- rolls eyes - in an appropriately christmassy manner*
Yes, that one. I've been referring to those as clusters because of the similarity to real Globular Clusters. A real solar system is something like a million times as big (in diameter) as a planet. Much less, similar to, or much more than that?
Things could live in the galacier. Ice behaves like a liquid, just not on human timescales. A really really slow fish could swim through ice like a normal fish does through water.
The stars could be the egg-stage of that galacial life, the heat and vargity could be the waste products of the developmental processes happening inside, and the "twinkling" could be the embryonic heartbeats. If seconds become days, then nine months become billions of years (no, not really, but it goes in the right direction). That may not make the world "Immortal" enough, though.
Alternatively, the stars could be the products of a biological version of the Big Bang. They weren't there, and then they were, and you're not allowed to ask questions because time didn't exist before then anyway, and all that sort of thing. 
The stars could be the egg-stage of that galacial life, the heat and vargity could be the waste products of the developmental processes happening inside, and the "twinkling" could be the embryonic heartbeats. If seconds become days, then nine months become billions of years (no, not really, but it goes in the right direction). That may not make the world "Immortal" enough, though.
A creature that swims through the ice is one possibility, but another is a creature that burns a path through the ice. I'm picturing an enormous, serpent-type Eastern dragon.
And don't worry about the name, it's still immortal compared to humanity, and the inevitable end of the universe fits in with the theme of mortality nicely. Furthermore, the cycle will begin anew somewhere else. Besides, it's not to late for me to change my mind about the name, all that's lost is $11 on the domain name, and I've already wasted that much, so what's another $11. Anyone want to buy flyorfry.com? (What was I smoking when I thought that would be a good name?)
Even if ice does act like a liquid (which I didn't know), it probably doesn't at absolute zero, right? So both galacial monster possibilities suggest there's something outside the galacier, either as the origin of the tunneler, or a source of heat for the ice swimmer to evolve. Not that it matters, since this would be so far outside of human experience as to be irrelevant to most stories.
edited 7th Oct '12 9:24:11 PM by Topazan
I was asking because if the cluster is that big, and you want physical principles to basically apply, as you said earlier, then you can't have ordinary gravity operating in addition to the stellar repulsion. That's the scale at which gas clouds, of which the totality of the Aerosphere is clearly an instance, turn from being pressure-dominated to being gravity-dominated. Meaning, in the long run the thing would begin to collapse into a planetary nebula, which in turn would eventually give birth to an ordinary solar system with most of the matter assembled into the central object or objects, i.e. the star or binary.
And if there is no gravity, then you can't have self-assembling planets or black-holey things in the dead zones.
Three obvious solutions - make the cluster much smaller than that, ignore the physics, or just go with the lack of gravity.
Oh, of course. The astronomical force-based equivalent of the hard shell, basically. Nice one. 
Any kind of big worm that moves through something solid will inevitably invite comparisons to Shai Hulud, though. If it's melting the ice anyway, it doesn't have to be quite that streamlined, and you could go with a different kind of animal.
A viscous fluid might be the technically more appropriate term. If you had a video recording of the advance of a glacier over millions of years, it would look indistinguishable from flowing lava, or from trickle of honey flowing down an uneven slope. Just a question of scaling.
Glass works that way too, which I found even more surprising when I learned it. The solid-seeming panes of glass in your windows are actually veeery slowly trying to become puddles on your window sills. The relative increase in thickness near the bottom compared to near the top, as they assume a more drop-like shape, can even be perceived with the naked eye in windows that are sufficiently old - or so I've been led to believe, anyway. Weird, huh?
I dunno what would happen near absolute zero. Your suspicion may be on target, or it may not, or there may be some funky supersomething (superconductivity, superfluidity, that sort of thing) effect starting to happen before one gets there. Even if it doesn't melt it all the way, the body-heat of any ice swimmer would surely warm its immediate environment sufficiently for that not to matter much either way, though, it seems to me.
Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
Oh, okay. That doesn't work at all.
It's just not how physical forces work: Repulsions from, in the simplest case, two opposite directions with equal magnitude simply cancel out, rather than causing compression. Just as, when you are in orbit about the Earth, downwards gravity and upwards centrifugal acceleration cancel out and leave you weightless, instead of giving you the feeling of being stretched on a rack between them.
For compression, the repulsion would have to be not so much a physical force as the result of, basically, a really strong solar wind which pushes everything it encounters away from each star. But that's going to be a nightmare in any remotely physically consistent treatment, so I'm going to recommend strongly against it at this point.
