This step relies always on some physical intuition which is not easy to quantify.
He was mathematically brilliant and had the most amazing physical intuition.
It was the precision of his eye and hand that betrayed him, not his physical intuition.
"He tries to see farther over the horizon than most people by way of his physical intuition."
Once this split is made, we can easily apply physical intuition to the problem.
So one has to use that delicate substance known as physical intuition.
Nevertheless, physical intuition needs to be examined critically in the real case, before one jumps to false conclusions.
Bohr used his physical intuition to decide which quantities were best to quantize.
His work is marked by a penetrating physical intuition combined with a methodical and mathematical line of thought.
"I was blessed with a tremendous physical intuition," he said.