7,000 years to render 'gravity' on one CPU...

Another Gravity post, and no I still haven't seen this film yet, but what caught my eye was a short article by Al Moloney for BBC News Technology explaining how visual effects firms are transforming the film industry and in one paragraph discussing the digital aspects that make the movie, (which I though was unbelievable) he states:

"The end result is a film that is about 80% composed of digital shots. Each frame took around 50 hours to render fully and if the entire film had been rendered using a single CPU processor then it would have taken about 7,000 years."

7.000 years! is that even conceivable? watching our little low res 3D animations at college take weeks to render just over 1000 frames, this really puts in into perspective about the sheer magnitude of these movies and how much time it actually takes, not just to film and edit the movie, but to finally render the shots. 50 HOURS FOR ONE FRAME. Wow.  is all.