It's definitely real in principle, because old-style large telescope mirrors have to take surface deformation due to glass flow into account. I can't see any plausible reason for it not to happen in ordinary things like windows, but it's entirely possible that the "visible to the naked eye" bit is a wild exaggeration, yes.
Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
Hm, so in the absence of gravity, what would happen to solid objects in these dead zones? I would have thought that the point in which all stellar forces are perfectly balanced would be tiny, and everything around would fall towards this point. More objects would mean more weight upon the whole structure.
By the way, wouldn't you need at least six stars to reach this equilibrium, not four?
In that sense, you are of course right that the force is compressive. I assume, however, that you want the vargity to be at most one gee in the habitable region, and that it is meant to fall off with the inverse square of the distance from the star, yes? If so, these dead-zone matter assemblies would have to grow to a radius at which their surface is closer to the habitable region than to the dead-zone itself before the net force becomes non-negligible.
If that is actually feasible, you might be on to something.
The tetrahedron is the simplest polygonal body in three dimensions. Thus, you have to choose at least for points in space to define a fifth point as their centre. With three points, you get a line, with two, a plane, with one - erm, it becomes a matter of definition, I suppose.
At the very least, the atmosphere would extend up and past the habitable zone, if it could be called that.
edited 10th Oct '12 10:04:14 PM by Topazan
Oh, okay. That brings us almost full circle back to the original setup, with diminutive skylands suspended at some distance over the solid surface of a planetary-ish body, except that now the thing that gives that planet its atmosphere is not its own gravity but the combined vargities of the neighbouring stars. Interesting.
Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
Hm, good point, and it leaves the problem of visibility. Maybe there should be another astronomic creature to clean up the dead space. Some analogue to black holes.
One difference is that one aerosphere has several planetary surfaces.
Oh, yeah, never thought of more than one dead-zone at once. Blimey, this is really difficult to properly envision. I like it! 
How about if the stars slowly drift about, relative to each other? Then, over astronomical timescales, I think your original notion that things would eventually end up stuck to the galacier wall would turn out to be true.
You'd just have to explain how the skylands can be stuck to a point in space which is fixed relative to their star but not fixed altogether, but that makes that aspect only marginally more implausible.
Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
That's a possibility. Or it could be that the vargity is slightly reduced during the dimming phase of a star, so over astronomical time periods, stuff gets shoved along as the center of the dead space shifts? Hm, may have to run a mathematical simulation to ensure that it wouldn't just keep going in circles.
That is a very lovely idea, but make sure you think through the implications with regards to what you want to actually focus on first. Should flight be easier by night than by day, et cetera?
Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
Ho, I just came across the wikipedia article that covers "island hopping". Have a look, if you haven't already: "Oceanic dispersal
"
Nice. Getting tangled in vegetation does make a lot more sense than balancing on a log for larger creatures, and it could be applicable to the setting, if there are slightly buoyant mats that get caught in the wind sometimes.
I liked the version with the leviathan better, actually. Maybe you could combine the two, by having the leviathan be covered in plant litter for some reason? Which, on second thought, would make them like mini-skylands, except mobile. Skyrafts. Maybe there's some deeper biological connection there. The analogy of bees flying from flower to flower suggests itself, but sponges don't need that kind of help with procreation (right?) so they'd have no incentive to offer a nectar-analog. Well, maybe you can glean something from that derailed train of thought anyway. :)
Soon the Cold One took flight, yielded Goddess and field to the victor: The Lord of the Light.
Definitely something to think about either way. Really, the important thing is non-fliers spread through rare events.
Oh, come on. Don't go casting doubt onto the title now.
j/k
"Immortal" because the seemingly eternal nature of the sky contrasts nicely with the fragile and ephemeral nature of human life and civilization in the setting. Also, it makes the acronym TIS, which lends itself to Christmas related puns.
Other names I considered: -Caelum Invictus - Rejected because I hadn't planned on a Romaneque civ playing any major role in any storylines. Also, bad juju from another game with a Latin name. I had high hopes for this game as a player, but it turned out awful. -Unconquered Sky - Makes an even better acronym (US vs them), come to think of it, why didn't I choose this name?
There were dozens of others, but mostly they were either not catchy enough, or catchy but meaningless. I didn't want to sound pretentious with the latter.
Of course, if we add in other dimensions, like how I alluded to with the sky sponges, then it opens up some possibilities...