Are the Expanse Ships Realistic? - Science of the Expanse

recent years we've seen great leaps in human space travel from the first reusable rockets made by spacex to their new starship that looks like it was taken right out of a 1960s cartoon of future rockets since the science fiction of the 1960s seems to not be too far off the rocket science of today let's look at some modern science fiction to see what spaceships might look like in the future for shows like star trek that are set in the far future humanity has seemingly almost mastered technology with their technological mastery ship design isn't really motivated by science starships like the enterprise d seem more like luxurious cruise liners and how they're structured than ships built to let us survive space any challenges of space can simply be overcome with technology there is an apparent technological solution for every problem the most obvious case is gravity for us humans the lack of a gravitational acceleration wreaks havoc on our bodies so long trips in space need some kind of artificial gravity star trek and other science fictions often wave away the gravity problem with things like gravity plating as the name suggests these plates pull everything to them solving the gravity problem maybe one day such technology will be possible but for now it seems a bit unobtainable if not outright impossible for a more realistic ideas of what near future spaceships could look like let's look at the ships from the expanse as far as future technology goes the expanse only rarely uses it for spaceship engines these engines can generate an enormous amount of thrust and do so extremely efficiently which one day i hope we'll be able to replicate but the part i find most interesting about the ships from the expanse is how they are seemingly built around the gravity problem in larger ships like the rocinante where a crew lives all the decks are stacked on top of the engine they resemble something like a dutch canal house with a rocket attached since the engines are so efficient they can pretty much always burn at 1g while accelerating and decelerating towards a target so there is always an acceleration or artificial gravity this is a really nice solution to the gravity problem for living and traveling long distances in space no matter where the ship or crew are if they have fuel they have gravity so no health problems there this canal house idea is something i haven't really seen explored too much in science fiction before so it's pretty cool but it's not used for every ship in the expanse for smaller more nimble ships like the razorback the structure is completely different these ships are designed for speed and look more like jet fighters with the crew sitting in front and facing directly away from the engine so why is that why would the razorback have a different structure than the rossanante well the answer comes down to g-forces the effects high acceleration or g-forces have on the body is different if acts vertically aligned with your spine compared to the x horizontally perpendicular to your spine generally the main effect of acceleration is that it causes fluids like blood to pull in parts of the body on earth the acceleration due to gravity makes blood tend towards our feet but we of course have evolved to deal with this in the case of vertical accelerations like you would experience on the rossignante it's just like on the earth blood will tend towards your feet while accelerating although we can counteract the effects of 1g our circulatory system isn't cut out for dealing with a lot of g-forces forcing blood to your feet in the vertical alignment you could only really handle 5 g's before you would black out which isn't really that much but the razorback is aligned for horizontal accelerations which tends to push the blood towards your back as it turns out our circulatory system is much happier dealing with these kinds of accelerations an untrained person like myself could remain conscious for not just 5 g's but up to 20 g's for around 10 seconds that's 4 times the acceleration just from changing the direction the acceleration acts on the body this is why fighter pilots sit facing away from the engines rather than on top of them but if your concern is just survival it's possible to even survive a short burst of 46 g's of horizontal acceleration but of course you lose consciousness and black out so there really is a functional and logical reason behind the ship designs in the expanse which is fantastic but it doesn't stop there you might have also noticed that the razorback has a kind of roll cage this cage actively rotates the passengers to ensure that the acceleration is directed towards the back and feet as best as possible when turning the reason you want to direct any excess acceleration towards the feet comes down to our biology yet again as i said before our bodies can deal with acceleration to the feet reasonably well under refugees blood can still get to our brains and we can still function but what our bodies don't really expect are g-forces directing blood toward the head since the body generally wants to get blood up to the head