Is the substance of space expanding or is it really the galaxies that are expending their orbit?
Space itself is expanding. Imagine the surface of Earth. Imagine how you can walk around on the surface of Earth infinitely in all directions and never find a beginning or an end. Now imagine Earth is a balloon. Imagine someone further inflating that balloon. Earth's surface gets bigger, stuff on Earth's surface spreads further apart, the infinity in which you can travel on Earth's surface without finding any beginning or end gets bigger. It is like that with the universe, except the universe isn't a two-dimensional shape that wraps around on itself like the surface of a sphere is but is a 10-dimensional shape that wraps around on itself.
The Substance, Spacetime, is Expanding And everything is also going with it It is like you are standing in a field, that is your Galaxy You walk to the gate, there is another field, and another and so on into infinity
It's the substance of space that is expanding, yes. The galaxies float along with that. It's called the Hubble Flow.
Many scientists, perhaps most, believe that space itself is expanding.
Space is expanding, but not within or near galaxies, the local gravity is stronger than the "dark energy".
Space is expanding. The galaxies are not moving thru space. The distance between two points in space is increasing.
Space is expanding. Whether the orbits of galaxies are getting longer depends on what they are orbiting. There galaxy clusters and superclusters. The Universe has no center. The center is where you are, at the center of your own sub give universe. Space is expanding VERY slowly. I sat down and I did the math and canceled out that per mega parsec term in the Hubble constant 7 years ago. I suggest you do the same. The Hubble constant is NOT "constant." Use whatever Hubble constant you want. It is NOT a velocity. You cannot ignore that pee mega parsec term just because you do not understand what the term means.
"expending their orbit" means what?
It is the dispersion of energy that is expanding the Universe.