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Building a Dyson Sphere around a Class-B Star

  1. Aug 17, 2016 #1
    I was idly thinking of Dyson Spheres and solar energy when this idea came to me: say you were technologically advanced enough to build a perfect, Dyson sphere and were able to deal with the problems of drift--in other words you belong to a really, technologically advanced civilization! It occurs to me that you would probably build something like this around a Class-B or Class-A star because you could build another smaller, globular structure around the Class-B star that could shield the inhabitants from really dangerous emissions from the star--and the globular shield could use such higher energy emissions to produce energy and possibly even exotic matter. You would need the globular shield anyway to give the inhabitants the semblance of day and night, why not use it for production as well?

    Because of the level of assumed technological ability of builders what I'm about to ask may be a ridiculous question--but I'm going ask anyway: What would be the advantages and disadvantages of building such a structure around a Class-B or Class-A star?
  2. jcsd
  3. Aug 17, 2016 #2
    If they're that advanced why would they need such a clumsy energy source?
  4. Aug 17, 2016 #3
    A perfectly legitimate question. It may be the difference between making precious gems and being able to dig them out of the ground. Digging is always likely to be a bit cheaper. I admit this is a bit of idle speculation that caught my fancy. I should take this time to apologize to Ryan and Evo for not posting this in the writing section, but I don't have any story ideas attached to this. I'm just intrigued and I thought I would toss it out there. But you're right, a civilization advanced enough to do this might very well be advanced enough to not bother doing this.
  5. Aug 17, 2016 #4
    They make diamonds in the lab now. Just sayin'.

    But let's say that they didn't build this, it was a gift from a more advanced race. It fits their technological level so it's reasonable to have it. How's that?
  6. Aug 17, 2016 #5
    The thing to remember about a Dyson Sphere is no matter how power is used or made there is still a lot of desirable real estate to be had. That would probably be the main selling point to any race. Those advanced aliens may not be in such a hurry to give the real estate to someone else.
  7. Aug 17, 2016 #6
    Suppose they built a bunch of robotic engineers to do this kind of thing. Just set the robots loose as they evolved into something that didn't need an instrumentality. Would that fly?
  8. Aug 18, 2016 #7
    I wonder if we're talking past each other. I'm interested in how viable it would be to build a Dyson Sphere around something really big, hot, and volatile. While how it got built, and by who, are interesting questions to consider they aren't on my mind right now.
  9. Aug 18, 2016 #8


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    I read Ringworld years ago, I am not at all versed in whatever are thought to be the main design considerations of a Dyson sphere, so this may be very naive.

    My perspective is to consider the surface temperature desired and the diameter required to get that temperature vs the energy output of the star and how much material is available to create a sphere of that diameter and how to vent extra energy out the back of the sphere if needed to maintain temp if things get too warm and how long the star will produce the needed energy to maintain the desired temperature and then you know if the star you are considering is suitable.
  10. Aug 18, 2016 #9
    I was addressing this:

    "Those advanced aliens may not be in such a hurry to give the real estate to someone else."
  11. Aug 18, 2016 #10
    Oh I see what you mean. One thing to remember about those aliens is they would build a DS to their specs, not ours. They might like more or less gravity, They could have a different, not quite compatible, recipe for an atmosphere. Given the thing I'm most concerned about in this scenario, they might be able to take a little more hard radiation than we can. All these things would have to be considered before we move in.

    But what immediately intrigues me is whether or not those uber-aliens would find the idea of building a DS around a Class-B star, which coughs up a lot more radiation in the ultra-violet to X-ray spectrum than Sol does, attractive. They idea I have is that they could use the higher energy output to create more energy for themselves. the downside is that the unfiltered output of a Class-B star would put you in the Cancer Ward and cook the atmosphere into something un-breathable. So you have to put some sort of filter/shield between the star and the ground. I thought I had was that the shield/filter would be the logical place to turn that hard radiation into something useful.

