This. Constants don't come first. Experimental measurement does. It's not like constants are backed by anything. They are what they are because they're always t

This. Constants don't come first. Experimental measurement does. It's not like constants are backed by anything. They are what they are because they're always the same no matter how many times we measure them. If they changed, they wouldn't be constants. They are free to change. The one's that haven't just haven't.