New light shed on Macbeth

Contemporary optical science could have inspired a famous supernatural event in one of Shakespeare's darkest works, new research suggests.

And the bard may have used the emerging tricks with mirrors as special effects when the play hit the stage.

The research, by Australian National University Shakespeare specialist Professor Iain Wright, sheds new light on an eerie scene from Macbeth.

The scene sees Scottish general Macbeth led to his victim, King Duncan, by a floating blood-soaked dagger which points to the monarch's room, beginning Macbeth's murderous rampage in pursuit of the crown.

It is part of a host of supernatural events in a play which is heavy on apparitions as Macbeth tries to fulfil the prophecy of three witches that he will become king.

But Professor Wright's investigation points to an inspiration for the dagger that has a firmer base in reality than a predictable medieval nod to demons and the dark arts.