    If I were any less naive than you are I wouldn't have submitted this thing. They whole point of asking this question is to see how naive I am. If you read the paperback version of Ringworld circa 1975 you should remember the artist's depiction of the ringworld: a large band surrounding a sun with a smaller band sitting between the sun and the ringworld. The smaller band had shaded patches, and was designed to mimic the shifts of day and night. The shield/filter I'm talking about would be that smaller band. However, in my scenario, that band would be another sphere--and it would have an additional task: filtering out and utilizing the higher frequency radiation that a class-B star to kick out. Those uber-aliens would not have evolved in a star system with a class-B star because nothing has time to evolve in a star system with a class-B star. The star will go nova long before anything more complicated than an amoeba has time to get going. Also, my assumption is that the levels of radiation a class-B would put out would be hell on any of its satellites.

    However our uber-aliens, with the amazingly high level of technology, might look at a class-B star and think: If we're smart we should be able to harness all that power for a few million years." After a few million years our uber-aliens are going to have to be elsewhere when the class-B goes nova. But anyone who has the know-how to build a Dyson Sphere has the know-how to be elsewhere when the house goes up.

    The beauty of a Dyson Sphere to Freeman Dyson was that it would utilize all the energy of a star. the beauty of our uber-aliens system is that they utilize the energy of their Class-B star twice: once in the filter which deals with the more energetic and dangerous forms of radiation, and once with the lower forms of radiation that has been put through the filter. This lower form of radiation would be akin to the energy output of Sol: of the spectrum and intensity that created life on Earth. The lower intensity radiation would fall on all that real estate beyond the filter and be used to produce food and energy of the sort we would utilize solar cells to harvest.

    It's a wonderful scenario--assuming I haven't screwed up anything. That's why I'm laying this all out for you really smart people; so you can tell me where I screwed up!
  12. Aug 18, 2016 #11
    Now I want to write The Spheres of Infinity.

    Or maybe not. Too many book unfinished already.
  13. Aug 18, 2016 #12
    I hear you Brother.
  14. Aug 19, 2016 #13


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    Here's a slight twist. Conceive a sphere that is not intended to support life, but instead intended to step-down the energy-density gradient (or thermal gradient maybe) of the high energy star to something directly useable by myriad less-robust equipment. The inside of the sphere contains the energy of the star, the outside of the sphere has tap points for other equipment to connect to, and these tap points provide (for example) a 1000C temp surface that can be used to drive a steam engine, if one wants to envision a steam-age society that was gifted with a long-lived battery. Or it provides some more advanced energy tap point that a star-faring craft could use to re-fuel. Like gas stations.
  15. Aug 19, 2016 #14
    Gonna need some way to keep them on the outside of the sphere?
  16. Aug 19, 2016 #15


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    In the steam punk scenario? Domes, maybe, if the sphere is spinning. They live on the "top" of the dome, and their "sun" is a hotspot on the surface of the Dyson sphere.
  17. Aug 19, 2016 #16
    Or a Ringworld "bolted" to the outside?
  18. Aug 19, 2016 #17


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    Formed to look like a steam locomotive from afar ... ;-)
  19. Aug 19, 2016 #18
    That would look LOCOmotive.
  20. Aug 19, 2016 #19
    I would be interested in reading that story.

    Dyson Spheres are like Black Holes. Everyone can write a story about them, and every story will be different. If anything each story will be more different. No one builds Black Holes.
  21. Aug 19, 2016 #20
    Never been to Calcutta?
  22. Aug 19, 2016 #21

    Well okay...there is one exception.
  23. Aug 26, 2016 #22
    Noisy Rhysling already addressed the main issue in his first reply: The technological requirements for Dyson Spheres would make them obsolete. But there are still motivations to build such a structure, e.g. as a message for everybody else: WE HAVE BALLS!
  24. Aug 26, 2016 #23
    Now I'm see a celestial hamster rolling around the galaxy.

    Thanks, that's cheaper than ... Um, never mind.
  25. Aug 26, 2016 #24
    That might be a better reason than all the practical ones.
  26. Aug 26, 2016 #25
    Super science doesn't mean super savoir faire. :-p
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