A century after Albert Einstein came up with the theory of relativity, scientists at the Israeli university he helped found described a proof for one of the basic assumptions underlying that theory: the idea that all light particles propagate at the same speed, physics news website Phys.org reported Monday.
The research, published Monday in the journal Nature Physics, found that light particles, or photons, traveling for billions of years from a distant gamma-ray burst toward Earth arrived with a fraction of a second of each other, the report said.
The data, which show that the photon speed was uniform even though the light particles had different energies, was analyzed by scientists from the Hebrew University of Jerusalem, which Einstein helped found, as well as Israel's Open University, Italy's Sapienza University of Rome and France's University of Montpellier.
The research backs up Einstein's theory because the divergence of the speed and energy measurements demonstrates that they are two independent variables.
The data obtained by NASA's Fermi Gamma-ray Space Telescope also call into question the theory of "space-time foam," which maintains that space has a foam-like structure on a microscopic scale. The fact that the foam-like structure, if it exists, did not cause substantive variations in the photons' speed shows that either there is no such strcuture or it is smaller than previously thought, said Phys.org.