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If you haven't read the books or watched the show, The Expanse does a great job at working in a world with realistic physics. A lot of combat takes place from

If you haven't read the books or watched the show, The Expanse does a great job at working in a world with realistic physics. A lot of combat takes place from extremely far distances, using telescopes, rail guns and missiles, and it can sometimes take days for a missile to reach the target (the TV series doesn't play this up as much though, for obvious reasons). When there is closer combat battles, they are constrained by the G forces humans can tolerate, wear full helmets and de-pressurize their ships, so when the inevitable shots do go through (usually in and out the other side) it's not catastrophic. There are no force shields, magic gravity generators, lasers (well, except used for point-to-point communications). I found it to be very refreshing mainstream sci-fi. One warning: after watching The Expanse, the battles in things like Star Wars, Star Trek or Battlestar just look ridiculous by comparison - even with that technology they'd never fight like that.

garmaine 6y ago
Not to take away from your post, because I largely agree, but the Epstein drive might as well be magic. In no realistic universe are there large battle cruisers zipping around the solar system under constant 1G (or even Mars’ third-G) acceleration for months at a time. But aside from that and the whole aliens technology thing the plot revolves around, it is very realistic. They certainly get a lot closer than anybody else.
- saberdancer 6y ago
  Physics is realistic, engineering not so much? :)
- ivalm 6y ago
  I am not sure how unreasonable is prolonged 1g. You can’t do it for months (since if it’s all in one direction you will start getting relativistic, one month of 1g gets you to almost 0.1c) but at medium speeds it isn’t too bad. Suppose you have a megaton ship moving at 100km/s with 10 m/s^2 acceleration Power = m v a = 1e9 x 1e5 x 1e1 = 1e15 W While petawatt is a lot, a megaton ship is also huge. Epstein drive is a fusion drive of sort, the easiest aneutronic reaction would be B+p -> C + 16 MeV So 2.5e-12 Joules per fusion Which means you need to burn 1e15 J/s /(2.5e-12 J/atom)*(2e-26 kg/atom) = 8 kg/s Suppose your engine runs at 10% efficiency, it means you are powering a megaton ship on less than a 100kg/s of material. So if your megaton ship starts as 10% fuel you have ~115 days of continuous thrust.
  - garmaine 6y ago
    You're assuming way too high an efficiency. A real fusion rocket would fall far, far short of that. 2% efficiency would be generous. Googling fusion rocket mass efficiencies shows estimates of around 1 ton / MW, so you're not too far from the mark. But that gets to what the Epstein drive basically is, in-universe: a 100% efficient fusion drive. No physical laws being broken, technically, just the nuclear rocket equivalent of a perpetual motion machine. They do in fact go around at 1G (or 1/3 G) thrust for months at a time in the books and show, accelerating full speed for half the trip, then turn around and decelerate for the other half, for trips to/from the outer solar system. In the inner solar system it's only a few days to weeks to get anywhere. This lets them operate in artificial gravity without spinning the spacecraft, which is convenient for filming (although it's in the source novels too).
    - ivalm 6y ago
      My point is that even if it is 10% efficient, which is only 5 times more than your estimate， you have 4 months. Even if it is 2% efficient, you get ALMOST a month. Re: accelerating for many months at 1G is definitely bad physics, not only are you relativistic, you start getting into the kind of speeds where a minor meteorites will wipeout your ship. 1 gram meteorite with a relative velocity of 0.5c has 1.4e13 J of kinetic energy = 3.5 kton of TNT, so a small nuke.
      - garmaine 6y ago
        yeah the speed they travel through the inner solar system is pretty ludicrous, especially when you consider how much space junk is generated by all that activity.
    - TwoBit 6y ago
      I think comparing future technologies with today's Googke searches is unrealistic.
      - garmaine 6y ago
        Exploratory engineering does put firm limits on future capabilities. There are many possible steam engine designs, and I'm sure those we use today were unimagined in the 1820's. Yet none are more efficient than an ideal Carnot steam engine. The same principle applies here.
- magicalhippo 6y ago
