Thursday Throughput: Units of Measure Edition

Michael Siegel

Michael Siegel is an astronomer living in Pennsylvania. He is on Twitter, blogs at his own site, and has written a novel.

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  1. Chip Daniels
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    I very badly want there to be extraterrestrial life, and very badly want human space exploration to happen.
    But I’ve grown more and more resigned to the idea that space travel for humans just is like Fetch, just not going to happen.
    I’m partial to the arguments that the environment of space is so incredibly hostile, and the commercial value of other planets is so paltry that it will never be commercially viable to have for example, mining colonies on Mars or whatnot because the costs and energy required just to sustain life there would always outweigh whatever value is mined.

    In addition, the advances of AI and robotics seem like it would be far more efficient to have robotic probes and machines operating which don’t have the complex needs that humans do.

    As for alien life, I think it is much the same- Its hard to imagine a form of life that is conducive to space, and as Michael points out, the species that has enough recourses to travel between stars probably doesn’t need to do so.Report

    • Oscar Gordon in reply to Chip Daniels
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      It really comes down to, how do we get out of the gravity well? As long as the cost/kg of climbing out of the gravity well is high, you are right.

      If that cost becomes reasonable, however…Report

      • Slade the Leveller in reply to Oscar Gordon
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        Isn’t the bigger problem exposure to cosmic radiation?Report

        • Oscar Gordon in reply to Slade the Leveller
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          If I can lift mass at a reasonable cost, then no.

          There is very little radiation out there that I can not shield against, given sufficient mass budget. I was actually just reading about a very interesting fungus here on earth that just loves itself some cosmic radiation, and a 20cm layer of it could effectively shield a station from all the radiation it would normally suffer. Water is another handy radiation shield.

          But man, lifting that much mass right now, that would be pricey.

          Honestly, the lack of gravity on our bodies is really the largest hurdle. Our bones start to lose mass almost immediately once gravity is not acting on them.Report

          • Slade the Leveller in reply to Oscar Gordon
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            Wow, that fungus thing is interesting. I know in Kim Stanley Robinson’s Mars trilogy the colony ship used water, but, like you say, water is really heavy.Report

          • Michael Siegel in reply to Oscar Gordon
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            Holy smokes, I’m stealing that fungus idea for a story. What a great discovery!Report

          • Jaybird in reply to Oscar Gordon
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            20 cm? Golly jeepers. That’s… (holds both hands out in front of him, touching)

            That’s a lot of cms.Report

            • Oscar Gordon in reply to Jaybird
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              In space, not so much.Report

              • Jaybird in reply to Oscar Gordon
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                I was thinking about between the (space thing) and the vacuum.

                Say what you will about the space shuttle shielding, but it was 1-5 inches.Report

              • Oscar Gordon in reply to Jaybird
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                Right, and that was a lot, because you had to account for those dimensions and mass on a thing that had to lifted, and glide back to earth.

                If I’ve got a permanent space station and the ability to lift mass at a reasonable price, my perspective on what counts as ‘thick’ shifts considerably towards (or beyond) “20cms ain’t nothing!”

                ETA: I mean, if you can provide shielding using a thinner space between hull plates, great! But filling the empty space between hull plates is largely free when the thing doesn’t have to fly through atmosphere.Report

              • Jaybird in reply to Oscar Gordon
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                Wait, can take it out there and seed it and it can grow out there?Report

              • Oscar Gordon in reply to Jaybird
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                Possibly, depends on how fast it grows and what kind of growing medium (food, structure) it needs. If it’ll take 20 years to fill the walls, we’ll need to haul it up. If it take 2 years, we’ll probably still be building out the interior by the then.Report

              • Jaybird in reply to Oscar Gordon
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                Okay. That turns it from “that’s a lot” to “maybe it’s not?”

                I suppose I’d need to know how dense the fungus would be. If a liter of food results in 12 liters of fungus… that’s a pretty good tradeoff.Report

              • Oscar Gordon in reply to Jaybird
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                Also depends on the definition of “food”. If the fungus is happy to use cosmic radiation to turn human waste into radiation shielding, well, then you are already lifting all the fungus food, just needs about 12 hours of biological processing before feeding it to the fungus.

