An unnatural event in which something very unlikely happens at almost exactly the same time as, or very shortly afterwards, it has just been mentioned. Deeply seated in the Laws of Improbability and Chaos Theory, a coincidence is unlikely to happen unless you talk about it first.
- the Old h2g2 Writing Team

Life is a funny thing and the world can be very small. You head off on a round the world cruise, catch a taxi in a small far eastern city only to find out your taxi driver's brother was once engaged to your aunt. Only that very morning you were remarking that you ought to send her a postcard. Or perhaps you decided that you would visit an obscure art gallery only to find a long lost friend in the cloakroom. People love a good coincidence - it litters our literature and culture. Think Pink Floyd's Wish You Were Here and The Wizard of Oz. I bet you didn't know that there was a tornado in Kansas the day Judy Garland died.

Other people argue that coincidence is nothing of the sort. For example, in a random a selection of 23 h2g2 Researchers there is a 50/50 chance that two of them will share the same birthday. This is not a coincidence but mathematically probable. Equally Kansas has a lot of tornadoes.

This week, we want to know...

• Do you believe in coincidence?

• Or do the laws of chance mean that sometimes bizarre things are going to happen?

• Have you ever experienced a bizarre coincidence?

• Have you ever met a long lost friend in a strange and unlikely place?

• Do you have a number that appears regularly in your life?

• Have you known the instant that something happened to a close friend or relative?

• Or is it all a load of rubbish?