Well. I was babysitting, and they had a sofa delivered while I was there. (this was fun) As they tried to get the sofa into the living room, they discovered that it couldnt be done, with out removing the door (angles and suchlike), and had to take it in through the back door, the family room, the kitchen and the dining room, just in an attemt to get it into the living room. Now, all this would be a fairly uninteresting story, except that it reminded me of something, which I promptly took out of the library, and will shortly quote to you.
"[The sofa] is stuck halfway up a long flight of stairs whihc leads up into my flat. As far as I can make it out, the deliverymen got it partway up the staris, got it stuck, turned it around any way they could, couldn't get it any further, and then found, curiously enough, that they couldn't get it back down again. Now, that should be impossible."
"Odd," agreed Reg. "I've certainly never come across any irreversible mathematics involving sofas. Could be a new field."
..."I could just saw it up and throw it away, but I can't believe that there isn't a logical answer. And it also made me think - it would be really useful to know before you buy a piece of furniture whether it's actually going to fit up the stairs or around the corner. So I've modeled the problem in three dimensions on my computer - and so far it says no way...that it can't be done. I told it to compute the moves necessary to get the sofa out, and it said there aren't any. I said, "What?" and it said there aren't any. I then asked it, and this is the really mysterious thing, to compute the moves necessary to get the sofa into its present position in the first place, and it said that it couldn't have got there. Not without fundamental restructuring of the walls."
Douglas Adams,
Dirk Gently's Holistic Detective Agency
I'd also like to mention that this is the book that introduced me to the idea of Schrodinger's Cat, which in turn led me to become the person that I am today. Thank you, Douglas Adams. *mourns*