it's really bad at stopping blood from getting to the head this means that just with two g's directed vertically to your head your brain gets overwhelmed with blood the pressure increases and you black out so if the razorback didn't have that roll cage a sharp turn in the wrong direction would lead to an instant blackout probably something you don't want happening in a tight turn i really like these ship designs unlike star trek these ships are built to face the challenges of space as we see them now and i think this will probably be what happens if humanity does become a space-faring civilization and have super efficient rockets you have vertical acceleration for ships with large crews and you have horizontal acceleration for smaller more nimble ships but there is one more class of ship in the expanse the enormous behemoth unlike other ships which are tens to maybe 100 or so meters long the behemoth is 2.5 kilometers long and 950 meters wide really earning its name the ship was intended to be a generation ship to send humanity under their own power to a nearby star system since this ship was in it for the long haul it didn't have enough fuel to rely on acceleration all the way so instead the entire outer hull can rotate to generate artificial gravity it might seem a bit ludicrous to spin an entire ship but as young anakin skywalker said spinning is a good trick spinning objects constantly feel an acceleration changing their motion around the axis of rotation to anyone standing on the inside edge of a spinning surface this acceleration feels like a force pulling them down to that surface we call this apparent force the centrifugal force this isn't really a kind of fundamental force since it's produced by your frame of reference but for all intents and purposes it would feel just like standing on the earth if it was spinning fast enough so how fast would a ship the size of the behemoth need to spin to have one g luckily physics has this pretty simple equation to tell us just that in this equation the curvy w or omega is the speed of rotation which tells us how many degrees per second the behemoth would need to spin at a is the acceleration we want so in this case 1g is equal to 9.81 meters per second squared and r is the radius of the spinning object for the behemoth this is around 470 meters plugging in the numbers shows us that the behemoth would need to spin at 8 degrees per second this gives the outer shell a speed of about 70 meters per second now none of these numbers seem unreasonable and i would even say they're achievable for us to make now provided we had the resources and construction skills to build things in space but the expanse isn't the first time we've seen spinning ships in science fiction they appear pretty frequently like discovery 1 in 2001 space odyssey and more recently the endurance from interstellar these ships are both much smaller than the behemoth so end up spinning much faster so why is the spinning design so common compared to the rocket canal house design i think it's because the canal house needs a constant 1g acceleration for it to work whereas we could build spinning ships right now though it would be technologically and mechanically challenging since the science fiction of today is often a window into the science of tomorrow it really does seem reasonable to me at least that if humanity does become space-fearing we will see these ship designs emerge from our imagination and find their place in reality since we don't have extremely efficient propulsion systems like in the expanse that can maintain a continuous 1g acceleration would be more likely to see spinning ships over the rocket canal houses in the future and who knows maybe in the distant future we will have gravity plating and warp drives like in star trek or possibly even technology that makes star trek seem unimaginative perhaps one day we'll have ships unfitted by ordinary limits on speed and size drawn by the music of cosmic harmonies to take us anywhere in space and any when ships of the imagination time will tell you

Channel: Dr. Ryan Ridden

Views: 237,131

Keywords:

Id: qA0fKJy9ewg

Length: 10min 1sec (601 seconds)

Published: Wed Feb 03 2021

Reddit Comments

[u/Ron_Sayson]

I think the key consideration towards most sci fi on television not depicting gravity with accuracy was cost. It wasn't possible given the budget of most programs.

[u/gangral]

I have a general question and my lack of physics knowledge will probably show here...

Maybe it is due to the direction the camera is moving in relation to the direction of the ship's movement but it seems like sometimes a ship is moving towards engine thrust and other times it is moving away from it. Is this due to the camera's movement in the show?

If so that makes sense. If not, it seems jarring to sometimes see a ship move towards thrust then away from it in another shot/scene.

[u/VOIPConsultant]

It should also be noted that most ships, especially Belter vessels, "cruise" at around 0.33 G. This is a "comfortable thrust" for Belters and experienced crews. Martians would be similar. I believe the Behemoth was intended to produce just over 0.4 G.