It has been known for several decades that the rest energy of all matter in space is essentially equal to the total gravitational energy in space. The Dynamic Universe model introduced in this paper studies the equality as a dynamic zero-energy balance of motion and gravitation in spherically closed space. In such a solution time is absolute, the fourth dimension has metric nature, and relativity appears as the measure of the locally available share of total energy in space. The study of the zero-energy balance in spherically closed space can be based on few postulates and the derivation of predictions for local physical phenomena and for cosmological observations can be carried out with fairly simple mathematics essentially free of additional parameters.;In all interactions in space the total energy is conserved. A clock in motion in space does not lose time because of slower flow of time but because motion in space diverts a share of the total energy of the device thus leaving less energy for the oscillation running the clock. In the DU framework a local state of rest can be related to the state of rest in hypothetical homogeneous space, which serves as a universal frame of reference for all local phenomena in space. The Dynamic Universe model discards the space-time marriage, the relativity principle, the Lorentz transformation, the equivalence principle, and dark energy. The DU model also discards the postulation of the constancy of the velocity of light but explains why the velocity of light is observed as being unaffected for observers in motion and for observers at different gravitational potentials.;In celestial mechanics, the Dynamic Universe leads to stable orbits down to the critical radius of local singularities (black holes), shows the perihelion shift of eccentric orbits, the Shapiro delay, the bending of light, etc. In the Dynamic Universe, gravitationally bound systems like planetary systems, galaxies and galaxy groups expand in direct proportion to the expansion of space. As a consequence, the Euclidean appearance of the angular sizes of galaxies is predicted. The DU’s prediction for the magnitude versus redshift of standard candles is in an excellent agreement with recent supernova observations without assumptions of dark energy or free parameters.;The Dynamic Universe means a major change in the paradigm but offers a platform – with relativity built in and a firm anchor to human conception – to doctrines like Maxwell’s equations and electromagnetism in general, thermodynamics, celestial mechanics, and quantum mechanics.

Keywords: Relativity, unification, cosmology