                And if it doesn’t… we are getting awful good at tweaking the genomes of single cell life.Report

              • Jaybird in reply to Oscar Gordon
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                Yeah, some gain-of-function research on some fungus that eats radiation and poop.

                What could possibly go wrong?Report

              • Oscar Gordon in reply to Jaybird
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                Pessimists…Report

          • Michael Cain in reply to Oscar Gordon
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            Honestly, the lack of gravity on our bodies is really the largest hurdle. Our bones start to lose mass almost immediately once gravity is not acting on them.

            And as the time in micro gravity increases, assorted problems with fluid distribution show up, affecting vision, cardiovascular health, and neurology. I’ve seen at least one report from someone who summarized the last as “it’s beginning to look like sustained micro gravity makes humans stupider.”

            If I can lift mass at a reasonable cost, then no.

            Whatever else we might want to say about Elon Musk, he’s doing rocketry design to reduce the cost to LEO or lunar orbit. On the other hand we have the United Launch Alliance whose large effort is to build a single-launch, minimal mass to the moon and return, $2B per launch boondoggle. If I had the authority, I’d be looking for whoever approved letting ULA reproduce Apollo with better materials and fire all their butts.Report

            • Oscar Gordon in reply to Michael Cain
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              Yep, we evolved in a gravity well, thus we must exist in one, or something that mimics one.

              Musk is a hot mess, but SpaceX is doing good work.Report

              • Michael Cain in reply to Oscar Gordon
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                Yep, we evolved in a gravity well, thus we must exist in one, or something that mimics one.

                If I were pinning my hopes for the human race on space colonization of some sort, my first two questions — which are, I think, completely unanswered currently — would be: (1) how many humans does it take to support a society at our current level of tech or somewhat higher; and (2) what’s the minimum continuous acceleration necessary to grow a human from zygote to adult?

                My entirely unscientific guess for the first is between three and thirty million, depending on how good the automation is. Most people seem to think a lot smaller than that. I think that’s because they think about a small number of people at the top, but not how big the pyramid is that supports those people.

                If the answer to the second one is 5.0 m/sec², then most of the plans are screwed. No matter where you go, you have to build centrifuges capable of supporting a sizeable fraction of the population (and see the previous paragraph) on a continuous basis.

                And to borrow an idea from one of Chip’s comments, the worst case scenarios for climate change (or ecosystem collapse from other causes) mean colonists have a very limited time frame to get to where they’re not dependent on Earth being a functional high-tech world.

                Yeah, I’m a pessimist these days.Report

            • JS in reply to Michael Cain
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              ” On the other hand we have the United Launch Alliance whose large effort is to build a single-launch, minimal mass to the moon and return, $2B per launch boondoggle.”

              Again, in defense of NASA, Congress keeps shutting down their plans every 4 years and giving them new ones.

              It’s amazing they can do ANYTHING as, by my count, the shuttle replacement has been authorized, fully cancelled, and everyone laid off at least three times. Possibly four.

              All work lost, employees gone to other jobs, etc.

              And not because NASA hated the idea of a shuttle replacement, but because Congress uses it as a political football.

              If Ford was tasked with designing a car, then that was cancelled and told an airplane, then that was cancelled in back to a car but a truck this time, then that was cancelled and then it was an EV 18-wheeler (with at least a year to three years between new ideas), and someone asked “Why has it cost billions and ten years and you don’t have your EV 18 wheeler” I’m pretty sure Ford would snap.

              NASA would absolutely like to make a cheap cargo rocket. They keep trying. And then all their money is taken away, their engineers fired, their work scrapped — and then two years later they’re given a new task, a new rocket, just different enough that 99% of their previous work is wasted — not that anyone who worked on it is STILL THERE.Report

    • Michael Siegel in reply to Chip Daniels
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      This is exactly something I am wrestling with in my new novel. And I think I had a breakthrough last night. Hopefully will be able to share it with you in the next five years or so.Report

  2. Oscar Gordon
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    ThTh7: Why peer review is so important.Report

  3. Mark Draughn
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    The alien threat scenario that seems most plausible to me is that it may be possible to build interstellar kinetic impactors — ships powered by fusion or antimatter or whatever that can accelerate to a significant fraction of the speed of light, coast across the space between the stars, and slam into planets hard enough to kill them.

