title: Is it possible to rewrite history without leaving trace?
body: <p>I have read <a href="https://stackoverflow.com/questions/454734/how-can-one-change-the-timestamp-of-an-old-commit-in-git">this question</a> about changing the timestamp of an old commit.</p>
  
  <p>What I'd like to know is: this kind of operations is destructive (i.e. don't leave any traces) or is it possible to find out that a certain operation was done on the repository? If is it so, how could I do it?</p>
  
  <p>Thanks</p>