A pendulum uses gravity as its source of energy, much like a hydro-electric dam.
close but not quite right. a pendulum uses gravity to convert energy back and forth between potential and kinetic, the source of energy is whatever originally positioned the mass above a gravity well. in a hydro-electric dam this source of energy is the sun evaporating water from a lower region (which then condenses above the dam).
Very true. Point conceded.
the device you describe would require a constant input of energy to counteract friction. it is one of those clever devices mentioned in the story which successfully refills a tank but requires more than a tank's worth of energy to do it.
and, in order to have any chance of working, the world must resemble an infinity tall cylinder of chromium that's wide enough to accommodate the swing of a pendulum so large that it dips into an argon atmosphere so deep that the ground level compression is substantial. nevermind questions of how gravity generated in such a bizarre universe.
Well. Yes.
I just couldn't think of any other possible way to deal with argon. Noble gas, no known solid state, liquid only at an obnoxiously low temp. It's too stable for even fusion or fission to do much with it.
My mental image was based on liquids really. If you had two diving bells on a pulley system, both filled with water, and sunk one to the depths, it weighs no more than the other one. As you hoist it up, you send the other down. Requires very little energy. But now that first diving bell has an incredible amount of pressure inside it, enough that I'm betting it would be more energy than the cost of pulling it up while sending its counter-balance down. Strictly speaking, it's not a perpetual motion machine. It is using an external force (gravity) to do work. The devil is in the details of course. The energy used to construct the vessel and the stresses it would endure mean you might not really get the total energy put into it back out. We lack sufficient info on the specifics of their world to easily say.
But you are right. A universe with the right constraints for it to have a snowball's chance in Hell of working is very low.
a much more likely explanation is that these are remarkably small entities instead of the container being enormous.
Careful! A tiny universe comes with its own set of problems. Friction is the nemesis of nanomachines. Also, given pendulums work as a moment-to-moment measurement of time that either their world is scaled to them OR it exists in some larger world. A tiny world alone in the void is no different from a very large world alone in the void. If it exists in some larger world, external forces are acting upon it and that means the potential for energy from outside the system, and that gives them a definite possibility of escaping their fate. (Note: The argon from the other chamber may or may not be evidence of an external system)
Hm. Though I suppose the existence of gravity almost requires there be an external system of some kind. I mean...
Think about it. If they were a universe alone in a void of nothingness, the most concentrated point of mass in their world would be the bottom of their gravity well, yet all the mass in their universe is in contact with itself, so it would collapse in on itself, becoming infinitely dense and ceasing because once everything in universe is at the same point, gravity becomes unmeasurable. It effectively ceases to exist.
.Unless, of course, the structure of the shell were solid enough to somehow hold that force in check. But then you've got all sorts of unfathomable problems. If the central mass is attached to the shell, the warping of spacetime would be such it would eventually be the same as a single-point universe. If the central mass were unattached to the hull, it boggles the mind really. Assuming the central mass holds itself coherent and the shell is also coherent, then... Wow. That will make your brain hurt. It seems like there'd be a force almost like tension being generated, but where would it come from and how could you define it? Augh.
Anyhow... I got way off in left field. So.. I think we both agree that their world must exist inside a larger universe. (whether that makes US flatworlders or not is a separate debate) I further submit that IF their world exists in a larger universe, there are external forces acting on their world. Given that, no matter how slim the odds are, there exists the potential for them to use one of those external forces to escape their fate.
I suppose the same applies for heat death of the universe. In order for time to begin or end, there must be something outside it. Of course, from our POV, it would imply there's something outside that too and so on and so on. But that's probably a limitation of us. We live in 3D space, fixed in time. Our eyes map this 3D world onto 2 dimensions. If we truly saw things in 3D, we'd all be able to see what was sitting on the other side of the wall from our current vantage point.
