Physicists have already succeeded in demonstrating the acceleration of light rays on flat surfaces, where the acceleration caused the rays to follow curved paths. However, the new experiment pushed the boundaries of what can be shown in the laboratory. Physicists were the first to demonstrate the acceleration of a light beam in curved space. Instead of moving along a geodesic path (the shortest path on a curved surface), the beam was deflected from the path due to acceleration.
The study, published in the journal Physical Review X, “opens the door to a new field of accelerated beam research. Until now, the acceleration of rays has been studied only in a medium with flat geometry, such as flat free space or in waveguides. In this paper, the optical beams followed curved paths in a curved medium,”says Anatoly Patsik, a physicist at the Israel Institute of Technology.
The successful experiment, carried out by physicists at the Israel Institute of Technology, Harvard University and the Harvard-Smithsonian Astrophysical Center, will increase the research potential for further laboratory research on phenomena like gravitational lensing. By conducting such experiments in the laboratory, scientists will be able to study the phenomena predicted by Einstein's theory of general relativity under carefully controlled conditions.
First, the scientists accelerated a laser beam by bouncing it off a spatial light modulator designed to modulate the amplitude, phase, or polarization of light waves. The bounce of the beam from this device imprints a specific wavefront on the beam, which accelerates while maintaining its shape. The scientists then aimed an accelerated laser at the inside of an incandescent lamp, which was painted to scatter the light and make it visible to researchers.
Scientists observed that moving inside the lamp, the beam deflected the trajectory from the geodetic line. By comparing this motion to a ray that was not accelerating, they found that when there was no acceleration, the ray would follow a line.
This research can become a starting point for future research of phenomena that fall under Einstein's general theory of relativity. Patsik stated that “Einstein's equations of general relativity determine, among other things, the evolution of electromagnetic waves in curved space. It turns out that the evolution of electromagnetic waves in curved space according to Einstein's equations is equivalent to the propagation of electromagnetic waves in a material medium, described by electrical and magnetic susceptibility, which can change in space."
This experiment should give impetus to the development of research on the topic of gravitational lensing and Einstein rings, gravitational blue or redshift, and much more. In the future, scientists plan to study whether plasma beams (in which plasma oscillates instead of light) can also accelerate in curved space.
Ilya Khel
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