  > the Epstein drive might as well be magic For me, good sci-fi does just that, ie limit the magic to one thing or technology, and use that to explore something interesting. Same with Altered Carbon. What would happen to society if we could swap bodies but keep our minds? That one piece of technology ("the stack") is magic, but from it follows lots of interesting exploration of the possible impacts on society etc. What I hate is when they try to explain the magic. Don't do that. It never works. Just assume it's there, someone discovered it, invented it whatever.
  - TeMPOraL 6y ago
    But you have to try and explain the magic. If you didn't, your universe would break. Depending on the postulated mechanisms of action, the principles behind the magical invention will have vastly different impact on societies. For example, it matters how is it the ships can casually sustain a 1G burn for a week at a time. If it's efficient nuclear fusion, then the ships get bulky, energy is no longer a problem in the society at large, and the exhaust of said engine is a weapon of mass destruction. If it's subspace field shenanigans, then aforementioned impacts don't necessarily apply, but there is an open question of how small such subspace field combobulators can get, and what else could you do with them. Technologies have second-order consequences, and societies shape to accommodate them. Half the fun of science fiction is in exploring those. If you just call it magic and define it by a set of arbitrary rules, then your fictional universe will look shallow and inconsistent.
    - krapp 6y ago
      >But you have to try and explain the magic. If you didn't, your universe would break. Depending on the postulated mechanisms of action, the principles behind the magical invention will have vastly different impact on societies. Star Trek goes into intricate detail trying to explain its warp drives and comes off looking far less grounded than the vast majority of sci-fi properties with FTL or jumpgates or whatnot that either don't explain anything, or just offer a few details. Whether it breaks your universe depends on the themes you're trying to explore, such as the nth order effects of radical technologies on society. Most of the time, the story isn't about the technology (in the same way that Westerns aren't always about animal husbandry and gun manufacturing), and it's sufficient that you push some buttons, pull a lever and spaceship go brrr.
sxp 6y ago
The Expanse gives the illusion of real physics, but the actual physics are pretty fake. None of the orbits of the planets or the space ships follow realistic path. One of the authors mentioned that they didn't calculate the positions of the planets or the trajectories between them. So the Expanse isn't as realistic as 2001 or the Martian where the orbital mechanics play a key role in the story. This may seem like nitpicking, but if you want to discuss the politics of space, the distance between planets and the travel time between space polities becomes a critical aspect of politics. The Expanse is in an uncanny valley of hard sci-fi. It's not as realistic as Kerbal Space Program but use technology as a magical way to explore speculative scenarios like Star Trek did. And a core part of the first arc is a stealth ship which is not hard sci-fi at the Expanse's tech level: http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth http://www.projectrho.com/public_html/rocket/spacewardetect....
- herodoturtle 6y ago
  Well said. I recently got into a "the Expanse is not hard sci-fi" discussion, and the politics of space (between distant planets) was an interesting angle we hadn't considered.
- feral 6y ago
  Why can there not be stealth in space? The link you gave doesn't seem to have any arguments. Not saying you're wrong, just curious. Some simple arguments that it's not a ridiculous question: There is stealth on earth - paint and geometry that reduces EM signature. Why couldn't there be something similar in space? It's not like it's super easy to detect everything in space today either - we have big telescopes but regularly miss small asteroids?
  - gambiting 6y ago
    Because your spaceship has to generate heat for various systems - at the very least, to keep its occupants alive. That heat, unlike on Earth, really stands out against the cold of space. You can hide the emissions of many vehicles on Earth, because Earth and its atmosphere is pretty warm compared to space in the first place. But in space all you need to do is look for heat signatures(infrared and others) and you will spot any vessel immediately. Some Sci-Fi has tried addressing it with plausible ideas - like for instance dumping all heat into shielded internal tanks, which have to eventually be vented(so that stealth cannot be infinite because you run out of heat storage capacity on board).
