Abstract

The theory of relativity is an ether-less theory. The reason for this is that aberration of starlight has been considered to rule out the entrained ether, and Michelson-Morley's measurements (MMX) are interpreted as refuting the absolute ether. Errors are found in both these conclusions and entrained, as well as absolute, ethers are both possible. It is also demonstrated that a transverse ether-wind can not cause wave-front bending, and that Stokes' 'correction' to Michelson's prediction was without motivation. The existence of an ether has been demonstrated very clearly by the Sagnac effect for translational motion. It is therefore important to find out if the ether is entrained or absolute. The Sagnac effect IS the ether-wind and can help us to find the answer. By using interferometry, instead of synchronized clocks, we can reach higher precision. Experiencies from GPS (global positioning system) seems to indicate that time dilation and clock bias must be abolished.