Quote of the Day - Part Two:

"An SEP is something we can't see, or don't see, or our brain doesn't let us see, because we think that it's somebody else's problem.... The brain just edits it out, it's like a blind spot. If you look at it directly you won't see it unless you know precisely what it is. Your only hope is to catch it by surprise out of the corner of your eye.

The technology required to actually make something invisible is so complex and unreliable that it isn't worth the bother. The "Somebody Else's Problem field" is much simpler and more effective, and "can be run for over a hundred years on a single torch battery."

This is because it relies on people's natural predisposition not to see anything they don't want to, weren't expecting, or can't explain."

-Ford Prefect, Douglas Adams "Life, the Universe and Everything"