How Do You Move a Spaceship Bigger Than a City?

A spaceship larger than a city is complete. Its inhabitants have a world to live in. How could that entire world begin a journey to another star? This science documentary follows the push from the engines through the frame, shielding and inhabited spaces of a hypothetical generation ship. A gentle acceleration can still demand an enormous force. Propellant leaves, the load changes, and the ship must keep its structure aligned while carrying the equipment that makes the journey possible. Using established physics, real spacecraft operations and experimental research, we explore chemical, nuclear thermal, electric and proposed fusion propulsion, along with the possibility of receiving a push from a distant beam. Power, cooling, propellant storage and navigation connect those ideas to the same inhabited ship. Every departure choice also leaves a question for the far end of the crossing: how will the city slow down? The giant ship is an imagined engineering scenario. Its reference mass and ideal journey are stated assumptions; advanced interstellar propulsion and braking concepts are distinguished from demonstrated technology. Illustrative spacecraft designs do not represent a built generation ship. Settle in for a calm, two-hour exploration of the physics of moving an inhabited world through space. Share your city or country, and what time it is where you are listening, in the comments. Chapters: 00:00:00 The city is complete, but departure has not begun 00:02:02 Most of the world being moved is not its passengers 00:07:56 A gentle push can occupy a century 00:16:30 Thrust has to reach every part of the world 00:27:10 The push has to change as the ship changes 00:34:43 The arrival reserve has to leave with the city 00:43:34 A powerful engine can still spend propellant too quickly 00:51:08 Saving reaction mass puts the burden on power 01:00:37 Fusion must repeat a whole engine cycle 01:11:05 Heat decides where the machinery can live 01:20:56 Saving braking propellant is an active task 01:27:56 Leaving the power plant behind creates a receiving problem 01:38:57 The ship must measure its way to a moving star 01:48:21 Arrival is a controlled transfer, not a speed record Key sources: Ideal Rocket Equation - https://www1.grc.nasa.gov/beginners-g... Buckling of Thin-Walled Circular Cylinders NASA SP-8007 Rev 2 - https://ntrs.nasa.gov/api/citations/2... Achieving Fusion Ignition - https://lmf.llnl.gov/science/achievin... Thermal Control - https://www.esa.int/Enabling_Support/...