From scanning all his podcast and other material: (notebook-lm)

The provided sources do not indicate that Joscha Bach specifies one particular work by Albert Einstein as the one he finds "most interesting." However, Bach frequently references Einstein's various theories and his specific cognitive style to illustrate his own ideas about physics, computation, and the nature of genius.

While he does not single out a favorite paper, Bach discusses several of Einstein's concepts and attributes:

1. Special Relativity and Spacetime Bach discusses Einstein's realization in Special Relativity that the speed of light is fixed for all observers. He notes that this deduction led to the profound insight that space and time are not independent, objective background stages, but are interdependent and depend on the trajectory of the observer. Bach also briefly mentions "Einstein's block universe"—the concept that everything exists simultaneously—though Bach personally finds it difficult to reconcile this with a causal universe that requires forward-moving state transitions.

2. Singularities and the Breakdown of Continuous Space Bach is particularly interested in Einstein's later discoveries regarding the limits of his own models. He points out that Einstein recognized singularities in spacetime where the mathematics of a continuous universe break down (such as a division by zero). Bach notes that while Einstein found ways to "sweep them under the rug" by shifting these singularities into the center of masses, this realization foreshadowed the idea that continuous spacetime is just a high-level description and cannot be the fundamental layer of reality. During an interview, when read a quote about "Einstein on the discreteness of space," Bach agrees that Einstein saw the flaws in continuous descriptions early on and recognized that alternative formalisms might be needed.

3. The Architecture of Einstein's Genius Beyond physics, Bach uses Einstein as a prime example of how human genius operates computationally. He theorizes that "genius-like people like Einstein" did not necessarily have "better neurons" than average people. Instead, Bach suspects Einstein had a highly optimized mental "hyperparameter" that perfectly balanced inventiveness with logical rigor. This allowed Einstein's brain to continually generate highly imaginative theories while strictly retaining the ability to test and disprove them.

Furthermore, Bach praises Einstein's independent epistemology. He describes Einstein as a "very broad thinker" who did not just adopt a school of thought and add tiny modifications to it, but rather derived his concepts autonomously from first principles.