Work and the space-time continuum

I assume that I am not the only academic who has wished for time travel (and not just because I want to drive a cooler car or take advantage of the stock market).  Grading a stack of papers today reminded me that it is incredibly easy to manipulate the speed at which time passes.  For example:

• In order to slow time to a crawl, grade an error-prone student’s essay with the knowledge that there are 25 more waiting for you when you’re done.  Keep an eye on the clock to note that time has, indeed, nearly stopped.
• In order to accelerate time, take a break to check your e-mail or log onto Facebook.  While you can try to keep an eye on the clock while doing this, you will quickly realize that time has accelerated to the point at which each glance at the clock (seconds apart when grading) reveals the passage of 30 to 40 minutes.

Unfortunately, at this point I have only been able to manipulate the passage of time in the forward direction.  This may be for the best, since I hear there are risks of incest and bleeding ears when traveling backward in time.