  The spread of information networks has not only made it easier for people to
access a variety of information sources but also greatly enhanced the ability
of individuals to disseminate information. Unfortunately, however, the problem
of slander in online social networks shows that the evolving information
network environment does not necessarily support mutual understanding in
society. Since information with particular bias is distributed only to those
communities that prefer it, the division of society into various opposing
groups is strengthened. This phenomenon is called polarization. It is necessary
to understand the mechanism of polarization to establish technologies that can
counter polarization. This paper introduces a fundamental model for
understanding polarization that is based on the concept of spontaneous symmetry
breaking; our starting point is the oscillation model that describes user
dynamics in online social networks.
