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Life on a Culture Orbital

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  • 17-10-2007 9:03pm
    #1
    fly_agaric
    Registered Users Posts: 4,890 ✭✭✭


    Maybe I should take this to the Science or Physics forum but, anyways...

    I've read a number of Iain M. Bank's Culture books.
    In these Orbitals are mentioned.

    Orbitals are apparently a big ring orbiting a star (but not with the star at the centre like a dyson sphere or a segment of a dyson sphere).
    An Orbital would be maybe 1000000km across and would rotate according to the books at a rate that would give both 1g artificial gravity on the inner surface of the ring and a day-night cycle of 1 day (how convenient)....
    However when I look at these numbers I think there is no way that can be right. If the thing rotates in a day, the radius is so big that apparent g at the surface will be much larger than 10 m s-2. Taking into account the mass of the stuff the orbital is made of would just make things worse (even though the books imply that the orbital doesn't have much gravity becuase it is not very thick...).

    Could someone tell me if I am misremembering physics here or if I am correct??? Or if I should stop thinking about this for the benefit of my sanity.:(


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    #2
    ixoy
    Moderators, Entertainment Moderators Posts: 17,991 Mod ✭✭✭✭ixoy


    Doesn't Mr. Banks though place the Culture in such an advanced position, technology wise, that he doesn't have to worry about explaining its workings? I thought that was his position, so as to enable him to focus more on twisting plots and characters.
    Current favourite balance for science and fiction elements: Alastair Reynolds (really liked "Pushing Ice").


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    #3
    fly_agaric
    Registered Users Posts: 4,890 ✭✭✭fly_agaric


    I feel like a total idiot for posting this thread now.
    Was messing around later and the calculations in the books for an Orbital are correct...
    a = 10 m s-2; r = 1000 m/km*1e6km
    w = SQRT(a/r) = 1e-4 rad/s
    1rad = 1/2pi revolutions
    1day = 86400s
    giving 1.3 revolutions/day (...I think)
    ixoy wrote: »
    Doesn't Mr. Banks though place the Culture in such an advanced position, technology wise, that he doesn't have to worry about explaining its workings?

    Yes. Full of star trek sort of stuff, but it bugged me that something small like that involving very fundamental/basic physics could be wrong. Should have known it was more likely I was wrong...
    ixoy wrote: »
    I thought that was his position, so as to enable him to focus more on twisting plots and characters.
    Current favourite balance for science and fiction elements: Alastair Reynolds (really liked "Pushing Ice").

    Thanks for the suggestion.


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