    Even now, we have vague ideas about how such weapons might be built. And if we can do it, aliens can do it. And the aliens will know we can do it to them. Unless they do it to us first. It wouldn’t be a war of conquest but of total annihilation. And it only takes one really paranoid civilization.

    And high-velocity interstellar spacecraft, which are probably kind of difficult to build. Still, I wonder if the first sign of extraterrestrial life will be a bright flash on the horizon and a fireball erupting into the sky…Report

    • Reformed Republican in reply to Mark Draughn
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      If the only interaction possible between planets is to attack one another, because travel would be impossible, it seems like there would be no reason to bother attacking, I guess that is where the paranoia comes in though. The other civ might be crazy enough to do it, just because they think you are crazy enough.

      The Remembrance of Earth’s past series (which I think I was introduced to by a post here) deals with this very issue.Report

      • Mark Draughn in reply to Reformed Republican
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        Yeah, it’s the logic of the Cold War. If either the United States or the Soviet Union had become confident that they could launch a first strike that would destroy all of the other side’s missiles in their silos, I’m not so sure one of them wouldn’t have done it.Report

    • veronica d in reply to Mark Draughn
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      Targeting would be pretty difficult. After all, we have to do various course corrections for our interplanetary probes, but the margin of error there is way less than for something interstellar. Moreover, at near-luminal velocities, it would take a lot of energy to retarget as the payload got near to its destination.Report

  4. CJColucci
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    Will our nearest intelligent neighbors have picked up original broadcasts of The Honeymooners by now and concluded that we could send women to the moon?Report

  5. Dark Matter
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    Aliens could reasonably want our planet for the same reason we’d want other planets. The Earth is in the goldilocks zone (not too warm or too cold), it has decent minerals for a civilization, etc. If the Earth didn’t already have life it wouldn’t be hard to terraform it into working for us.

    One of the best ways for us to expand is to send robot ships to other planets, terraform them, and then grow people there so they can create a civilization. This defeats the distance problem and the time problem.

    As things stand now we’re on course to take over the Galaxy in a few million years. If someone else has already started that, we might have a robot ship show up here and then we’ll see what it’s owners think of ethics.Report

    • North in reply to Dark Matter
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      I suppose so, but wouldn’t an alien civilization capable of “reaching out and touching us” already have the tech to build habitats in space (with the near limitless resources of space already out there to use to do so). So of what use would our alien world with its gummy mess of complex microbial life really offer to them?Report

      • Oscar Gordon in reply to North
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        Depends on how much population pressure there is an how many liquid water planets there are at about 1G? Given enough pressure, and enough scarcity, scrubbing a prime bit of real estate clean of the locals might be a reasonable thing.

        I mean, we did it.

        ETA: The thing to keep in mind is aliens are, well, alien. We have no hard evidence that life must evolve on liquid water planets that have a gravity of 1G. Maybe we get too much sun, or have way too much atmospheric pressure, or too little, etc. We can’t assume we have prime real estate for other species.Report

        • Dark Matter in reply to Oscar Gordon
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          Increase the gravity much past where we are and they don’t get off the planet or chemical reactions seriously change. Decrease the gravity much and the air leaves the planet.

          Now throw in different chemistries or ice planets and it might get very weird… but we’re not sure if different chemistries are possible and it’s also not clear an ice planet can reasonably get technology (it’s implied there’s no opposable thumb and no fire).

          The big problem with this reasoning is we lack information and we might be the weird ones for liking this temp gravity, etc. There might be an easier way to get life so we’re the likely odd ones out.

          We won’t know until we do a ton of exploring and find out what experiments mother nature has run.Report

        • North in reply to Oscar Gordon
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          I guess? But sterilizing the Earth enough to get rid of the entire microscopic biosphere strikes me as very cost prohibitive and I am imagining that aliens would probably not want to be swimming in Terran microscopic lifeforms for heath reasons.Report

          • Oscar Gordon in reply to North
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            Maybe, or maybe they just want to get rid of the local life intelligent enough to object vigorously to their taking over.

            Too many assumptions, not enough data.Report

      • Dark Matter in reply to North
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        My non-scientific WAG is we’ll get the tech to build robots which can visit other planets long before we’ll get habitats in space. Space is seriously not friendly.

        That’s over and above the ton of reasons we have to flee this system.
        1) Aliens may come in and kill us.
        2) The sun may/will blow up (turning into a Red Sun counts).
        3) We may kill ourselves.
        4) Something else may kill us (large rock, whatever).

