The unification of Quantum Mechanics and Relativity Einstein's concepts of space-time contained in his General Theory of Relativity have provided a definition of the time dimension that has been generally accepted for most of the 20 th century.
Relativity attributes physical properties and causality to the dimension of time.
The curvature of space-time is the causality of the force of gravity and defines gravity in those terms. This relativistic model has had remarkable success in explaining and predicting many experimental observations including the expansion of the Universe and the anomalous perihelion shift of Mercury that Newtonian gravity could not explain. However, it has also has some remarkable failures, notably, its inability to accurately explain or predict the quantum nature of energy. For the past century many physicists have spent a majority of their time researching the ideas of Relativity in an attempt to advance our understanding of our universe with little or no success. The same problems Relativity had when was first published still exist.