3 ms·

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 pa

by 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).
  - feral 6y ago
    Right - or maybe directionally radiating it away in a direction your adversary can't observe? The James Webb space telescope cools it's observing side instruments to 10s of degrees above absolute zero, using active cooling. I wonder how hard it would be to detect from it's cool side, at a space combat distance? Asteroids in the near solar system are normally 100-150 kelvin, apparently, and don't seem trivial to spot. All that still seems to allow room for stealth in a hard sci-fi setting.
    - gruez 6y ago
      There's other problems. Even if you contain your heat or vent it from a different side, you still need to produce hot exhaust to accelerate. If you don't, your position can be inferred from your last known position/acceleration. This and other points are discussed here: https://tvtropes.org/pmwiki/pmwiki.php/Analysis/StealthInSpace https://tvtropes.org/pmwiki/pmwiki.php/Analysis/StealthInSpa...
      - DennisP 6y ago
        In theory, you could fix the hot exhaust problem with a mass driver.
      - lumost 6y ago
        In the realm of hard sci-fi the detectability of an exhaust plume depends on a variety of factors including the ionization, temperature, shape, velocity, and angle of the plume wrt adversary, and the local medium. There are a number of methods one could theoretically use to minimize these factors. As an example, imagine the detectability of a small angle coherent neutron beam or the IR exhaust of a black hole starship. https://en.wikipedia.org/wiki/Black_hole_starship https://en.wikipedia.org/wiki/Black_hole_starship
  - brandmeyer 6y ago
    My personal fantasy tech for subspace is that it functions as an absolute zero heat sink. So heat engines can use absolute zero as the ultimate heat sink to build a Carnot contradiction: They don't actually sink any heat at all, and can extract all of the heat energy as work. Quantum mechanics forces them to actually sink a tiny amount of heat proportional to process entropy. Those tiny fluctuations are the "subspace signatures" that get detected anyway. Its still more fantasy than science, but hey, so are warp drive, hyperspace, and all that jazz :)
- moritonal 6y ago
  There is a relatively famous and long blog about this: http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth http://www.projectrho.com/public_html/rocket/spacewardetect....
- Cthulhu_ 6y ago
  IIRC in the series they turn off everything to stop emitting anything that can be detected - mostly IR radiation, I would guess. The rest of stealth in space is relying on the vastness of it. A spaceship a few kilometers away is already hard to see.
  - leetcrew 6y ago
    IIRC, they don't turn everything off. they turn off the reactor and run the ship's systems off of battery power. against a nearly 0 K thermal backdrop, there's no way an object like this could completely evade detection. they do actually address this in the show. you can infer from the dialogue that they don't expect to be "invisible"; rather, they are trying to be indistinguishable from space junk. I do think people are being a bit harsh in this thread. the show isn't perfect, but it's about as hard sci-fi as you can be while still getting renewed each season.
jiofih 6y ago
> None of the orbits of the planets or the space ships follow realistic path. I noticed that, but it is obviously a necessity for the TV version so that the plotlines are not interrupted. I’ll allow it
phire 6y ago
The physics are fine. Once you have 1G Torchships, orbital mechanics becomes very irrelevant. You basically take straight line paths between to points in space, constantly accelerating for half the journey then flipping over at the half way point to decelerate for the rest. Earth to Mars at closest takes 46 hours at 1G. Earth to Jupiter at closest takes less than 6 days. With 1G torch ships, the entire solar systems becomes accessible in less than two weeks journey. And the Expanse has ships that have much more acceleration.
- 4ggr0 6y ago
  I can't describe the feelings I feel in the last couple of weeks. It really feels like we are living in a (dystopian) future. Elon Musk is working on a brain-chip, people are wearing robot-arms and legs, space-travel gets faster and easier year by year etc. Just crazy, I am stoked to see what new technologies and possibilities will arise in the next few decades.
  - nine_k 6y ago
    I watch with grim satisfaction how well the cyberpunk books predicted our present and near future from 30+ years ago. (Satisfaction, because what's coming looks familiar, we've been warned.)
    - 4ggr0 6y ago
      I only started reading and watching Cyberpunk related things about a month ago, so it's interesting to see how far we already are.
  - Cthulhu_ 6y ago
    The thing with the prosthetics is that I feel like there's hundreds, if not thousands of companies and individuals working on them, but there doesn't seem to be any convergence, or more importantly, mass production - meaning that prosthetics remain expensive and made-to-measure. This is a thing with a lot of things that look very high-tech or science fiction. That said, video calling was the realm of exclusive, high-tech / demos for a long time, then without really being aware of, it's been available in everyone's pocket for a long time now. It went from near-sci-fi to mainstream in the blink of an eye.

