title: timestamps in rails - datetime or UNIX timestamp?
body: <p>I was currently presenting an project to my professor in university and he didn't like that my rails app used DATETIME to store its timestamps in the database (he doesn't know or seem to like rails anyway :).
  He said this is going to lead to problems due to different timezones and I should save it as UNIX timestamps (integers) to the database.</p>
  
  <p>Now I suppose the people who designed rails had a reason to store it like this, and as the timestamps fields are added automatically to any migration, I wanted to ask you guys</p>
  
  <p>a) if I can modify the rails default migrations to use the UNIX timestamp by default</p>
  
  <p>b) about pros and cons of this approach</p>