How do I refresh a view (or a page) after a new comment has been posted? I have a view that displays comments for a node. 
When user1 posts a new comment then that comment appears automatically in the view for user1. But for user2 viewing the same node, the new comment does not appear automatically without a page refresh (ie, the view does not get refreshed automatically).

I have tried to find an event in rules to trigger an event that could look like "refresh page" or "refresh view".

Any hint?
Try using Views Auto-Refresh module. 


  A module to refresh a view after a specified time interval. Includes
  advanced options to avoid reloading the whole view, and to avoid
  causing a full Drupal bootstrap at each refresh.


If you are looking for REAL realtime update you should use some server side javascript like nodejs, to push event to the dom. 

also there is nodejs module for Drupal.

A great tutorial