Life's little mysteries

It's just one of those combination heat, light and fan thingies that you see on every second bathroom ceiling. Nothing remarkable at all. Except that from time to time it decides to switch on the fan. After a minute or two it switches it off again. Is it picking up a frequency from some neighbouring electrical appliance? Is it the ghost of a former resident who resents our intrusion? Did some horrid crime occur in our bathroom? Are aliens using our house as a comms centre?

Will we ever know?