Fluctuations in intensity are a result of the interference of light emitted separately from the surface of the star - visible as a pattern of light dots in the images produced - and allow conclusions to be drawn about the size of the object that is observed.Īs paths of light in curved space tend to converge or diverge much more frequently than in flat space, the size of the dots changes depending on the curvature. The fluctuations in light intensity measured by the two telescopes are then compared. In this measurement technique, two telescopes are set up some distance apart and focused on the star that is to be examined. In their work the researchers studied intensity interferometry, pioneered by the English physicists Robert Hanbury Brown and Richard Twiss, which is used to determine the size of stars that are close to the sun. When transferred to astronomical observations, this means that light that reaches us from far away stars carries valuable information about the space that it has travelled through. Conversely, it is also possible to learn about the curvature of a surface itself by analysing the propagation of light. By changing the curvature of the surface it is possible to control the propagation of light. As the light propagated it behaved in the same way that it does when deflected by huge masses. To do so they captured light in a small area close to the surface of a specially made object and forced it to follow the course of the surface. The researchers examined the effects of this intrinsic curvature of space on the propagation of light in their experiment. The curvature of the surface of a sphere is an intrinsic property that can't be changed and has an effect on geometry and physics inside this two-dimensional surface.' 'A well known example of this is world maps that always show the surface in a distorted way. 'For example, while you can easily unfold a cylinder or a cone into a flat sheet of paper, it is impossible to lay the surface of a sphere out flat on a table without tearing or at least distorting it,' says Vincent Schultheiß, a doctoral candidate at FAU and lead author of the study. ![]() However, not all curved surfaces are the same. Instead of changing all four dimensions of spacetime, they reduced the problem to two dimensions and studied the propagation of light along curved surfaces. Ulf Peschel from Friedrich Schiller University Jena used a special trick to examine the propagation of light in such curved spaces in the laboratory. In this curved space, celestial bodies and light move along geodesics, the shortest paths between two points, which often look anything but straight when viewed from the outside. According to Einstein's general theory of relativity, gravity can be described as the curvature of four-dimensional spacetime.
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