Ships in movies and tv series come in all kind of styles. Especially when you get inside you will find all levels of comfortability, from industrial dark to the shiny white hotel style. What would spaceships really look like on the inside?
First of all spaceship interior design has to be functional. Nobody cares if it looks cool or feels comfortable when it doesn’t do the job. Ships will most likely not be almost hollow shells with dozens of decks and hundreds of cabins like on cruise ships. Only a fraction of the hull will be accessible by the crew via hallways, tunnels and elevators, the rest will most likely only be connected by very low service shafts, wide enough for drones and robots to get through. Crew members can use some of these shafts in an emergency, but it will be very tiresome and slow. The reason is that the internal structure of a spaceship has to compensate a lot of stress during acceleration, deceleration and maneuvers. And a lot of space will be taken up by machinery, pipes and cables, storage tanks, battery banks and much more. You would not build rooms and halls and than place these items inside, instead you would incorporate those components into the interior hull as much as possible without wasting space and mass. Every gram of mass in space matters. Spaceships will be pretty dense and not as spacy and hollow as marine vessels. Imagine the confined spaces of a submarine.
The interior design shown on the left is a typical example and could from any pc game or sci-fi movie. Design and looks count more than functionality and safety here. Multiple lighting (even in the floor) provides enough light but the walkway looks pretty unsafe with a high potential for accidents.
In spaceships a man sized hallway needs a safe and plain underground, some holds and bars on the walls and ceilings (you will travel under zero-g often) and no obstacles with sharp corners that crew can slam into. Also those glowing glass cells look as fanastic (some sort of energy cells maybe) as they look fragile. A single screwdriver or tongs spinning through this section under zero-g could cause tremendous hazard.
The design on the right shows another problem found in many horror sci-fi settings – it’s just too dark. As long as un-augmented humans make up your ship crew, you will have to provide very good lighting to ensure people can do their job and don’t endanger themselves. Lighting would not be on constantly but most likely switch on and off automatically (triggered by motion and heat sensors, voice command or similar). You would not wnat to waste energy on lighting, but you definitely would not want to cause any health risks to your crew (you can’t replace them out there). Robots and drones would be able to move and work in complete darkness or dim light, but there should be accident prevention by design when they are crossing humans aboard the ship.
The often seen dim red emergency lighting is not realistic. As long as the main energy source of your ship didn’t shut down, you have plenty of energy to provide good lighting. If your reactor goes down a spaceship will switch to emergency batteries to keep up life support (air, temperature, pressure, lighting). As light is only required for limited periods of time and in certain places during an emergency (your crew quarters will probably get dark or at least only receive 30% of normal lighting) there is a good chance that the crew will not have to fix the broken systems in near darkness but under normal lighting conditions. They will probably be supported by mobile light sources and drones for a while.
As all systems aboard a ship should be redundant, cutting a single cable will not turn off the lighting in an entire section. A professional will find a way to cut off all light willingly, but it is unlikely that this will happen as soon as a ship takes a hit. All the dramatic flickering and dimming of the light seen on some series and movies is not realistic. You won’t see imploding bulbs on spaceships or flickering neon lamps.
Habitats and the bridge itself will be much more comfortable, though still practical. People can live in very confined spaces for a while, but if you are planning to make a system trip over several months you should take care that the crew is not getting claustrophobic. Military ships and cargo haulers will probably have a simpler and more practical interior design while luxury ships could look like hotels on the inside. Yet, the laws of space travel deny 15m high halls, pools with open water or other stuff you might find on marine luxury ships.
So hallways and crew rooms will probably not be as confined as on a submarine but also not as spacious as depicted in flicks like Star Wars. Walls will not be covered with shiny plastic sheets (they won’t stay shiny for long) or glass elements (glass is just too heavy) for miles, simple removable plastic covers in dull grey will be more likely, allowing access to systems/storage in the walls. Hallways and cargo holds will allow special transport vehicles and robots to move stuff around, but the ceiling height will be rather low. Loading and unloading spaceships like ships on Earth would take forever. It is more likely that whole cargo sections will be removable in one piece while docked. They could use their own small apogee motors and actually fly themselves out of the ship and into the station. You would not want to wait until one million liters of fluid hydrogen have been pumped from the cargo tanks, you more likely simply remove the whole tank array and replace it with another one.
Spaceship crews still would have to struggle with mental and organic problems connected to living in a small box.