Spaceships and Hollywood

Spock and Kirk
First officer Spock (left) and Captain Kirk on the Starship Enterprise didn’t float inside their spaceship because of “artificial gravity.”

Spoiler alert – in the future there never will be artificial gravity – astronauts won’t be able to walk around in spaceships.

In the movies most spaceships like the Starship Enterprise employ a convenient technology they call “artificial gravity” to overcome this weightlessness problem. In a few movies they even rotate parts of the ship, though the part of the ship that rotates often has no relevance to the part of the space ship people are walking around in.

No matter. Walking around is a convenient way to avoid a big budget.

Battle-Spaceship - gravity inside will not exist
This battle-spaceship shows not even an attempt to justify how people inside seem to have no problem walking around.

Weightlessness is a pesky little problem and we’ve become comfortable accepting that on spaceships of the future you’ll be solidly on the floor. Venture outside to fix anything and you’ll be weightless maybe (unless you use something they call “gravity boots”) but inside, put something on a table and it stays on the table. People won’t be weightless in spaceships in the future.

That’s why they call this stuff science fiction. There won’t be any artificial gravity and to the dismay of Kirk and Spock a spaceship that looks like their’s will have weightless people inside.

Von Braun Spacewheel
The Von Braun Spacewheel is the only design occupants could have “artificial gravity” via centripetal acceleration.

Another design, a real design, for a spaceship that would actually have “artificial gravity” is called the Von Braun spacewheel, and envisioned in movies wanting more realism. The Von Braun spacewheel looks like this contraption. Of course, it spins and as it does the occupants inside experience centripetal acceleration, also sometimes known as artificial gravity.

So why doesn’t NASA build one of these?

Well, along comes the real world, pushing Hollywood right outta there.

  1. They don’t have the lifting power to get all the parts up there. It’s doubtful the Falcon-heavy will be utilized for such a project.
  2. Assembly and then pressuring it inside are formidable obstacles. This is not impossible, but beyond available budgets.
  3. Zero gravity laboratories, like the present International Space Station have taught us that research in microgravity environments is valuable.
  4. With exercise, astronauts do just fine, so why bother?

Alas, we may send people to Mars one day, but those poor ol’ chaps will be weightless all the way, and exercise like they do on the ISS.

Space Debris – A Dodging Problem

This is a no frill video (no audio) produced by scientists, to depict just how much junk “litter” we have floating around up in space, some of it going 35,000 miles per hour.

Just something to think about.

Elon Musk’s Automobile to be put in Orbit around Mars


This rather large SpaceX rocket is called the Falcon Heavy. Inside is the automobile below, which SpaceX hopes to launch in orbit around Mars with a flight schedule February 6, 2018 (assuming it doesn’t blow up on the launchpad).

You just can’t make this stuff up. The automobile, which belongs to the founder of SpaceX Elon Musk, is a Tesla Roadster. If successful, the automobile could stay in orbit around Mars for a few billion years. The car will just be let go to float on it’s own ’round and ’round Mars.

I guess that’s in case you ever need to catch a ride to orbit Mars!

If two ships are travelling side be side at some major fraction of the speed of light (e.g. 90%) and are, say, 100 yards apart, would they be able to see each other out the portholes?

Great question, and you see, that’s what we mean when we say everything is relative. Your “speed” is always relative to something else. If you don’t compare it to something else, you might as well be standing still.

Relative to you, the other spaceship is standing still. You are both just floating there while Earth quickly moves away from you.

If you were going 90% the speed of light relative to your launching site on Earth, then if you looked back at Earth through a telescope you’d see them all aging very quickly, but to you and your neighboring spaceship, you’d both not experience any personal change. You’d be able to see the other ship and vice versa quite normally.

In fact, if you took a flashlight and pointed it straight ahead in the direction of your travel, even though you were going 90% the speed of light relative to Earth, the beam of light would leave your flashlight at the speed of light relative to you. That’s only possible because time has slowed down for you, making light always look like it’s going light speed. You will not notice any change personally.

On Earth, people looking at you in a telescope would see you were moving and aging very slowly, and although the light of your flashlight would not appear to be going much faster than your spaceship, because your time has slowed down, you see it going out at the speed of light and people on Earth are moving slowly.

Consider this. Here you stand or sit. But the earth is spinning at about 1000 mph at the equator. We are also going around the sun at about 67,000 mph and orbiting the galactic center of the Milky Way galaxy at about 514,000 mph, and our galaxy is approaching the Andromeda Galaxy at about 250,000 mph. So you are not standing or sitting still at all! You are moving very fast right now, but when you shine a flashlight in all directions the beam leaves your flashlight at the speed of light relative to you and your sense of time.

The same happens to you and your friend in the nearby spaceship. You can look out the porthole, see him, and wave and he can see you and wave back as if both your ships were stationary in space and just floating next to each other. It’s all relative.

How close to a black hole (with 10 solar masses) must you be before time for you is dilated significantly, compared to your crew’s, 1 million km out?

A thought experiment: I was imagining a scenario where a spaceship tethered their compatriot and lowered him near the event horizon & then pulled him back towards the spaceship before being pulled into the black hole. Wouldn’t time go by quicker for him? Would there be a discrepancy in their ages?

Not very far away from the event-horizon. Here’s a scenario to contemplate:

They would lower him on a tether and his shuttle craft would appear to freeze in time. Pulling back would bring him back with great difficulty and very slowly. He would appear to be stuck. If they continued to pull, it would take decades to get him back.

Inside the shuttle craft, he gets lowered toward the event horizon, stays a few minutes, then gets pulled back up.

When he gets back his crew on the main space craft has grown very old, and as far as he was concerned, he was there only a few minutes. As far as they were concerned, he was down there for decades. This is the correct answer.