7373737373 6y ago
That's what I like about For All Mankind too, though it seems we have to wait for the second season for any real action to occur.
- saberdancer 6y ago
  I found For All Mankind really refreshing and enjoyable. One of my favorites is the fact they didn't shy away from prejudices of the time and they didn't make a series where guys from 60s have fully modern views.
simonh 6y ago
I don't really mind the Epstein Drive and really appreciate the effort to portray a decent stab at realism. It's very refreshing. The one thing that bugs me a bit is the way they conceptually represent the solar system in the show. If you follow the way the situation is represented you essentially have Earth on one side of the solar system, Mars in the middle and the asteroid field on the other side. That seems to be how the strategic situation is presented. To get from the asteroid field you essentially have to go past Mars, which is closer to the asteroids. If you think about the actual layout of the solar system this makes no sense, in reality Earth is about in the middle and any given asteroid is closer to the Earth at any given time than it is to half the rest of the belt. Again, it's fine. There's no way to capture the real dynamics of the solar system in the story without hopelessly bogging everything down, and for the purposes of the show the simplified model works fine. I suppose you could argue that during the period of the show by chance most of the main asteroids and Mars happen to be lined up on roughly the same side of the solar system as Jupiter, and then it basically works. It's just a bit of a fudge.
- jusssi 6y ago
  The strategy representation could also be rationalized as the Mars actively positioning their forces near most efficient transfer routes between points of interest. There seems to be relatively few places in the Belt and outside where anyone would want to go to, and guarding empty space where you'd expect no one to pass wouldn't make much sense. So ships transiting from Earth to the Belt would be going through Mars' solar orbit doughnut-of-influence. This of course ignores that with the Epstein drive magic, one could always trade travel time for going around ie. off-plane. There's plenty of, well, space for that. (Edit: according to the no-stealth-in-space link in a sibling post, one would be seen doing that, and likely get chased for it as being suspicious).
- rob74 6y ago
  Ah, the Epstein Drive, invented by Solomon Epstein, the Zefram Cochrane of The Expanse - seems like an unfortunate naming in retrospect, but I guess the novels were published a few years before Jeffrey Epstein became notorious...
hef19898 6y ago
The Expanse did a great job showing space battles on screen with a rather approriate distance. Star Wars and others, and I am a full blown Star Wars freak, did a good job with space battles. After the Expaense, it became little bit ridiculous, so. I resembles the problem films like Top Gun have with modern aerial combat. Already in that case, distances are so great that on-screen, the viewer is seeing nothing. For space battle, the enemy would maybe show as a small blip, if at all on screen. Especially with all the hyper advanced tech from Star Wars and Star Trek. This is also the reason why I igonre any stab at estimating weapon ranges based on on-screen scenes.
MaxBarraclough 6y ago
> even with that technology they'd never fight like that This applies to just about all fictional combat, no matter the setting.
lmilcin 6y ago
The Expanse is pretty bad at engagements or physics. They only look superficially well and that because other movies are completely unrealistic and space battles are there just to fill the screen with action and graphics effects, hopefully as background for the real narrative. Also, if you are looking for any kind of realism in Star Trek battles you are completely missing what the series is about. I like SF and I love Star Trek just as I love reading hard science fiction. Just don't mistake the two, because looking for realism in Star Trek would be like trying to do linguistic analysis on magical incantations in fantasy.
setr 6y ago
If you want a space opera with more realistic setups/politics/internal logic, Legend of the Galactic Heroes is top tier stuff

