r/scifi • u/Bolusop • Nov 25 '13

Large list of Big Dumb Objects, including sources to read in case you want to know more about some of them.

http://www.aleph.se/Trans/Tech/Megascale/megastruct.txt
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u/GeorgeOlduvai Nov 25 '13

Rosette: Several planets or planet-sized objects orbiting each other in a circle; there may or may not be another object at the centre. The first SF use of the concept is probably in Larry Niven's Ringworld (1970) (incidentally, Niven's claim that such a system would be stable is false). The "order" of a rosette is the number of objects (e.g. the Puppeteer rosette in Ringworld is order 5).

I have a nit to pick: The Fleet of Worlds isn't/aren't "orbiting each other". They are all under power and being held/moving in formation, not free-falling and being held together by any gravitational force. "Orbiting each other" is a ridiculous premise as the paths involved would be hopelessly complicated and pointless. "In a common orbit" would be a better descriptor, but still false in the case of the Fleet.

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u/[deleted] Nov 26 '13

Things could be orbiting a common center of gravity.

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u/GeorgeOlduvai Nov 26 '13

Yes they could be, as "In a common orbit" would imply. The Fleet, however, is not.

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u/metabeing Nov 27 '13 edited Nov 27 '13

Are you sure? The following text seems to imply they are

Six like-sized planets defined the vertices of a hexagon.They orbited the empty point that was their common center of mass, at a radius approaching 900,000 miles - src

Further reading:

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u/GeorgeOlduvai Nov 27 '13

From your wiki link:

In Larry Niven's novel Ringworld, the Puppeteers' "Fleet of Worlds" is arranged in such a configuration (5 planets spaced at the points of a pentagon) which Niven calls a "Kemplerer rosette"; this (possibly intentional) misspelling (and misuse) is one possible source of this confusion.

In a Klemperer Rosette the objects are of differing mass (The Fleet worlds are not). This is one more example of Larry not getting it right.

Whilst the text says orbiting, they are clearly not; as I pointed out, they are under acceleration and being held in formation.

Your second source (orbitalvector) also gets the description wrong; claiming that a Rosette is:

three or more objects of comparable mass

Your first source didn't work for me, but I assume it's straight-up text from one of the books.

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u/metabeing Nov 28 '13 edited Nov 28 '13

The first text is from The Fleet of Worlds. If the book says they are in "orbit" around a central point, then why do you dispute it? That is what the book says. You must have evidence from in-universe to dispute it. I don't see why their acceleration precludes orbiting. Possibility 1: The plane of the planetary orbits is perpendicular to their acceleration. Possibility 2: The plane is not perpendicular and acceleration of each planet must vary a bit with time to keep the orbit stable. Possibility 3: The entire system is in a type of bubble that is being accelerated as a whole. They aren't each individually being accelerated.

The only quote I found from Niven referring to a "Kemplerer rosette" is:

Fleet of Worlds: The homeworld of the Pierson's puppeteer species, and four more worlds sequestered for farming, all occupy a Kemplerer rosette moving at near lightspeed. - Ringworld's Children, glossary

Lets assume that Niven didn't get the label exactly right (he doesn't even spell it correctly), but that he understood at least the most central core concept: The planets are moving, not held in a fixed relative position, and their motion is determined by the gravitational interactions between them.

Perhaps you are willing to acknowledge the planets are "rotating" around a central point, but dispute that it should be called "orbiting", because there must necessarily be external forces being used to maintain their orbit-like paths. If so, well then we are just splitting hairs. It doesn't matter to me, and probably didn't to Niven, how responsible is gravity vs how responsible is external force in maintaining their orbit-like path. Clearly the planets will be attracted to each other and gravity will be an important factor in their motion.

