5 0 0Actions Report Solution *** Spoiler - click to reveal ***Once you go to 1931 looking for Doc, go to the Police Station and talk to Doc. Doc will wish to hear his own voice. To do this, use the recorder on Doc's younger self by selecting the recorder and using it on Doc's younger self.Come back to the Police Station and play back the recording to Doc (the one in jail). He'll explain what the recording is (The Hamiltonian Operator).Go back to young Doc and give him the answer... and follow the rest. Leave a comment