        There are serious people right now who think we need to branch off of the planet just to take our own extinction off the table.Report

        • Chip Daniels in reply to Dark Matter
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          I agree with all your points, but can’t help but see the bleak absurdity in the last sentence.

          We can’t cooperate sufficiently to sustain human life on the one planet that is so insanely suited to human life that it takes a tremendous amount of effort to overcome its natural fecundity and vibrant life.

          So therefore, as an insurance policy you know, we will venture out to environments which would demand a thousand times more close cooperation and skill just to sustain the bleakest form of human habitation.

          Yeah, that’s a plan.Report

          • Dark Matter in reply to Chip Daniels
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            Cooperation won’t be the issue for the Earth if some rock lands on us.

            So therefore, as an insurance policy you know, we will venture out to environments which would demand a thousand times more close cooperation and skill just to sustain the bleakest form of human habitation.

            In theory we have robots do the heavy lifting before anyone is even alive.

            That’s over and above getting a fresh new start will get rid of a ton of stuff that only exists because it exists.Report

          • Oscar Gordon in reply to Chip Daniels
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            Again, it all comes down to getting out of the gravity well. If we can make that cost reasonable, then ‘bleak’ starts to be less so.

            Right now, living in space is like living aboard an old wooden frigate back when those were the pinnacle of Naval Technology. Trust me, it wasn’t pleasant by any stretch of the imagination. If you told a sailor back then that in a couple of hundred years, people would be cruising the ocean on floating resorts for relatively reasonable fares, they’d have a hard time believing you.

            Once that cost starts coming down, the necessities that make things bleak can be easily engineered away.Report

            • North in reply to Oscar Gordon
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              That lack of gravity though. Dissolving into a floating bag of meat due to lack of gravity would be awful even in luxurious settings. Can we spin a ship/habitat enough to simulate earth gravity or does that come with its own problems?Report

            • veronica d in reply to Oscar Gordon
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              I feel as if it’s more complicated than that. Certainly engineering problems can be solved, and humans are quite clever, but we are pushing against pretty hard limits of physics perhaps in a way different from ship building.

              An analogy: over time engineers got past the sound barrier. Nowadays supersonic flight is easily achievable. By contrast, the light speed barrier — well it’s a different beast. Even getting close to light speed involves exponentially growing energy requirements, which requires fuel, which requires mass, and even antimatter (if that’s even a plausible technology) hits the E=MC^2 barrier.

              I don’t want to dismiss our ingenuity. For example, the uncertainty principle puts hard limits on the resolution of telescopes. In turn, we developed interferometers. That’s pretty neat.

              The point is, I don’t want to be the modern equivalent of the person who said, “We’ll never break the sound barrier” — however, these are different kinds of problems than those were. Some things will require new physics, and no one can predict what will happen.Report

              • North in reply to veronica d
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                The speed of light never stops depressing me. The universe is so vast and it is so slow and yet seems immutable. Depression.Report

              • Dark Matter in reply to North
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                The speed of light never stops depressing me.

                I go back and forth of this.

                Without the speed of light, everything in our Galaxy is next door, which means anything that is older than us is next door. We get to Lovecraft real easy this way.Report

              • North in reply to Dark Matter
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                I get it. The vastness insulates us from the horrors but it insulates us from the wonders as well. The vastness is a horror of a sort, an unyielding implacable empty horror.

                And if the speed of light is insurmountable, as it certainly appears to be, then so much is utterly beyond our reach.Report

              • Oscar Gordon in reply to veronica d
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                I’m thinking much more pedestrian, like a toilet that doesn’t make you feel like you are getting a vacuum enema.

                That new physics kinda stuff is a bit further out than just tossing some habitats between here and the moon / Lagrange points.

                Now, if we can manage to crack that fusion nut….Report

              • Dark Matter in reply to veronica d
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                these are different kinds of problems than those were. Some things will require new physics, and no one can predict what will happen.

                Exactly this.

                We can build robots, have them go to other planets and build humans with our current Physics and reasonably expected increases in technology.Report

            • Chip Daniels in reply to Oscar Gordon
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              I was commenting more on the idea that Spaceship Earth, the most perfectly designed spaceship for human habitation ever conceived, will become unsuitable for human life due entirely to our own stupidity so therefore Spaceship X will somehow produce a different outcome.

