The Atlantic has the article
My Grandfather Thought He Solved a Cosmic Mystery: His career as an eminent physicist was derailed by an obsession. Was he a genius or a crackpot?

In essence, what he thought he’d found was a way in which probabilities arose naturally, a way in which they could be derived from the basic laws of the physical world rather than deduced from experiments. And he thought this should apply in the quantum world as well. It was both as simple, and as grandiose, as that. All the other papers, down through the years, involve elaborations of this main idea.

This paragraph is as tantalizing close as the author gets to explaining the idea.

This makes me think some more about a tantalizing paradox that physicists are talking about these days. That is called quantum entanglement. Two particles are entangled in such a way that the two have opposite values of a physical quantity. You don’t know (can’t know) the value that either particle has until you measure one particle. As soon as you know the value one particle has, you know the value that the other particle must have. If you don’t make the measurement until the two particles are separated by large distances, it leads to the question of how the remote particle can instantly take on a known value when you make a mearuremment on the particle you have close access to. The special theory of relativity tells you that no particle, and no information, can travel faster than the speed of light. Quantum mechanics tells you that the answer to what value each particle has doesn’t even exist when the particles were separated and sent on their different paths. It does not seem possible that both of these physical laws can both be right, and yet the entangled particles have been shown by experiment to behave the way I described. It seems obvious that something we can’t explain is exactly what is happening. I have no idea what the answer is, but it is just interesting to think of what has to happen for someone to figure it out.

Maybe Francis Perey had the kind of insight that will be needed.