How Do Scientists Know It's Space Expanding Not Galaxies Moving?

[LadyForCamus]

I sure wish I was smart, lol.

[Jehanne]

I sure wish I was smart, lol.

You are:

https://www.amazon.com/Most-Incomprehens...B008JRJ1VK

[Rhondazvous]

I sure wish I was smart, lol.

Perception is reality. When you perceive yourself to be a certain way, you will do.say, think and feel things to make that a reality in your life and no one can tell you otherwise. I perceive myself to be able to understand this stiff. Like I said, I may have to read something 3 or 4 times, but I do it til I understand as much as will serve my purposes.

[Alex K]

Well, not really both - we are talking about two separate empirically equivalent interpretations of the same theory. Either space can be taken to expand, or, interestingly, stuff can be thought to shrink to create the same *observed* effect.
The shrinking in this picture would not as far as I can tell cause stuff to collapse into a black hole. The shrinking is, mathematically, only the outcome, the effect of all dimensionful quantities changing: particle masses become larger thus shrinking all atoms whose extent is inverse proportional to the mass, but the gravitational constant gets smaller in this scheme, and so collapse into a black hole is prevented.

Mass is getting larger but gravity is getting smaller? Do you mean the gravity is getting weaker (which goes against my understanding of gravity vis a vis mass) or that the range of the gravitational pull is getting shorter?

Sorry that was theory slang - yes in this perspective It's getting weaker!