A direct link to the video: http://www.youtube.com/watch?v=6S8JFoT6BEM
I have to admit I didn't really understand your answer:
> [When you try to forget data] you're making a subset of this computer that will not compute when it tries to use this information.
Could you elaborate a little on what that means, and how you'd apply it in practice. If I wanted to not just make data inaccessible but actually purge it from my machine, how would I do so?
If an event depends on data that's been deleted, that event never happened. But, at the Unix level (which can generate any events it wants), we can generate another event which reports the error. So it's not like things fall silently down the hole, either. (For the same reason, you can also get the stack trace of the infinite loop that was interrupted by your ^C.)