              I’m imagining that on Spaceship X there will be some percentage of people who piss into the drinking water because, well, its easier than walking down the hall and you’re not the bossa me.

              And other groups of people will tear down the hydroponic towers because damned if those assholes in Pod Bay Ceta are gonna get their hands on it, another group will try to shut down the oxygen generators because the Colander prophesy of the FSM said they were unnatural and yet another group will infect themselves with a virus and go around licking doorknobs because Freedom.Report

              • Oscar Gordon in reply to Chip Daniels
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                Ha! Yeah, OK, that’s a fair concern.Report

              • Dark Matter in reply to Chip Daniels
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                This type of world would be amazingly technological and the profoundly ignorant wouldn’t have a spot.Report

              • Chip Daniels in reply to Dark Matter
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                You already live in a world of space stations and robot surgeons and genetic engineering, and human behavior hasn’t changed one iota since Juno confronted Jupiter over his dalliance with those nubile nymphs.Report

              • Dark Matter in reply to Chip Daniels
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                Everyone is hardly a robot surgeon, and the really stupid stuff underperforms in that kind of person and overperforms in the opposite.

                Also part of the whole “robots raise children” is I don’t see how they get brainwashed into believing in [whatever] God. Now maybe some other type of magic thinking rises to take it’s place.Report

        • North in reply to Dark Matter
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          Your #2 is objectively true. At some point the Sun will destroy the earth. Our entire Terran biosphere is depending on humanity to save it Human kind are the secular “chosen ones”.Report

          • Oscar Gordon in reply to North
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            IIRC, yes, spinning enough of the ship/habitat to simulate gravity prevents bone & muscle loss, provided you spend enough time there &/or do a prescribed workout regimen while there.

            At least, we think so. We haven’t built such a habitat yet to prove that out.

            ETA: Misthreaded, sorry North.Report

            • North in reply to Oscar Gordon
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              No big. So if we built a huge ring world in orbit of the sub we could spin it to simulate earth gravity?Report

            • Dark Matter in reply to Oscar Gordon
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              1) In theory, lots of local spin deals with gravity.
              2a) Radiation requires either more mass than we can make economic
              2b) or re-engineering humanity so we’re not vulnerable to cancer/radiation.
              3) The level of infrastructure to keep things warm/wet/aired over a large area for lots of people over a long period of time is non-trivially large.
              4) Worrying about getting hit by very small very fast objects is a thing.

              “Spin” suggests one scale of things while some of these others suggest a much larger scale.Report

              • Oscar Gordon in reply to Dark Matter
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                1) Yes, just need to build something to prove that out.
                2) See my comments about radiation hungry fungus and needing to drop the cost of lifting mass*.
                3) Not really. Again, make the cost to lift mass reasonable, and you can deal with those issues. And to be honest, air & humidity are a concern (making things air and water tight is always an issue, even our best will probably still leak a noticeable amount of air and water over time), but warmth, not so much. Heat transfer in space is only by radiation, which is slow. Probably have more trouble getting rid of waste heat than you would keeping things warm.
                4) Yes, and to date, we don’t have armor that can handle that without hitting bulkhead thicknesses that really make the eyes go up. Best choice is to be in places where there aren’t a lot of small things moving fast. Absent that, it comes back to naval engineering – redundancies and sealable bulkheads. You get hit by a MM, that section either deploys an auto-seal, or it gets closed up until repair crews can respond.

                *One thing to keep in mind is that the cost to lift has something of a break over point (no, I don’t know where that is), where we can lift enough mass to establish industrial infrastructure, and then go fetch rocks for raw materials. We aren’t there yet, not even close, AFAIK, but there is a point where lifting raw materials out of the gravity well, even when it’s cheap, begins to be more hassle than it’s worth, once you can process the raw materials in space itself.Report

  6. Brandon Berg
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    ThTh5: I’ve been confused on this point, since I figured that infection or a whole virus vaccine would give you antibodies to many parts of the virus, making your immune system robust against variants. This clears up a lot of that. Thanks!Report

  7. North
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    [ThTh10] And as usual environmentalists blast themselves in the groin with their vendetta against nuclear power. Quelle surprise.Report

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