Rogue Rings

[Bear]

Strictly speaking neither tensile strength nor compressive strength in excessive amounts would be necessary for the structure to exist in a meta-stable state.  

You could have such a ring made entirely of liquid, and it would be stable until something made a splash or a wave, and started the whole chaotic cascade that would end up, in following decades and centuries, in the whole thing coalescing into separate bodies ranging from planet-sized to black hole, many of them on collision courses with many of the others, and more than a few about to be ejected in random directions from the site.

You need active management of some kind to stop that from happening; a network of maglev tracks running around the thing might keep masses actively moving to maintain balance, concentrate mass where needed for gravitational adjustments, and, via momentum, lend some local rigidity to the structure.   This is one of those things that requires minimal energy if done to absolute perfection, but would be extraordinarily hard to do to absolute perfection.

With some magmatter supporting the track, or providing local rigidity to prevent certain kinds of collapse or imbalance, it would get easier.  As a practical matter, some magmatter would be used.  But it's hard to say exactly how much, because we're talking 'safety margin' here - if active management is done to perfection, it's not needed at all.  The question is how close to perfection can it be done?

[Drashner1]

Apropos of nearly nothing, has anyone thought seriously about whether something like a 'grazer' could harvest material from a neutron star?  Could such a thing exist?

'Neutrons' aren't atoms, strictly speaking; liberated from the context of a neutron star, they'd do some pretty energetic things on the way to a renewed existence as baryonic matter.  

I ask because of the transmutation question raised earlier w/r/t stellar grazers, where Hydrogen and (especially) Helium aren't particularly useful as construction materials.  Neutrons lack an atomic number altogether. I don't even know what forces would govern the choice of what elements they eventually become as baryonic matter.

In principle, yes a grazer could take a neutron star apart if the grazer itself were sufficiently massive so that it could:

a) Get close to the star without itself being destabilized due to asymptotic flatness requirements. IIRC a mass as little as 1% of the wormhole mass can destabilize it, although I don't recall if we explicitly say that Y11k stabilization tech can overcome that limit or not. If not, then the grazer would need to be well over 100x as massive as the neutron star. Note however, that this same thing applies to any star a grazer is being used to take apart - either the archai need to be good enough at stabilizing it to let it come into proximity to more than 1% of its mass or the grazer (actually the 'entrance' mouth) must be many many times more massive than the star. If that works out to 80 or 95x more massive than the star, that's certainly a big improvement - but it's still a huge amount of mass energy. Although you can - in principle - extract it and shrink the overall grazer in the process, perhaps converting the energy into something else while your at it. Maybe amat - which you could then throw thru a Q-mirror and convert to regular matter. Hmm.

b) Tear the neutron star apart against it's own gravity.

As far as what you might get out of neutrons or H2 and He - The internal tidal forces of the grazer are huge - but I don't recall us ever nailing down how huge. But at the least anything passing through will likely be reduced to sub-atomic particles and maybe down to the constituent quarks and whatnot. If the latter - and since we're talking at least S5 godtech to make this thing - it might be doable for the archailect to manipulate the resulting plasma such that it reconstitutes back into heavier elements in whatever proportions are desired. At least I can't think of any reason why you couldn't do that unless there's something in symmetry or conservation laws that would impose limits of some kind.

Worst case scenario you can get it all back as H2 and then have to run it through a bunch of DWIZ to convert it to heavier elements.

Hope this helps,

Todd

[Drashner1]

Strictly speaking neither tensile strength nor compressive strength in excessive amounts would be necessary for the structure to exist in a meta-stable state.  

You could have such a ring made entirely of liquid, and it would be stable until something made a splash or a wave, and started the whole chaotic cascade that would end up, in following decades and centuries, in the whole thing coalescing into separate bodies ranging from planet-sized to black hole, many of them on collision courses with many of the others, and more than a few about to be ejected in random directions from the site.

You need active management of some kind to stop that from happening; a network of maglev tracks running around the thing might keep masses actively moving to maintain balance, concentrate mass where needed for gravitational adjustments, and, via momentum, lend some local rigidity to the structure.   This is one of those things that requires minimal energy if done to absolute perfection, but would be extraordinarily hard to do to absolute perfection.

With some magmatter supporting the track, or providing local rigidity to prevent certain kinds of collapse or imbalance, it would get easier.  As a practical matter, some magmatter would be used.  But it's hard to say exactly how much, because we're talking 'safety margin' here - if active management is done to perfection, it's not needed at all.  The question is how close to perfection can it be done?

Given that we explicitly describe Niven Clouds in the setting - as well as a topopolis filled with/made from water - it seems likely that Terragens are already experienced at stabilizing large ring shaped structures against their tendency to self-gravitate into a mess. On the flip side, given that we explicitly describe Banks Orbitals, World Rings, and Ringworlds as existing in the setting (and name a number of the former) we can also presume that magmatter as a source of tensile strength for large spinning structures is also routine. In the case of this structure it is the sheer size that is unusual, not the basic methods (assuming that scaling up this large doesn't take you into some new regime of instability challenges or the like (which it might but which we can't really say much about either as a practical matter).

I would expect that there would be some combination of active stabilization and magmatter supports in use (possibly along with other design elements), each most likely capable of holding things together on their own for some time simply as a matter of redundancy/safety.

