Over 30 Muggles gathered at the McLennan Physical Laboratories on Friday hoping to find out if it was possible to make an invisibility cloak, or if they could ever actually go through a wall to King’s Cross Platform 9¾. Grad students Michael Zedler and Yaser Khan spoke on “The Physics of Harry Potter” as part of the Magic Wand Ownership lectures, organized by the physics department.
Zedler first gave a short history of invisibility within mythology and literature. His examples included the myth of Perseus and the Song of the Nibelungs, which features heroes who use a cap of invisibility to aid them in their quests.
“The difference between Harry Potter and the other figures of mythology is that Harry Potter is purely good while the others used it solely for temptation,” Zedler said, drawing laughter from the audience.
He then moved the discussion onto the scientific aspect of invisibility. While it is not possible to achieve complete physical invisibility, it is possible to appear invisible on tracking devices like radar.
Zedler specializes in “metamaterials,” which are engineered to have properties not readily available in nature. Zedler demonstrated that such material would be able to absorb electromagnetic energy, thus enabling a kind of “cloaking technology.”
Khan’s presentation focused on bending light as a way of passing through objects. He spoke about “tunneling,” in which light passes through a barrier to reach the other side.
“This is analogous in some sense to Harry Potter walking through a wall,” said Khan. To demonstrate tunneling, Khan had each of the audience members take a plastic cup of water from the front of the room and press their fingers against it. Each person could see their fingerprint through the glass. But if they dipped fingers in the cup of water and then pressed it against the cup, the fingerprints would be scattered by water.
Khan said that while it was possible for particles at the atomic and subatomic level to pass through barriers such as brick and wood, audience members should refrain from trying to run through walls at home.
In the question period that followed, one audience member asked Zedler, “So, how much is it going to cost to build my starship?”
“I’m happy if it works for something the size of a banana,” Zedler replied, emphasizing the expense of producing of metamaterials and how difficult it would be to cloak something on the scale of a “starship.”
