我怎样才能找到事件发生以来的时间？

The event returns a standardized timestamp in the format of "Sat Oct 25 21:55:29 +0000 2008" How can I compare this with the current time in PHP so that it gives me the result in a form like "It has been 15 minutes!" or "It has been three days!" Also, how can I get the current time?The event returns a standardized timestamp in t