As the rotation of the galaxy into it's 3 or 4 quadrants shows that the variables of the blue types will faze into and out of each stage as it makes a complete rotation. So it is actually the blue variables that are pushing or pulling the galaxy along and it is this that defines the presence of matter that is invisible to the eye. Meaning that dark energy is being used in the "now" moment of the blue forcing the rotation of the galaxy. It is invisible because there are many stars that are blue and many planets that have water and these seem to go together as the pull of the color blue by stars of the color blue that are pulling on the galaxy with the blue variables.
The displacement of the special blue as the blue shift in 3 or more positions as it will displace from the observer to the pre twilight and then back again as the twilight and then displace out again as the mix of the blue types of the pre twilight and the twilight as it happens.This blue shift has 3 or 4 levels where the blue shift approaches 1 that approaches 2 that approaches 3 and approaches 4.