by sxp 6y ago

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).
- feral 6y ago
  Right - or maybe directionally radiating it away in a direction your adversary can't observe? The James Webb space telescope cools it's observing side instruments to 10s of degrees above absolute zero, using active cooling. I wonder how hard it would be to detect from it's cool side, at a space combat distance? Asteroids in the near solar system are normally 100-150 kelvin, apparently, and don't seem trivial to spot. All that still seems to allow room for stealth in a hard sci-fi setting.
  - gruez 6y ago
    There's other problems. Even if you contain your heat or vent it from a different side, you still need to produce hot exhaust to accelerate. If you don't, your position can be inferred from your last known position/acceleration. This and other points are discussed here: https://tvtropes.org/pmwiki/pmwiki.php/Analysis/StealthInSpace https://tvtropes.org/pmwiki/pmwiki.php/Analysis/StealthInSpa...
    - DennisP 6y ago
      In theory, you could fix the hot exhaust problem with a mass driver.
    - lumost 6y ago
      In the realm of hard sci-fi the detectability of an exhaust plume depends on a variety of factors including the ionization, temperature, shape, velocity, and angle of the plume wrt adversary, and the local medium. There are a number of methods one could theoretically use to minimize these factors. As an example, imagine the detectability of a small angle coherent neutron beam or the IR exhaust of a black hole starship. https://en.wikipedia.org/wiki/Black_hole_starship https://en.wikipedia.org/wiki/Black_hole_starship
- brandmeyer 6y ago
  My personal fantasy tech for subspace is that it functions as an absolute zero heat sink. So heat engines can use absolute zero as the ultimate heat sink to build a Carnot contradiction: They don't actually sink any heat at all, and can extract all of the heat energy as work. Quantum mechanics forces them to actually sink a tiny amount of heat proportional to process entropy. Those tiny fluctuations are the "subspace signatures" that get detected anyway. Its still more fantasy than science, but hey, so are warp drive, hyperspace, and all that jazz :)
moritonal 6y ago
There is a relatively famous and long blog about this: http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth http://www.projectrho.com/public_html/rocket/spacewardetect....
Cthulhu_ 6y ago
IIRC in the series they turn off everything to stop emitting anything that can be detected - mostly IR radiation, I would guess. The rest of stealth in space is relying on the vastness of it. A spaceship a few kilometers away is already hard to see.
- leetcrew 6y ago
  IIRC, they don't turn everything off. they turn off the reactor and run the ship's systems off of battery power. against a nearly 0 K thermal backdrop, there's no way an object like this could completely evade detection. they do actually address this in the show. you can infer from the dialogue that they don't expect to be "invisible"; rather, they are trying to be indistinguishable from space junk. I do think people are being a bit harsh in this thread. the show isn't perfect, but it's about as hard sci-fi as you can be while still getting renewed each season.

jiofih 6y ago

> None of the orbits of the planets or the space ships follow realistic path. I noticed that, but it is obviously a necessity for the TV version so that the plotlines are not interrupted. I’ll allow it

phire 6y ago

The physics are fine. Once you have 1G Torchships, orbital mechanics becomes very irrelevant. You basically take straight line paths between to points in space, constantly accelerating for half the journey then flipping over at the half way point to decelerate for the rest. Earth to Mars at closest takes 46 hours at 1G. Earth to Jupiter at closest takes less than 6 days. With 1G torch ships, the entire solar systems becomes accessible in less than two weeks journey. And the Expanse has ships that have much more acceleration.

4ggr0 6y ago
I can't describe the feelings I feel in the last couple of weeks. It really feels like we are living in a (dystopian) future. Elon Musk is working on a brain-chip, people are wearing robot-arms and legs, space-travel gets faster and easier year by year etc. Just crazy, I am stoked to see what new technologies and possibilities will arise in the next few decades.
- nine_k 6y ago
  I watch with grim satisfaction how well the cyberpunk books predicted our present and near future from 30+ years ago. (Satisfaction, because what's coming looks familiar, we've been warned.)
  - 4ggr0 6y ago
    I only started reading and watching Cyberpunk related things about a month ago, so it's interesting to see how far we already are.
- Cthulhu_ 6y ago
  The thing with the prosthetics is that I feel like there's hundreds, if not thousands of companies and individuals working on them, but there doesn't seem to be any convergence, or more importantly, mass production - meaning that prosthetics remain expensive and made-to-measure. This is a thing with a lot of things that look very high-tech or science fiction. That said, video calling was the realm of exclusive, high-tech / demos for a long time, then without really being aware of, it's been available in everyone's pocket for a long time now. It went from near-sci-fi to mainstream in the blink of an eye.