What this means??: "any potential difference is the 'noise'".
What I seem to understand from your posts is that we make ground trace wider because
more current is following through it and so we try to choice a wider trace for the ground to have less RESISTANCE in the ground trace,right?
I think I need an explanation paper about the philosophy of wide trace for ground and for metallic objects in a circuit (like a metallic covered inductor inside a radio).