  According to the World Economic Forum, the diffusion of unsubstantiated
rumors on online social media is one of the main threats for our society.
  The disintermediated paradigm of content production and consumption on online
social media might foster the formation of homophile communities
(echo-chambers) around specific worldviews. Such a scenario has been shown to
be a vivid environment for the diffusion of false claims, in particular with
respect to conspiracy theories. Not rarely, viral phenomena trigger naive (and
funny) social responses -- e.g., the recent case of Jade Helm 15 where a simple
military exercise turned out to be perceived as the beginning of the civil war
in the US. In this work, we address the emotional dynamics of collective
debates around distinct kind of news -- i.e., science and conspiracy news --
and inside and across their respective polarized communities (science and
conspiracy news).
  Our findings show that comments on conspiracy posts tend to be more negative
than on science posts. However, the more the engagement of users, the more they
tend to negative commenting (both on science and conspiracy). Finally, zooming
in at the interaction among polarized communities, we find a general negative
pattern. As the number of comments increases -- i.e., the discussion becomes
longer -- the sentiment of the post is more and more negative.
