title: Change today's date and time in php
body: <p>Is it possible to change php's current date and time (something like set_time(strtotime('1999-09-09')) so when i call time() it will return me timestamp for 1999-09-09? I need to set it globally for whole app. </p>
  
  <p><strong>EDIT</strong></p>
  
  <p>I already have one old app and i need to make possible to set up current date. 
  I can't accept any custom functions. Imagine i should review all the code and replace every time() call. Even if i'll do so then it will not help because there are functions like getdate() which i need to replace as well.</p>