Experience how Harry Potter's cloak of invisibility could become a reality

07 July 2011

As thousands of fans descend on Trafalgar Square for the world premiere of the final Harry Potter movie today (7 July), visitors to the Royal Society’s Summer Science Exhibition, just down the road, will have the opportunity to see how scientists are drawing ever closer to making the boy wizard’s magical cloak of invisibility a real possibility.

Theoretical physicist Professor Ulf Leonhardt, from the University of St Andrews, will be exhibiting his work on broadband invisibility and creating the blueprint for a practical cloaking device. His theory uses specially designed optical metamaterials - artificial materials engineered to provide electromagnetic properties – to curve space around the object that is being made invisible.

Professor Ulf Leonhardt Invisibility (6 mins).Leonhardt draws inspiration for his research from the imaginations of his children and literature. The exhibit will use The Invisible Woman from The Fantastic Four to explain the theory of invisibility by light bending. In the stories, she has a mysterious force field with which she can curve space and bend light around her. Research in optics shows, however, that no mysterious force field is needed; the light bending can be done with optical materials. To experience this, visitors will be able to play with sending laser light through an aquarium. The water in the aquarium will contain sugar at different concentrations depending on the depth causing the light beams to bend and even bounce over the bottom of the aquarium.

Visitors to the Exhibition will also find out why invisibility by transparency as seen in H.G. Well's novel "The Invisible Man" is far less likely to become a reality. In the book a scientist makes himself invisible by optically matching every cell in his body to the environment (air).  Visitors will be able to try out a clever trick making "invisible spheres" in water. The spheres represent the cells of the Invisible Man and the water, air. The spheres will literally disappear in front of visitors eyes.

The research may also produce new ideas for optical devices that have not been possible before, such as perfect retroreflectors (e.g. cat’s eyes) for increased visibility and improved microscopes and lenses.

Commenting on his stand at the Summer Science Exhibition, Professor Ulf Leonhardt said:

“Invisibility has fascinated people for millennia. The idea of being able to move stealthily through rooms the way Harry Potter does when he wears his cloak of invisibility is a very appealing one. Technology that enables invisibility has very obvious applications in the defence, aviation and medical industries but it goes far beyond that. I’m hoping that our exhibit will show visitors that what most people would consider magic could become a stuff of everyday life thanks to science.”

The exhibition opens to the public until 6pm on Sunday.