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So I'm trying to write a simple, accessible explainer on artificial gravity. Does the below make sense to you?

In The Expanse, the colonisation of the solar system was made possible by the Epstein drive – an advanced rocket technology. The Epstein drive is fiction, but the physics around it are real. Like, in space, there’s no gravity, which sucks – because your muscles waste away, your drinks spill everywhere, and the VFX budget gets too big. A lot of sci fi shows get around this by inventing some magic ‘gravity plating’. But The Expanse is more realistic, because its spaceships make artificial gravity from acceleration. It’s like how accelerating a car pushes you back in your seat.

By accelerating constantly, a spaceship can use that pushback as gravity, pulling you down towards the thruster.

The faster you accelerate, the stronger the gravity – so flying at one g is Earth gravity, while two g is double Earth gravity, making you weigh twice as much. When you’re in a hurry, or in combat, ships might fly at five or six gs. The Expanse has a drug called the juice which helps people survive this – but too much g force will kill you. Usually an Epstein ship will accelerate at a comfortable half or third of g. They’ll constantly accelerate for the first half of the trip, then flip around and thrust in the other direction, to decelerate for the rest of the trip.

That way the ship slows to a stop at the destination, keeping thrust gravity the whole time. This is an actually plausible way to fly a spaceship – if only we had rockets as good as Epstein’s.

But sometimes you want gravity without having to constantly accelerate somewhere. So another method is to rotate an object so the centrifugal force pushes you outwards. 

It’s like the Gravitron, that spinning carnival ride that pushes you outwards. Spin up a space station, and that force can be your gravity – like in 2001: A Space Odyssey. In The Expanse, they don’t just spin up ring stations. They take planetoids like Ceres that are too small to have their own gravity, and they artificially “spin up” the whole rock to give it centrifugal force. The spin gravity pushes outwards, so people walk around on the inside of Ceres, underground. This spin gravity in Ceres and Eros is a third as strong as Earth’s gravity – which what gives the Belters their tall, thin bodies. The people and cultures of The Expanse are shaped by real-world physics.

--- So does that make sense? The images are just placeholders - wanna get the wording right before we make proper animations.

In any case, this first Expanse video is looking sweet – should be out later this week. The second Expanse video about Book 1+Season 1 is also coming along. And just quietly, we might be getting to speak directly with Expanse authors Dan and Ty soon...

On the ASOIAF front, we're planning a much-requested video about the far east of the world of ice and fire – using artwork from the Unseen Westeros exhibition.

Have also made a final(?) version of the new ASX logo:

So good things are coming!

Cheers

ASX

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Comments

Alice Cottrell

Years ago, local bookstore employees (who really knew their customers) handed me Leviathan Wakes, Game of Thrones, and other books too numerous to name, saying "You'll like this!" I've never regretted any of those purchases. And I'm so happy to have found Shift to help us make sense of it all. I'm really looking forward to your Expanse vids. Thanks for doing it!

AdamLee Nesvold

The explanation makes perfect sense! Thanks!

Ruggero

The explanation is good! A couple of gotchas that may potentially be too much: 1) It's not technically true that in space there's no gravity. Gravity from the Sun, for example, is always there, but you're moving at the same speed as anything else next to you around the Sun, so you have no relative acceleration towards them. 2) An always accelerating and always decelerating ship makes sense but it's also a lot of fuel. You go faster, but at some expEnse. For example, Elon Musk's SpaceX mission to the Mars orbit with the Starman and the Tesla, accelerated only for a few minutes, but that was enough to put the ship in an orbit that will cross the Mars orbit (it would have taken more energy eventually to stay in the Mars orbit and they won't do it, but they could if they had the fuel there). There is even a mathematical proof that in theory you can go from any Lagrangian point to any other Lagrangian point of the Solar System without much energy, it'll just take you a very long time (but Lagrangian points are complicated). 3) If you make an asteroid rotate, you need to rotate more than its gravity will pull you in. This is similar to Earth at the equator where gravity is a bit weaker because of the rotation, but Earth's gravity is so much that you need to rotate really fast for Earth to have the same effect - that's why you want to do this on asteroid and not on a planet with things on the surface. 4) It might be fun to refer to some of the crazy experiments people have done to see how many g's humans can survive. Awesome job as always! I like this temp graphics, they remind me of the old game of thrones silhouettes which had some clarity and brought some gravitas. Bring some of them back! :-)

Kenny Arnold

It makes sense enough, although there is still gravity in space. Astronauts on the ISS appear to be in 0 G because the velocity at which they are traveling equals the speed at which the earth curves away from them, thus making them appear weightless.

Hank S

Very well written and thought-out explanation of artificial gravity. Looking forward to the new video. If you want to get even more technical about it, you could talk about the spin gravity resulting from an object’s inertia that makes it want to travel in a straight line at a constant speed. A number of commenters have also mentioned how an asteroid like Ceres would likely fly apart if spun up to a higher rotational speed. But something that’s really cool is the Coriolis force evident when Miller tries to pour a drink. The liquid move sideways and down into the glass. Here is a link to an article about it : <a href="https://www.forbes.com/sites/chadorzel/2016/01/19/the-expanse-and-gravity-beyond-the-equivalence-principle/" rel="nofollow noopener" target="_blank">https://www.forbes.com/sites/chadorzel/2016/01/19/the-expanse-and-gravity-beyond-the-equivalence-principle/</a>

Kelly Theobald

Wow there’s so much intelligent talk here...meanwhile we’re arguing about emus and otters in the Squwad 😂 the third schwiftpocalypse is happening by the way. Fun times. It makes sense. The only thing that tripped me up was why they had to flip and decelerate halfway through; cuz you wouldn’t do that in a car—then I realized that in a car, you’re not constantly accelerating, you’re just maintaining speed, and then it clicked. But it took a second.

some punk

Could you change out the car metaphor for a rollercoaster? I associated the feeling of pulling Gs with rollercoasters more than cars. Also I immediately thought of the Gravitron, so that kind of stays with the carnival theme. Overall though very nice explanation! (I would also like to second the mention that there technically is gravity in space -- NASA has named it microgravity.) (That also makes me question (as someone who doesn't know this series) about whether the people closest to the rockets would experience higher Gs than people further from the rockets -- given that one experiences lower Gs that farther one gets from Earth. I don't know if that plays into anything. I suppose simplified explanations always make me go, OOOH EXPLAIN MOOOORE :D)

Alex Felix

Don't you think you should make the spacing for the A and the L the same as the spacing in Shift?