Article history: Received 9 June 2005 Received in revised form 13 September 2008 Accepted 3 November 2008

The confrontation between general relativity (and its theoretically most plausible deviations) and experimental or observational results is summarized. Some discussion is devoted to the various methodologies used in confronting theory and experiment. Both weak-field (solar system) and strong-field (binary pulsar) tests are discussed in detail. A special discussion is devoted to the cosmology of...

We propose a Lorentz-covariant theory of gravity, and explain its theoretical origins in the problem of time in Newtonian physics. In this retarded gravitation theory (RGT), the gravitational force depends upon both retarded position and velocity, and the equations of motion are time-asymmetric retarded functional differential equations. We explicitly solve these equations, under simplifying as...

The confrontation between Einstein’s gravitation theory and experimental results, notably binary pulsar data, is summarized and its significance discussed. Experiment and theory agree at the 10−3 level. All the basic structures of Einstein’s theory (coupling of gravity to matter; propagation and self-interaction of the gravitational field, including in strong-field conditions) have been verifie...

The XXVI Encontro Nacional de Fı́sica de Partı́culas e Campos (ENFPC: Brazilian National Meeting on Particles and Fields) took place in São Lourenço, MG, Brazil, in October 2005. I was invited to deliver the summary talk on the area of gravitation and cosmology, in which I took the opportunity to briefly present a historic sketch of the ideas related to relativity, gravitation and cosmology in ge...

We consider the Friedmann-Robertson-Walker cosmologies of theories of gravity that generalise the Einstein-Hilbert action by replacing the Ricci scalar, R, with some function, f(R). The general asymptotic behaviour of these cosmologies is found, at both early and late times, and the effects of adding higher and lower powers of R to the Einstein-Hilbert action is investigated. The assumption tha...

Data mining is a process of discovering and exploiting hidden patterns from data. Clustering as an important task of data mining divides the observations into groups (clusters), which is according to the principle that the observations in the same cluster are similar, and the ones from different clusters are dissimilar to each other. Subspace clustering enables clustering in subspaces within a ...

We propose a mathematical model for vision-based autonomous navigation on general terrains. Our model, a generalization of Mallot’s inverse perspective, assumes the direction of gravity and the speed of the mobile agent to be known, thus combining visual, inertial, and navigational information into a coherent scheme. Experiments showing the viability of this approach are presented and a sensiti...

Einstein’s general theory of relativity [1] is a successful classical theory of gravitation inasmuch as it agrees with all experimental data available at present [2]. To develop a microphysical gravitation theory, it may prove useful to investigate the extent to which the basic physical tenets of general relativity conform with the fundamental principles of the quantum theory. This is the gener...