# The key to the weak-ties phenomenon

## TL;DR

This paper investigates the underlying causes of the weak-ties phenomenon in social networks, revealing that mutual friends often do not drive weak ties, which are instead influenced by other factors such as collaboration preferences.

## Contribution

It introduces a data-driven network science approach to uncover the causal mechanisms behind the weak-ties phenomenon, challenging previous assumptions.

## Key findings

- Mutual friends are not the primary cause of weak ties.
- Weak ties often result from a preference for direct collaboration.
- Large numbers of mutual friends are associated with weak ties, but not causally.

## Abstract

The study of the weak-ties phenomenon has a long and well documented history, research into the application of this social phenomenon has recently attracted increasing attention. However, further exploration of the reasons behind the weak-ties phenomenon is still challenging. Fortunately, data-driven network science provides a novel way with substantial explanatory power to analyze the causal mechanism behind social phenomenon. Inspired by this perspective, we propose an approach to further explore the driving factors behind the temporal weak-ties phenomenon. We find that the obvious intuition underlying the weak-ties phenomenon is incorrect, and often large numbers of unknown mutual friends associated with these weak ties is one of the key reason for the emergence of the weak-ties phenomenon. In particular, for example scientific collaborators with weak ties prefer to be involved in direct collaboration rather than share ideas with mutual colleagues -- there is a natural tendency to collapse short strong chains of connection.