Einstein had come close to the reality after publishing his general relativity theory in 1915. But his general relativity theory which is essentially invalid prevented him to move further to realize the truth. To realize the above statement we have to have some information of before and after the general relativity publishing time and so let us have some of that information given below as presented by modern day scientific communities.
• The concept of aether was used in several theories to explain several natural phenomena, such as the traveling of light and gravity. In the late 19th century, physicists postulated that aether permeated all throughout space, providing a medium through which light could travel in a vacuum. Propagation of light waves was then assumed to require the existence of a waving medium; in the case of light waves, this was considered to be a hypothetical luminiferous aether. However, the various attempts to establish the properties of this hypothetical medium yielded contradictory results.
• The famous Michelson–Morley experiment of 1887 showed no differential influence of Earth motions through the hypothetical aether on the speed of light and this result has been interpreted as meaning that no such luminiferous aether exists. By the 1900s, physicists were unable to reconcile the contradictions and so physics was in crisis.
• In 1905, Albert Einstein published his Special Theory of Relativity. Einstein postulated that the laws of physics are the same for all observers in uniform translational motion, and that the speed of light in vacuum is constant regardless of the motion of the light source or observer. This abolished the necessity of a stationary luminiferous aether in classical physics.
• However, later in 1920 at the University of Leiden, Einstein delivered an address stating: "Recapitulating, we may say that according to the general theory of relativity space is endowed with physical qualities; in this sense, therefore, there exists an aether. According to the general theory of relativity space without aether is unthinkable."
The book ‘Unique Phenomena’ resolves these fundamental contradictions with definitive clarity, revealing the true nature of space and the universe.