Forum Content Management System exactly like stackoverflow.com

I wish to build a forum to facilitate the discussion in my research field. And I am looking for some easy way out, like forum content management system which allow users to post/answer questions, but most importantly, let users rate the posts and answers, so good answers will ranked up and knowledge can be easier to find in my research field. That is to say I wish to build a stackoverflow.com for my specif research field. Do you know how can I do that quickly without writing too many codes myself? If there are similar content management system available that provide this function, that will be great! I just need some suggestions on this. Thanks very much indeed for your help.