Author Topic: The smoke ring (just like the ringworld) is unstable!  (Read 1027 times)

Offline Fourdoor

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First let me say that the Integral Trees, and The Smoke Ring are wonderful books by author Larry Niven, and I enjoyed reading them over and over again... but the physics and orbital mechanics don't work with the description and storyline.

For those not familiar, the smoke ring is a habitable zero G open environment created by a gas giant (Goldblatt's world, shortened to "Gold") in a very close orbit around a neutron star (Levoy's Star, shortened to "Voy") that is orbiting a Sol like G type star (called "the Sun").  A billion plus years ago, the gas giant was torn asunder by tidal forces creating a gas torus where in "present time" in the story the densest region of the gas torus is at around 12 or 13 psi.  This region evolved life and is inhabited by the decedents of the crew of a seeder ram ship.

Anyway, our protagonists are living on a dying integral tree.  It is dying because it was moved into an orbit much closer to Voy where the air, water, and other mass is much less dense.  This was due to gravitational effects from a close pass by Gold.   The following orbital periods are based on the story description of how long a "day" is, and the definition of a day in the story.  At this new location the tree has an orbital period around Voy of 2 hours.  The densest zone of the life bearing region of the torus (the smoke ring) has an orbital period around Voy of 8 hours.  The problem is, our author treats the location of Gold as static in relation to the dying integral tree, it is described as a vast storm system to the east (orbital direction).  An overhead view diagram of the system shows Gold, and the L4 and L5 "clumps" as being in the center of the smoke ring, so they should have an orbital period of 8 hours.  Now, if your protagonist location has an orbital period of 2 hours, and the dense part of the smoke ring has an orbital period of 8 hours, you would go whipping past everything in the dense area around every 6 hours... it would not be static in relation to you.

Other diagrams in the book showing the cross section of the gas torus show Gold as being towards the inner edge of the smoke ring rather than the center... but that would still be the densest part of the smoke ring, just a different perspective in the drawing.

Long story short, the smoke ring description of how gases work in the smoke ring and gas torus (gas molecules in orbit around Voy that when perturbed by gravity from Gold are sent inward or outward from the dense region and replaced by more gases escaping from Gold) would also apply to liquids and solids.  This would make the smoke ring a churning mass of chaos and destruction rather than a stable habitable zero G paradise.   Being just a slight distance inward or outward from Gold puts you into a vastly shorter or longer orbital period where you would (if inward) whip past Gold several times a day, or if outward have Gold whip past you several times a day.  This would continuously cause gravitational disturbances ejecting solid and liquid mass inwards and outwards from the smoke ring... life might exist but I find complex life hard to believe.

This is all based on descriptions in the books (2 hour orbit at inner edge of smoke ring, 8 hour orbit at middle of smoke ring), I have not done orbital calculations myself.   

I can't be the first to notice this, but I haven't found it discussed elsewhere.  The ringworld stability problem was discovered by engineering students and brought to Nivens attention and resolved in the sequel to ringworld.

Thoughts?

Keith
« Last Edit: 10/23/2024 01:09 pm by Fourdoor »

Offline Twark_Main

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Re: The smoke ring (just like the ringworld) is unstable!
« Reply #1 on: 10/28/2024 04:43 pm »
As an aside, I've never understood the evolutionary botany of integral trees. It seems far more beneficial to grow structures that cling to and retain a glob of water, rather than growing many kilometers long just so you can optimize for harvesting wind-blown debris at the tufts. I don't see how integral trees could possible complete with... uh...  water-blob trees.  :-\


Though I suppose that's largely the same as what you're saying: in the real world stuff would "want" to cling together into larger units...

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