garmaine 6y ago

Not to take away from your post, because I largely agree, but the Epstein drive might as well be magic. In no realistic universe are there large battle cruisers zipping around the solar system under constant 1G (or even Mars’ third-G) acceleration for months at a time. But aside from that and the whole aliens technology thing the plot revolves around, it is very realistic. They certainly get a lot closer than anybody else.

saberdancer 6y ago
Physics is realistic, engineering not so much? :)
ivalm 6y ago
I am not sure how unreasonable is prolonged 1g. You can’t do it for months (since if it’s all in one direction you will start getting relativistic, one month of 1g gets you to almost 0.1c) but at medium speeds it isn’t too bad. Suppose you have a megaton ship moving at 100km/s with 10 m/s^2 acceleration Power = m v a = 1e9 x 1e5 x 1e1 = 1e15 W While petawatt is a lot, a megaton ship is also huge. Epstein drive is a fusion drive of sort, the easiest aneutronic reaction would be B+p -> C + 16 MeV So 2.5e-12 Joules per fusion Which means you need to burn 1e15 J/s /(2.5e-12 J/atom)*(2e-26 kg/atom) = 8 kg/s Suppose your engine runs at 10% efficiency, it means you are powering a megaton ship on less than a 100kg/s of material. So if your megaton ship starts as 10% fuel you have ~115 days of continuous thrust.
- garmaine 6y ago
  You're assuming way too high an efficiency. A real fusion rocket would fall far, far short of that. 2% efficiency would be generous. Googling fusion rocket mass efficiencies shows estimates of around 1 ton / MW, so you're not too far from the mark. But that gets to what the Epstein drive basically is, in-universe: a 100% efficient fusion drive. No physical laws being broken, technically, just the nuclear rocket equivalent of a perpetual motion machine. They do in fact go around at 1G (or 1/3 G) thrust for months at a time in the books and show, accelerating full speed for half the trip, then turn around and decelerate for the other half, for trips to/from the outer solar system. In the inner solar system it's only a few days to weeks to get anywhere. This lets them operate in artificial gravity without spinning the spacecraft, which is convenient for filming (although it's in the source novels too).
  - ivalm 6y ago
    My point is that even if it is 10% efficient, which is only 5 times more than your estimate， you have 4 months. Even if it is 2% efficient, you get ALMOST a month. Re: accelerating for many months at 1G is definitely bad physics, not only are you relativistic, you start getting into the kind of speeds where a minor meteorites will wipeout your ship. 1 gram meteorite with a relative velocity of 0.5c has 1.4e13 J of kinetic energy = 3.5 kton of TNT, so a small nuke.
    - garmaine 6y ago
      yeah the speed they travel through the inner solar system is pretty ludicrous, especially when you consider how much space junk is generated by all that activity.
  - TwoBit 6y ago
    I think comparing future technologies with today's Googke searches is unrealistic.
    - garmaine 6y ago
      Exploratory engineering does put firm limits on future capabilities. There are many possible steam engine designs, and I'm sure those we use today were unimagined in the 1820's. Yet none are more efficient than an ideal Carnot steam engine. The same principle applies here.
magicalhippo 6y ago
> the Epstein drive might as well be magic For me, good sci-fi does just that, ie limit the magic to one thing or technology, and use that to explore something interesting. Same with Altered Carbon. What would happen to society if we could swap bodies but keep our minds? That one piece of technology ("the stack") is magic, but from it follows lots of interesting exploration of the possible impacts on society etc. What I hate is when they try to explain the magic. Don't do that. It never works. Just assume it's there, someone discovered it, invented it whatever.
- TeMPOraL 6y ago
  But you have to try and explain the magic. If you didn't, your universe would break. Depending on the postulated mechanisms of action, the principles behind the magical invention will have vastly different impact on societies. For example, it matters how is it the ships can casually sustain a 1G burn for a week at a time. If it's efficient nuclear fusion, then the ships get bulky, energy is no longer a problem in the society at large, and the exhaust of said engine is a weapon of mass destruction. If it's subspace field shenanigans, then aforementioned impacts don't necessarily apply, but there is an open question of how small such subspace field combobulators can get, and what else could you do with them. Technologies have second-order consequences, and societies shape to accommodate them. Half the fun of science fiction is in exploring those. If you just call it magic and define it by a set of arbitrary rules, then your fictional universe will look shallow and inconsistent.
  - krapp 6y ago
    >But you have to try and explain the magic. If you didn't, your universe would break. Depending on the postulated mechanisms of action, the principles behind the magical invention will have vastly different impact on societies. Star Trek goes into intricate detail trying to explain its warp drives and comes off looking far less grounded than the vast majority of sci-fi properties with FTL or jumpgates or whatnot that either don't explain anything, or just offer a few details. Whether it breaks your universe depends on the themes you're trying to explore, such as the nth order effects of radical technologies on society. Most of the time, the story isn't about the technology (in the same way that Westerns aren't always about animal husbandry and gun manufacturing), and it's sufficient that you push some buttons, pull a lever and spaceship go brrr.

sxp 6y ago

The Expanse gives the illusion of real physics, but the actual physics are pretty fake. None of the orbits of the planets or the space ships follow realistic path. One of the authors mentioned that they didn't calculate the positions of the planets or the trajectories between them. So the Expanse isn't as realistic as 2001 or the Martian where the orbital mechanics play a key role in the story. This may seem like nitpicking, but if you want to discuss the politics of space, the distance between planets and the travel time between space polities becomes a critical aspect of politics. The Expanse is in an uncanny valley of hard sci-fi. It's not as realistic as Kerbal Space Program but use technology as a magical way to explore speculative scenarios like Star Trek did. And a core part of the first arc is a stealth ship which is not hard sci-fi at the Expanse's tech level: http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth http://www.projectrho.com/public_html/rocket/spacewardetect....