Todd

[stevebowers]

Remember as well that a DWIZ does emit a lot of energy - transmutation up to iron is exothermic. Sure, you can use some of this waste heat to power processes, but there will always be a lot of waste heat at the end of the process.

[Drashner1]

Remember as well that a DWIZ does emit a lot of energy - transmutation up to iron is exothermic. Sure, you can use some of this waste heat to power processes, but there will always be a lot of waste heat at the end of the process.

Quite true - you don't want to cook/irradiate nearby star systems while creating this or any other large construct.

That said - an extended construction time of hundreds or thousands of years will help. And things like Matrioshka shells to get the waste energy to do useful work. And - possibly - you could set up one or more good size black holes in the vicinity and use them as 'ultimate heat sinks'. The more energy you dump into them the bigger they get and the better they work, pretty much w/o limit. We kicked this last idea around a bit in connection with S5 minds some time back but it didn't fully gel.

Not saying that the above methods alone are guaranteed to do the job - we need to run some numbers around this to get an idea of the size and shape of this particular elephant. But they do indicate there are various potential methods that might be used to bring waste energy levels down to some form of 'acceptable' (depending on how one defines that term).

Todd

[stevebowers]

I'm still puzzled about the high mass of this structure. If it is an S4 brain with a thin coating of habitability on (or near) the outside, wouldn't a Jupiter-mass (or thereabouts) be adequate?

[selden]

Perhaps you’re looking at the construct from the wrong point of view. Think of it as being an end in itself for the OA people responsible for its design and construction. By which I mean perhaps they intend it to be something analogous to a piece of art, not an object with a specific use case in mind. If someone in the OA universe were to find a practical use for it, so much the better. Or perhaps even maybe not, if the designer really was intending it to be a type of folly.

[Drashner1]

I'm still puzzled about the high mass of this structure. If it is an S4 brain with a thin coating of habitability on (or near) the outside, wouldn't a Jupiter-mass (or thereabouts) be adequate?

Agreed that in purely practical terms you only need a Jupiter brain (and equivalent mass - call it several hundreds Earth masses) to create a self-ascended S4. If the project is supported by an S5 or higher (and if that support includes the creation of the onboard S4), it could be even less as more advanced plasma processors or other computronium is employed.

However, also agreed with Selden that this project likely has more to do with creating a big habitat/structure than with actually producing a housing for an S4 (for which it is massively oversize). So the S4 is the onboard overseer rather than an end in itself.

Having said all that - I do think we should give some additional thought as to why this structure is being built/contemplated by Terragens. 5 million times the surface area of Earth is just a middling size habitat by Y11k standards. Places like Kiyoshi or Kepleria dwarf it in terms of habitable area and could readily replicate the environment if that was desired. A ringworld (1AU radius, roughly 1 million km wide) would be nearly as large and require only a fraction of the mass being used.

So what is it being built for?

Yes, we do have the MPA (and probably smaller groups scattered around) who like to build huge megastructures as art or for the challenge or for fun or the like. But in terms of raw living area (as described so far) this structure is not that impressive. Building a big habitable structure in deep space is also honestly not a big deal for a civ that has conversion tech readily available. Artificial illumination would be trivial with such tech.

Not arguing against doing this per se - but I think we need to come up with some larger purpose than just 'because we can' as a reason for why some group in the setting would construct this thing. For example:

We say that Terragens have attempted/are attempting some number of intergalactic expeditions or long range missions within our own galaxy (to galactic center for example). The relevant articles are all old and all make a point of saying the odds are not deemed good that the mission will succeed - but we can tweak that if we want. So - maybe this thing is an attempt to cross intergalactic space? To the Magellanics or maybe even Andromeda? Or maybe it's a form of 'deep time habitat' - intended to operate in the cold and dark of deep space while a slow living IR focused ecology lives on it and maybe while some number of sophonts slumber within it in stasis or as slow running uploads? Something else?

My 2c worth,

Todd

[selden]

From an in-OA viewpoint, if someone else can justify something like the Leviatham, why can’t (shouldn’t ? ) we? Especially if it heads toward a target that’s near the plane of the galaxy, by the time it leaves Terragen space, it’ll be able to accommodate “all the most recent” technological and societal advances appropriate for a successful trans-universal flight. Of course, the phrase “all the most recent” is a simplification for “successfully attracting support from the highest possible transophic.” Perhaps providing long term storage for the widest possible sampling of Terragen societies would be part of the project.

[Bear]

Hm.  I may misremember what toposophic level I was contemplating, but I did start by looking at the "sheer size of higher toposophic minds" when I was looking to see how large it needed to be.  

As said though, that's in the context of a story I don't seem to be writing at present; if this is a thing you want to see in the setting, it needs to be attached to a different story.

All told, it's considerably less convenient than a lot of other kinds of habitat; the aforementioned ringworld at 1 AU for example doesn't have any places separted by more than 250 million km. It's a few days of travel by high-speed maglev, at most.  

The Rogue Ring, on the other fist, has places separated by overland distances of about a hundred AU.  That's at least months of travel, even by high-speed maglev.

Also, I'm going to repeat that outside the context of that story, there's no mandate that a Rogue Ring should be any particular size. Somebody demonstrating the concept could do so by building something a tenth of that size or less, and it would still be a remarkable instance of an ISO type not previously built.