Hard drives are amazing feats of engineering!

Geeky vid alert. I had no idea how precise hard drives are. The one sitting in your computer right now is spinning at about 120 times a second with the read head floating on air just 10 nano meters above the disk! That's like NASA space age shit! Think how flat the disk has to be so it doesn't break it.
This is why it's important to remember to back up before the tiniest bit of crap kills the thing altogether.