Assumption on which the theory rests
Photons from a source (e.g. a star) travel through empty space and always have the same speed relative to an observer regardless of the observer’s velocity toward the source or away from the source.

Assumption on which the theory rests
Photons from a source are propagated at a constant speed through a medium, and as a consequence their speed relative to an observer depends on the observer’s velocity through the medium.

Ability to predict and explain phenomena
Accurately predicts phenomena (e.g. the decrease in aging of a traveling clock, or the increase in mass of a particle moving at high speed in an accelerator). Does not explain why the predicted phenomena occur and, consequently, has been difficult to comprehend.*

Ability to predict and explain phenomena
Accurately predicts phenomena and explains physical causes for the phenomena (including relativistic time dilation, length contraction, and mass increase, the decrease in aging of any physical system making a round trip, the inertia of bodies, and why the speed of light appears constant in any reference frame). The quantum medium view explains why relativity theory works.

Consequences of the theory
Observers in different inertial reference frames (i.e. moving relative to one another) cannot agree on when observed events occur and cannot agree on where observed events occur.

Consequences of the theory
Observers in different inertial reference frames can agree on when and where observed events occur. (The observers of an event all determine the same time and the same location of the event.)

A physical system (e.g. clock) has no particular dimensions or mass or rate at which it evolves. Different observers moving at different velocities relative to the system do not agree on the dimensions, mass, or rate of evolution of the system.

A physical system (e.g. clock) has definite dimensions, mass, and rate of evolution which depend on the system's velocity through the quantum medium. Different observers moving at different velocities relative to the system can agree on the dimensions, mass, and rate of evolution of the system.

Absolute simultaneity does not exist in our universe.

As the reader reads this line, simultaneous events are occurring in all other systems throughout the cosmos.

Gravity
Gravity is a curvature of space-time according to General Relativity. The consequences include singularities and black holes into which energy and information disappear.

Gravity
Gravity is a consequence of an imbalance in the exchange of quanta of energy between and within the atoms of a body. A "gravitational force" in nature is unnecessary. This gravity does not result in singularities.

Ambiguities or paradoxes
The theory results in ambiguities or paradoxes, the Twins Paradox being the most familiar.

Ambiguities or paradoxes
None have been found to date.
The quantum medium view shows why the ambiguities or paradoxes of relativity theory occur.

Mathematical description of the theory
The mathematics of special relativity and general relativity are fairly complicated.

Mathematical description of the theory
The mathematics of the quantum medium view are comparatively simple.

* A report on student understanding of special relativity theory (Physics Education Research supplement to the American Journal of Physics, July 2001, pgs s24-s35) states, "After instruction, more than two-thirds of physics undergraduates and one-third of graduate students in physics are unable to apply the construct of a reference frame in determining whether or not two events are simultaneous."