In 1887 the Michelson-Morley experiment was performed, which was supposed to detect the motion of the Earth relative to the ether (which corresponds to the space), i.e. the medium in which light would manifest itself, and therefore the only one relative to which its speed could be really the same in all directions, and that is, really isotropic.But the experiment found that the speed of light is isotropic relative to the Earth too, and therefore did not detect any motion relative to the ether.In order to justify this negative result, Lorentz hypothesized that all objects that move in the ether undergo a slowing down of time and a length contraction in the direction of motion, thus making the speed of light appear isotropic, while in reality it is not.Instead, Einstein justified this result by arguing that light propagates in a vacuum and that its speed is isotropic in all reference frame, regardless of the motion between them, specifying however that this is a stipulation and, therefore, not a real phenomenon, so the isotropy can only be apparent. But Einstein later considered this isotropy as real and the scientific community still considers it this way, overbearingly, since it does not accept to question this thesis of his.In truth, it is precisely thanks to the real slowing down of time and the real contraction of matter, that the speed of light appears isotropic. And it is a very useful appearance, because based on it you can operate the GPS system. Which cannot work according to reality, because the precise speed of the Earth relative to the ether is not known and, therefore, not even the real speed of light relative to the Earth, which would be needed to make the GPS work according to reality.But this appearance does not allow for the correct calculation of the speed and distances of celestial objects, so, by using it anyway, the scientific community has obtained a complicated model of the Universe that is incompatible with observations, and whose expansion results in acceleration, rather than deceleration, as it should be according to reality.