops between, like Aberdeen and Bordeaux.

In a social network, we usually think of nodes as individual people, but they can also be places or events, such as the Eiffel Tower or a basketball game. Next, there are connections among the actors. These include family, friendships and professional relationships. A connection can also be a coincidence, such as being stuck in the same beer queue at a game. Finally, there are degrees of connectivity, or the number of connections an actor has.

Closer than you think

In the late 1920s, Hungarian writer Frigyes Karinthy described the small-world paradox, in which he proposed there are up to six degrees separating any two people on the planet. The small-world paradox is supported by research that shows, even as our population grows, the degrees of separation among us are fewer.

"Relationships between people can be represented in very large, connected graphs," says Jonathan Schaeffer, dean of the Faculty of Science. "When considering degrees of separation, we're talking about the shortest distance between point A and point B on that graph."

It's no surprise that our digital social networks are changing our graphs dramatically.

"Digital social networks transcend all sorts of boundaries, such as geography and traditional social circles," Schaeffer says. "People connect for all sorts of reasons and in all sorts of places where in-person connections may never have been made." The sweet vegetable bahji recipe you snared on Instagram from that chef in Buenos Aires is testament to this.

But there is an important distinction to make between social media and social networks: they are not the same. Social media platforms, such as Facebook, Twitter and Instagram, support and facilitate social networks that may or may not otherwise exist.

A paper published by Schaeffer and colleagues in 2011 showed there were just 3.44 degrees of separation between users on Twitter - nearly halving Karinthy's original hypothesis. "The more people we have on this planet, the more connections we have, and the closer we become to one another," Schaeffer says.

Vast applications

"If we have data that show the relationships between entities, we can use social-network analysis to learn a great deal about it," says Osmar Zaïane, computing science professor and scientific director of the Alberta Machine Intelligence Institute. An expert in data management and information mining, he's familiar with the power of social networks. In the digital age, Zaiane says you can see how data management and mining affects everything from your consumption of entertainment to your health-screening behaviours.

When we understand how actors interact and, more specifically, how actors with similar features interact, we can begin to understand network characteristics, ranging from power relations to other connections we didn't even realize were there.

Biologists can use social-network analysis to understand the ways in which proteins interact. Businesses can discern customer behaviour. Public health practitioners can track health outcomes. Linguists can uncover new connections among languages. Netflix users can receive eerily accurate recommendations based on what they and others in their network are watching.

Everyone you never knew you'd know

For Zaïane, the most exciting implications behind social-network analysis lie in our new-found ability to see the future, kind of. Take criminology, for example.

"Say you've mapped the criminal activity of a certain network, outlining events, people, places and objects," says Zaïane. "Using predictive analysis, we can see who may not be connected now but may be connected in the future. Retroactively, we can also see who may have been connected in the past, but is no longer connected now."

Social-network analysis is the tool that taps the data to fight crime or suggest movies. And it demonstrates that, though the mountains are high and the oceans are wide, it really is a small world.

This article originally appeared in fall 2017 issue of Science Contours