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    Toughsf

    toughsf.blogspot.com · Publication · on HN since 2016

    Authors of a site that works out the physics of spacecraft, space weapons and megastructures, aimed at science fiction worldbuilding.

    Visit blogRSSHN submissions
    SpacePhysicsScience
    What HN says

    HN commenters cite its laser weapons posts as strong arguments, and use it to check whether sci-fi tech such as fusion drives holds up.

    Stats for nerds
    37HN people shared it
    32linked in comments
    525story points
    Mar 2026last shared
    2017people per year2026

    Top posts on HN

    1. 1
      Space Tethers: Stringing Up the Solar System
      3 people · 147 points · first shared 2020 · 55 comments on HN
    2. 2
      Anti-Orbit Laser Submarines (2017)
      2 people · 82 points · first shared 2021 · 31 comments on HN
    3. 3
      Nuclear Reactor Lasers: From fission to photon (2019)
      1 person · 67 points · first shared 2025 · 10 comments on HN
    4. 4
      Realistic fusion drive with Epstein Drive-like performance
      10 people · 64 points · first shared 2019 · 37 comments on HN
    5. 5
      Laser Launch into Orbit
      1 person · 60 points · first shared 2025 · 35 comments on HN
    6. 6
      Thermal Decomposition of CO2 with Nuclear Heat
      1 person · 44 points · first shared 2019 · 62 comments on HN
    7. 7
      Nuclear Explosively Formed Penetrators
      2 people · 16 points · first shared 2019 · Discussion on HN
    8. 8
      The Lofstrom Loop: A Bridge to Space
      2 people · 6 points · first shared 2024 · Discussion on HN
    9. 9
      Fusion Highways in Space (2021)
      2 people · 5 points · first shared 2021 · Discussion on HN
    10. 10
      The Laser Revolution Part I: Megawatt beams to the skies
      3 people · 3 points · first shared 2025 · Discussion on HN

    What HN people wrote when they linked it

    • lazideJun 2024

      Rather the opposite isn’t it? What you’re saying is ‘regardless of relative benefit or cost, humanity would make the decision to do interstellar travel - because reasons’.

      I’m pointing out that relative benefit and cost matter and tend to drive decisions - and that the massive cost with (currently) no plausible benefit which could outweigh it, makes it unlikely we would end up taking that course.

      Unless we discover new physics, or new ‘value’ somewhere which would justify it.*

      Energetically, for instance, even if we found a planet of pure most expensive thing we can think of (except perhaps for antimatter, though that is a more complicated discussion) just a few light years away, it would never be economic to go get it based on our current understanding of physics.

      Even sending a physical probe would be of dubious value, especially considering everyone who would be alive or benefit from anything it could ever provide (including information) would be long dead before we could even find out if it could talk to us over those distances or had arrived.

      This is so obvious, btw, that sci-fi writers always have to come up with new physics (or outlandish extrapolations of current thoughts on potential physics - see the Expanse’s Epstein drive, or Star Trek warp tech and subspace communications) for the story to be even a little plausible or interesting. [http://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html?m=1]

      And it always has to be a mcguffin, because…

    • upwardboundAug 2022

      The reason I'm personally most excited is interplanetary or even (generation ship) interstellar travel. Fusion fuel is the only practical fuel we know of with enough energy density to provide enough "umph" for long-distance trajectories to be traveled along, at speeds faster than what the Voyager probes had to achieve using multi-year planetary slingshot trajectories.

      Fusion rocket information:

      https://en.wikipedia.org/wiki/Fusion_rocket

      https://www.iter.org/newsline/-/3303

      http://www.projectrho.com/public_html/rocket/realdesignsfusion.php

      A supplement to a fusion power plant: https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket

      http://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html

      The only fuels that could achieve better energy density than fusion fuel would be antimatter, or maybe some fanciful sci-fi thing we may discover down the line, such as quark fusion ( https://www.sciencealert.com/new-quark-fusion-releases-significant-energy-won-t-make-weapons ) or subatomic compression ( a concept from fiction that involves packing an immense amount of solid electrons together so tightly that the electrostatic repulsion functions as a compressed spring (perhaps using mutual gravitation almost but not quite strong enough to be a black hole as a way of preventing disastrous spontaneous decompression) ).

    • klyrsOct 2022

      > The idea that a magical new engine would suddenly appear that made many of the things in the tv series possible.

      Assuming you're talking about the Epstein Drive and not the protomolecule... it didn't suddenly appear, it was invented. And, surprisingly enough, it's way closer to realistic than most scifi.

      http://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html?m=1

      > The idea that there would be a complete backtrack in labor rights and labor safety (the ice asteroid mining scene).

      What labor laws cover the asteroid belt today? Or, closer to home, the moon? If an earthly nation claims some territory out there its own and seeks to enforce the law, that's one thing. But what if a private company sends workers out there in unclaimed space? Humanity hasn't had access to such a lawless frontier in centuries, but we've got a lot of ugly history to look back on. Civil rights are not won by optimists, they're won through bloody and protracted fights. Look no further than Apple to see that companies in today's economy are still fully on board with slavery and sweatshops, and Apple is one of the "good guys" known for holding vendors' feet to the fire over human rights abuses.

    • fennecfoxyApr 2023

      Ah, lovely to see Murderbot mentioned, I've just been re-reading it.

      I think it's fine to take scifi tech with a grain of salt; most authors skip the absolute technical details so we just have to assume that things work in some way we don't currently understand. Someone did the calculation for the Epstein and it doesn't look great: http://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html but only based on the vague technical details provided in the books.

      The Jean Le Flambeur trilogy is one of my favourites, it does a LOT of quantum hand-waving but the price is worth it for all of the amazing things in that universe. "This sounds so fucking cool" > "That wouldn't work irl" for good sci-fi imo. As long as they don't mess with thoroughly understood concepts and rely on "things we don't know yet".

    • DennisPNov 2025

      Regarding reproduction, I'm willing to write that off to advanced medical technology doing DNA repair. Most of the plot wouldn't be that different with slower space drives, so I wasn't too bothered by that either.

      But fwiw, it turns out it is possible to get that level of rocket performance, if ToughSF got their numbers right:

      https://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html

      It wouldn't look the same and the power level would be higher than what all of civilization uses today, but the amount of fusion fuel isn't all that remarkable. The design uses helium-3, which could be collected in large quantity from Uranus and Neptune.

    • fennecbuttMay 2025

      Perhaps for casual readers.

      But say you write a pop culture hit, people start looking deeper, and the gaps become glaring.

      Like the fusion drives in the expanse, it's hand waved on the first read through, but on the second I found that someone had calculated it online (like this https://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html?m=1) and now it kinda ruins the vibe, the author should have chosen something outside of current science (basically magic) or used a technology that's feasible.

      Also, the ships fucking explode when they lose magnetic fusion containment...whereas in reality it would just dissipate...

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