Saturday, November 24, 2012
Antigravity from Supergravity
As 2013 approaches, one may be left wondering where all the marvelous 2015 inventions of Back to the Future 2 are. It seems the motorized Nike's worn by Marty McFly do exist (as Nike Air MAGs), but as of now cost a pretty penny to purchase. However, the shoes aren't even the coolest invention featured in the movie, as hoverboards steal the spotlight in the 1989 film.
Let's suppose hoverboards may be possible. How will they work? Could they be a type of antigravity device? Antigravity turns out to be quite natural in extended supergravity theories, as pointed out by the late Joel Scherk. The supergravity multiplet in the N=2,8 cases contains in addition to the graviton, a spin-1 vector field (graviphoton) and in the N=8 case, a graviscalar. The graviphoton behaves like a massive photon, prone to couple with gravitational strength, and unlike the graviton may provide a repulsive (as well as attractive) force, giving rise to a type of antigravity. Could a real life hoverboard operate using graviphoton fields? Perhaps real life hoverboards will employ superconductor/topological insulator pairs to accomplish the needed levitation effect. Stay tuned.