© Physical Review LettersGlow with the flow
According to Einstein's general theory of relativity, gravity is the result of an object's mass deforming space itself, like a bowling ball on a trampoline. To model how light's path would change in space curved by gravity, Ulf Peschel of the University of Erlangen-Nuremberg in Germany and colleagues constructed smooth 3D objects and sent laser beams shooting along their surfaces (Physical Review Letters, in press).
They took advantage of the fact that light bends, or refracts, when it moves from one medium to another. In their simplest experiment, they shot laser light at the edge of a solid glass sphere. The angle of the beam was chosen so that the light - initially travelling in air - would be bent just enough when it entered the glass that it would keep reflecting off the inside surface of the sphere, and so travel along it. When the light inside the sphere reflected off its inner surface, some was also transmitted through the glass, creating a glowing ring on the outside surface (see image).
The team also constructed an object shaped like two trumpet bells stuck end to end - called a hyperbolic surface. The object was made out of aluminium and then coated with oil. Light sent into the oil layer was confined there, bouncing between the metal and air boundaries. The beam spread out ever more quickly, generating a trumpet-shaped glow.
© U Peschel et alLaser light has been trapped on two different curved surfaces
The experiments help visualise how light travels in space warped by gravity. The sphere, for instance, represents how space is bent around a star or other mass - light passing through this warped space bends in an effect called gravitational lensing. The hyperbolic surface, which has so-called negative curvature because its surface curves up and down at the same time, like a saddle, just might represent the shape of the universe.
"It's a beautiful fundamental experiment," says Ulf Leonhardt of the University of St Andrews in the UK, who was not involved in the work. "It's just fun, good physics."
Space is not curved. Quantum states are more accurate than Albert's attempt to explain away gravitation. The best description of gravity is of ther universal pressure, emanating from the aether, also known as zero point energy or the Casimir effect, being obstructed by nearby bodies that shelter the object from that direction, causing the pressure to push the object towards that body and vice versa. Think of two boats at sea close to one another. As waves wind and currents operate, they push them together, as they each shelter the other from these various effects. Newton even conceived of this explanation, but Einstein proponents want this forgotten for whatever reason!