This paper reviews empirical evidences from several optical experiments on the earth showing the possiblility to detect the motion of the Earth. Four different experiments with different technical means, and from widely separated places in time and space, point towards solar motion in a plane with right ascension of 75º. However, there is no agreement on the declination, which seems to be large. This evidence contradicts the widely accepted heuristic principle that the motion of the Earth cannot be detected by terrestrial experiments, and opens the door for a reinstatement of the currently forbidden concept of absolute space S. A closed finite Newtonian universe has interesting cosmological implications, as compatibility with the variation of speed with distance (without expansion), and the appearance of new acceleration term of the same order of magnitude as the Modified Newtonian Dynamics (MOND) cut-off, thus offering an alternative explanation to the dark matter and MOND hypotheses.

One of the aims of this paper is to draw attention to long-lived problems in modern physics, which must be solved. We want to address here some touchy questions, dealing with some of the most cherished notions of the 20^th century physics. By the end of the 19^th century, the positivistic school called attention to the importance of measurement in the physical sciences. Following this lead, by the 1930s, the Copenhagen interpretation of quantum mechanics went to the extreme view that things only exist when they are measured. It is well-known that Einstein was very critical of this philosophical stance. It is worthwhile to recall his famous rhetorical question to one of his collaborators: "Is the moon there when we do not look at it?"

Einstein, however, was not equally critical with his own ambiguous position regarding his notions of space and the ether that fills it (Kostro, 2000, p. 242). In the context of his general theory, Einstein was for the concepts of ether and absolute space. In the words of Einstein (1983, p. 17), "Newton might no less well have called his absolute space `Aether'; what is essential is merely that besides observable objects, another thing, which is not perceptible, must be looked upon as real, to enable acceleration or rotation to be looked upon as something real".

Evidently, Einstein, in this context, accepted the existence of physical entities, independently of measurement, and even of perception. Note also that acceleration and rotation are set on an equal footing. Since rotation requires the presence of some agent producing the requisite centripetal acceleration, the other term `acceleration' must be understood as `linear' acceleration. Hence, one of the many possible ways to characterize absolute space Σ is: "Σ is the space where acceleration exists". Of course, according to Einstein's principle of equivalence, acceleration of gravitational origin also exists in S. We completely concur with this view.

Physics Journal, Absolute Space, Michelson-Morley Experiment, Miller Experiment, Dark Matter, Anomalous Cosmic Tangential Velocity, Cosmology Models, MOND Model, Centripetal Acceleration, Aether, Newtonian Universe, Restricted Theory of Relativity, RTR, Eidgenössische Technische Hochschule, ETH.