You’re on the job hunt. You’ve probably reached out to everyone you know. Your best friend, your coworker, but here’s something you probably don’t know: The people closest to you are the least likely to help you land your next role. It’s a harsh truth first discovered by sociologist Mark Granovetter.

Granovetter found that your close ties share a professional bubble. You hear the same rumors, scroll the same job boards, and often know the same people. But that random coworker from three jobs ago, or the person you met once at a conference? Well, they live in a different social world. Granovetter called these casual acquaintances, “weak ties,” and as it turns out, they’re the secret to your next job opportunity.

This theory has been widely accepted but has been considered tricky to prove at a larger scale, that is until 2022 when a 5-year experiment was published in Science. Researchers partnered with LinkedIn to tweak the “People You May Know” algorithm for over 20 million users, nudging some towards stronger connections and others toward weaker ones.

The experiment tracked 2 billion new connections, 70 million applications, and 600,000 accepted jobs. The verdict? Granovetter was right, but the plot twist: far-distant strangers weren’t the sweet spot, instead “moderately weak ties,” or people with around ten mutual contacts, led to the highest rate of job mobility.

This effect has been especially powerful in tech and digital industries, where word of new roles travels fast through loose networks. So what does this mean for you and your job search? Reaching out to a former colleague you haven’t spoken to, would that be weird or intrusive? It might be one of the single highest-leverage moves you can make.

If your network consists entirely of close friends, you’re sitting on an opportunity to expand. The people who consistently land great roles aren’t master networkers. They keep a wide, loose network alive over time, never letting old ties fade away completely.

So don’t be afraid to reach out and re-engage those casual connections. A simple check-in could easily open the door to your next big career opportunity.