herodoturtle 6y ago
Well said. I recently got into a "the Expanse is not hard sci-fi" discussion, and the politics of space (between distant planets) was an interesting angle we hadn't considered.
feral 6y ago
Why can there not be stealth in space? The link you gave doesn't seem to have any arguments. Not saying you're wrong, just curious. Some simple arguments that it's not a ridiculous question: There is stealth on earth - paint and geometry that reduces EM signature. Why couldn't there be something similar in space? It's not like it's super easy to detect everything in space today either - we have big telescopes but regularly miss small asteroids?
- gambiting 6y ago
  Because your spaceship has to generate heat for various systems - at the very least, to keep its occupants alive. That heat, unlike on Earth, really stands out against the cold of space. You can hide the emissions of many vehicles on Earth, because Earth and its atmosphere is pretty warm compared to space in the first place. But in space all you need to do is look for heat signatures(infrared and others) and you will spot any vessel immediately. Some Sci-Fi has tried addressing it with plausible ideas - like for instance dumping all heat into shielded internal tanks, which have to eventually be vented(so that stealth cannot be infinite because you run out of heat storage capacity on board).

7373737373 6y ago

That's what I like about For All Mankind too, though it seems we have to wait for the second season for any real action to occur.

saberdancer 6y ago
I found For All Mankind really refreshing and enjoyable. One of my favorites is the fact they didn't shy away from prejudices of the time and they didn't make a series where guys from 60s have fully modern views.

simonh 6y ago

I don't really mind the Epstein Drive and really appreciate the effort to portray a decent stab at realism. It's very refreshing. The one thing that bugs me a bit is the way they conceptually represent the solar system in the show. If you follow the way the situation is represented you essentially have Earth on one side of the solar system, Mars in the middle and the asteroid field on the other side. That seems to be how the strategic situation is presented. To get from the asteroid field you essentially have to go past Mars, which is closer to the asteroids. If you think about the actual layout of the solar system this makes no sense, in reality Earth is about in the middle and any given asteroid is closer to the Earth at any given time than it is to half the rest of the belt. Again, it's fine. There's no way to capture the real dynamics of the solar system in the story without hopelessly bogging everything down, and for the purposes of the show the simplified model works fine. I suppose you could argue that during the period of the show by chance most of the main asteroids and Mars happen to be lined up on roughly the same side of the solar system as Jupiter, and then it basically works. It's just a bit of a fudge.

jusssi 6y ago
The strategy representation could also be rationalized as the Mars actively positioning their forces near most efficient transfer routes between points of interest. There seems to be relatively few places in the Belt and outside where anyone would want to go to, and guarding empty space where you'd expect no one to pass wouldn't make much sense. So ships transiting from Earth to the Belt would be going through Mars' solar orbit doughnut-of-influence. This of course ignores that with the Epstein drive magic, one could always trade travel time for going around ie. off-plane. There's plenty of, well, space for that. (Edit: according to the no-stealth-in-space link in a sibling post, one would be seen doing that, and likely get chased for it as being suspicious).
rob74 6y ago
Ah, the Epstein Drive, invented by Solomon Epstein, the Zefram Cochrane of The Expanse - seems like an unfortunate naming in retrospect, but I guess the novels were published a few years before Jeffrey Epstein became notorious...

hef19898 6y ago

The Expanse did a great job showing space battles on screen with a rather approriate distance. Star Wars and others, and I am a full blown Star Wars freak, did a good job with space battles. After the Expaense, it became little bit ridiculous, so. I resembles the problem films like Top Gun have with modern aerial combat. Already in that case, distances are so great that on-screen, the viewer is seeing nothing. For space battle, the enemy would maybe show as a small blip, if at all on screen. Especially with all the hyper advanced tech from Star Wars and Star Trek. This is also the reason why I igonre any stab at estimating weapon ranges based on on-screen scenes.

MaxBarraclough 6y ago

> even with that technology they'd never fight like that This applies to just about all fictional combat, no matter the setting.

lmilcin 6y ago

The Expanse is pretty bad at engagements or physics. They only look superficially well and that because other movies are completely unrealistic and space battles are there just to fill the screen with action and graphics effects, hopefully as background for the real narrative. Also, if you are looking for any kind of realism in Star Trek battles you are completely missing what the series is about. I like SF and I love Star Trek just as I love reading hard science fiction. Just don't mistake the two, because looking for realism in Star Trek would be like trying to do linguistic analysis on magical incantations in fantasy.

setr 6y ago

If you want a space opera with more realistic setups/politics/internal logic, Legend of the Galactic Heroes is top tier stuff