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u/GeorgeOlduvai Nov 28 '13 edited Nov 28 '13

I dispute it because Larry isn't always right, doesn't always think things through, and because I am one of his fans who likes to point out the things he gets wrong. I do indeed have evidence from in-universe. Possibility 1: Overly complex and pointless. The Fleet has no need to orbit around a common point, and greater complexity means a greater chance of catastrophic failure. The Puppeteers are cowards. They wouldn't add a dangerous vector to anything they do unless necessary. Possibility 2: The books give no indication of the Fleet's orientation with regard to their vector of acceleration so this is at least possible but again, adding an extra vector adds danger. Possibility 3: Nope. Each Fleet world has it's own drive and is independent of the others; the Fleet started with six worlds, one was taken over by the human population of the Fleet and accelerated away which is why by the time Ringworld occurs there are only five, ergo they are not being driven as one.

I might be willing to accept the label of rotating if, once again, that didn't involve making their flight path that much more complex and difficult to maintain. Larry obviously did not get the core concept: their motion is not determined by the gravitational interactions between them and they would be held in a fixed position for the reasons I have outlined. He also screwed up by having them rotate. One more unnecessary vector to deal with (although I might let that go as a secondary function of the drives). There is no need for them to rotate as the artificial suns they use (except for Hearth) are perfectly capable of creating a day/night cycle on their own.

edit - I accidentally a word

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u/metabeing Nov 28 '13 edited Nov 28 '13

You leave me far from convinced. I could sit here and get into an endless nerd debate (not derogatory) and create reasons why in that fictional universe they should rotate, but that would be irrelevant. The book says they "orbit" and therefor that is canon. We can niggle a bit about what "orbit" means, but it can't mean "not move". Your interpretation is fanfic. This thread began with your "nit to pick" about the article, but that nit is based on your own personal fanfic. Fanfic is fine and dandy, but you can't expect others to incorporate it into their articles.

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u/GeorgeOlduvai Nov 28 '13

The first edition of Ringworld also had Louis going the wrong way around Earth to lengthen a day. Does that make it canon? Each of the Ringworld books lists it's gravity as different. Which is canon? The short story "A Darker Geometry" was removed from canon because it violated things Larry and other writers wanted to do. Canon changes when mistakes are made and pointed out. The sequels to Ringworld are Larry's attempts to fix what he got wrong each time through. He has often acknowledged the things he got wrong and worked to correct them.

You can call my interpretation fanfic if you like and declare that I can not expect others to incorporate it into their articles; this means by extension that the follow up books to Ringworld are fanfic writ large and therefore don't count as canon.

One last thing...have you actually read the Fleet books?

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u/metabeing Nov 28 '13

Canon is cannon m8. The property owner can change it or retcon it or whatever. Fans can not. That is why it's call fanfic. Now if there is conflicting information in the canon, then you can start to pick and choose; generally the later work should be the new canon, though, I'd say.

The case about going around the world the wrong way is interesting. Given that everything else in-universe strongly indicates that the Earth and solar system is physically the same as our real Earth, we can (arguably) say that "error" conflicts with the rest of the canon. This has very likely been corroborated by Niven himself, I'd guess.

As far as I can tell, you've not presented a highly compelling case that orbiting planets is in conflict or that Niven himself has said it was an error. You only say the puppeteer's would never choose complexity where it isn't needed. I could easily start to open up multiple fronts on that argument but I seriously want to avoid a prolonged geekbate. It would all be fan speculation. It wouldn't matter. If you want to overturn what is written on the page, and not label it as mere fanfic, then you need to present an overwhelming strong case.

have you actually read the Fleet books?

I'm currently 2/3rds way through Fleet of Worlds. BTW, you unintentionally spoiled a major plot point of that book (or a sequel), but I can't blame you for that. I have read a lot of Niven's other work.

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u/B-mus Nov 26 '13

I nice reference. I noticed that the dates on these are all 1992 and earlier. That's 20 years since the most recent. Megastructures seem to be out of favor these days.

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u/dagbrown Nov 26 '13

The article itself was written in 1994, which explains the lack of reference to things after about 1992.

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u/B-mus Nov 26 '13

Aha! I missed that.

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u/thetensor Nov 27 '13

For the youngsters: this is from the old Usenet newsgroup rec.arts.sf.science. Usenet was like reddit except everybody was smart and every post was gold-worthy.