Here the attention of the research workers is primarily....

“ Here the attention of the research workers is primarily directed to the problem of reconciling the claims of the special relativity theory with those of the quantum theory. The extraordinary advances made in this field by Dirac ... leave open the question whether it will be possible to satisfy the claims of the two theories without at the same time determining the Sommerfeld fine-structure constant. ”

Werner Heisenberg

From : Physics and Philosophy: The Revolution in Modern Science