What is the actual evidence that space expands and galaxies stay put?
We have no independent evidence for this other than on the cosmological scale. General relativity has succeeded in predicting/anticipating a number of crucial phenomena over the years: The correct amount of the deflection of light by the Sun; The precession of the perihelion of Mercury; The gravitational red shift of light. Astronomical observations have also confirmed, through studies of the Hulse-Taylor Pulsar that gravitational radiation exists as predicted by general relativity. Also, the phenomenon of gravitational lensing predicted by general relativity agrees with the images of an increasing number of distant galaxies. No one has ever seen space stretch in the way predicted by general relativity. This is not a phenomenon that can ever be under human control in a laboratory. However, if we tried to use other explanations for the red shifts we see from distant objects, you would end up with measurable consequences that are even harder to accept than the dilation of space. Example,
