[cc-d]

>Or, more precisely, IQ is heavily correlated with the ability to succeed at taking IQ tests.

...and succeeding at taking IQ tests is also predictive of an individual's potential to succeed at, using the Feynman example, physics.

Lets say you were to gather two pools of individuals, one pool with IQ test results of 2 standard deviations below, the other with results of 2 standard deviations above, and provide them with the necessary materials and instruction to understand physics 101. Incentivize the participants by offering a $2000 cash reward for demonstrating the knowledge they were tasked with learning, lets say by answering X questions presented to them in whichever format would be optimal for their success.

How many from group -2 SDs do you think would receive the $2000, compared to group +2 SDs? -1 SDs compared to +1 SDs?

The choice of physics was arbitrary as well. You could assign almost any field of study, and you would still get almost identical results in performance.