Picture a 58-year-old Danish theoretical physicist lying on a mattress in the bomb bay of an unarmed Mosquito bomber crossing the freezing North Sea, passing out from oxygen starvation because his head is too large for the standard-issue flight helmet. That is Niels Bohr in 1943, on his way to change the course of the war. This episode is a deep dive into his physics, his politics, and the philosophy his head was big enough to hold.

We trace the science: the 1913 Bohr model that introduced quantum jumps to atomic structure, the years of dialogue (and famous disagreement) with Einstein, and the principle of complementarity that defined the Copenhagen interpretation. Wave or particle? Bohr argued the question is malformed, the choice depends on the experiment, and the wave is just the mathematical tool we use to grasp interactions we c ...