Dark matter

I've just thought, I should tell the story of the big bang. You know I'm very sceptical about ghosts and stuff, yet every so often something happens. About six months ago I was in our catering kitchen in the hall. It used to be a solar, a room the Lord used as a private bedroom and living space, it probably dates back to around 1470 or so. There were no visitors in, very few staff, most of them were on their lunch break. On the ceiling above me I heard a massive thump. The last time I heard that kind of sound was when my elderly next-door neighbour fell down last year. Being the first aider I thought there must be a visitor up there who's fallen over, so I (rather reluctantly) went upstairs to look. No-one. In fact no-one in the hall. Nobody had left the front entrance either. Nothing fallen or moved. I couldn't find anything to explain it,it was a mighty big bang though, not something imagined. Very odd.