This thought experiment has been bugging me for a very long time - I'm hoping someone can help me understand it. Premise: - Simple DC electrical circuit consisting of a battery, wire, light bulb, and another wire to complete the circuit. - Each wire has a length of 1 light-year (yes, very long). - The wires have zero resistance. - I'm assuming that electricity travels at the speed of light in the wires. Question: From when the battery is connected to the circuit, how long will it take for the bulb to illuminate? I keep thinking the answer must be either 1 year or 2 years. But both answers cause me problems, so expect follow up questions :) Thanks!