New insights have been provided by the visual effects team that created Christopher Nolan’s Oscar-nominated film Interstellar. They now know more about black holes and are turning science fiction into science reality. The scientists explain the code that generated the iconic black holes, wormholes and other celestial bodies in a paper they published in Classical and Quantum Gravity. Interstellar visual effects team is made up of Double Negative, a London-based company, and Kip Thorne from Caltech. They also explain how the innovative code led to their sciencific discoveries. A view of a starfield affected by gravitational lensing. Image: Double Negative. They discovered that when the camera was placed close to the fast-spinning black holes, caustics create over 12 images of stars in the bright and thin galaxy. They found that the images are concentrated at one end of the shadow created by the black hole. Multiple images are created when space is pulled into a spinning motion by the black hole and the caustics are stretched around it several times. How would black holes affect people? The effects of caustics have never been calculated for cameras located close to black holes. Scientists now have an idea of how a person would view the hole from orbit. Computer code created by the team mapped millions of light beams’ paths and the evolution of their cross-sections through the black hole’s spacetime. This made the discovery possible. The team was able to produce images with incredible clarity and smoothness of Gargantua’s black hole and wormhole. A flat disk-like, gas structure, the accretion disc, spirals rapidly around larger objects, like a star, white dwarf, or black hole. The movie’s signature image, which featured a photo of a split shadow, showed the parts of an accretion disc swinging upwards and downwards below Gargantua’s shadow. Gravitational lensing distortion The mysterious distortion of the glowing disc was due to gravitational lensesing. This is when light from distant objects becomes distorted and distorted around the block between the viewer’s eyes and the object. Einstein’s theory of general relativity predicted gravitational lensing. The black hole causes this lensing because it creates an extremely strong gravitational field. It literally bends spacetime around itself like a bowling ball on a taut sheet. The visual effects team discovered that using one light ray per pixel of a code – in this instance, for an IMAX image, a total millions pixels – caused flickering. Oliver James (chief scientist at Double Negative) said that to get rid of flickering, and create realistically smooth images for the movie’s production, they changed their code. We used Einstein’s equations to trace the individual paths of the light rays. Instead, we traced the shapes and distorted paths of the light beams. Smooth images are what we also need. Mr. James said that DNGR could be adapted to scientific research. James explained that a light beam from any caustic surface is reflected by the black holes and becomes a bright spot of light. The camera close to the blackhole captures all of the caustics except one. This causes the sky-wrapping of caustics many times. DNGR simulation films showed that as the camera orbited a black hole, the caustics created and destroyed countless stellar images. They were able to see 13 multiple images of one star and 13 images from the bright, thin galaxy within which the black holes exist. The multiple images were created only when the black was spinning quickly and on the nearest side of its black hole. This was where the black’s whirling area was moving towards the camera. They deduced that this was because the shadow of the hole was flinging the images outside. The scientists discovered that the space was moving away from the camera on the opposite side. There were many images of stars, but the space whirling had compressed them so that they weren’t visible in simulations. Citation: “Gravitational lenses by spinning black holes” in Astrophysics and the film Interstellar. Paul Franklin, Eugenie Von Tunzelmann and Kip S. Thorne. Classical and Quantum Gravity 065001. doi: 10.1088/0264-9381/32/6/065001. 10/-9381/32. Video of Starfield in gravitational lensing
