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mathmancer
2014-10-02, 08:51 PM
Hello every one! Today I have another perversion of physics. This time I'm violating Thermodynamics to create a self perpetual motion devices, by using the bag of holding from dungeons & dragons.

Ever play Dwarf Fortress? It's a game that sets out to do no less than simulate all of reality itself. It does this using ascii based graphics no less.
It screws up on the conservation of mass and energy though. In the game you can make elaborate traps (just like those guys who make Turing Complete Machines in minecraft!), and some of them need "power". In this case, people found out that a water pump uses less energy than is generated by a water mill. A water pump connected to a watermill will not only be self perpetuating, but will generate surpluss energy you can use to turn the drive shafts connected to your grain mill, or your deathtraps. The Dwarf Fortress community calls this the "Dwarven Water Reactor"

Similarly, I've designed a d&d version that uses the bag of holding. The bag of holding ALWAYS weighs the same, no matter how much is in it.
There is a continuous bucket elevator, a water wheel, and two reservoirs (upper and lower). The outlet of the Upper reservoir turns the water wheel, and then all the water collects in the lower reservoir. The waterwheel turns an "output shaft" that drives machinery, and the continuous bucket elevator. The continuous bucket elevator carries water from the lower reservoir to the upper reservoir.

Photo 1.1 a real life continuous bucket elevator
http://www.marchantschmidt.com/sft529/main_14.jpg

The continuous bucket elevator is like a normal real life one... except the buckets are actually bags of holding. This means that the continuous bucket elevator will carry more water UP than it takes to turn the waterwheel (Take that Thermodynamics!). The continuous bucket elevator will still be efficient if you only have 1 bucket (if it's a bag of holding bucket. In this situation, adding additional normal buckets would only take MORE energy, because that's just extra weight to carry to the upper reservoir). Continuing the heritige of the Dwarven Water Reactor, I have the dwarves in my homebrew d&d games build these to power their machinery.

Diagram 1.1 the dwarven water reactor
http://i46.photobucket.com/albums/f145/mathmancer/waterreactor_zps743d4341.jpg

This isn't the only bag of holding abuse I've come up with. Rockets with infinite Delta-V are a favorite of mine, but you can combine the bag of holding with stuff like teleportation circles (especially permanent ones or 4e style ones), to break trade and logistics in the Tippyverse further. Just like in the Baldurs gate video game, a transporter could have a few dozen bags of holding in a normal backpack and carry enough supplies ON HIS PERSON to supply entire armies. Exactly how many bags of holding would be used in an army would probably depend on doctrine. One army may give each soldier a bag of holding full of weeks of supplies, while other armies may only give them to some one with accountability like an officer (or NCO depending on the "strength" of your NCO corps) who then distributes those supplies as needed. Ideally, every single guy would carry a bag full of supplies, but trustworthyness and projected combat losses will be the limiting factor.

A car, or military tactical vehicle, could have gas tanks built INTO a bag of holding to increase it's range. Actually, as this reduces the weight of the vehicle, it also improves mpg. You could do the same for trunk/storage space.
I didn't see this mentioned in the TIPPYVERSE thread, but I sort of assumed that bags of holding were commonly used to improve the indipendance of armies, as well as the throughput of trade. It would only AMPLIFY the effects that cause a tippyverse.
This is actually the first in a series of D&D based perpetual motion machines I plan on presenting. Others include abusing permanently animated objects, lightning traps, and the domestication of Thoqqua's.

Note: if you use a decanter of endless water to continuously fill the upper reservoir, you don't need the continuous bucket elevator.

ellindsey
2014-10-02, 09:46 PM
You can actually make a perpetual motion machine out of common brown mold. Brown mold maintains a constant cold temperature despite the surroundings. Ammonia is a gas at normal room temperature, but a liquid at the temperature of brown mold. Surround a tank of ammonia with brown mold and it will stay liquid. Let some of the ammonia flow out through a heat exchanger with the outside environment and it will turn to gas. Run the expanding gas through a turbine or piston engine to extract mechanical energy, and then let it flow through a heat exchanger surrounded by brown mold to return it to a liquid state. So long as the brown mold stays alive and contained and the ambient temperature heat exchanger stays warm enough to boil ammonia, the engine will keep running. And it even works in an anti-magic field, since a brown mold's cold-making power is Extraordinary, not Spell-like or Supernatural.

Steel Mirror
2014-10-02, 10:02 PM
While the water reactor as described could certainly work, it doesn't necessarily violate thermodynamics, at least not if we make some excuses based on other things we know from the D&D universe. If you look at other magical effects in the game, it is trivially easy to draw large amounts of energy from apparently nowhere; even an apprentice can do it with (assuming 3.x here) a number of cantrips that allow you to levitate small objects or create fire without the input of energy in any apparent way. Where does that energy come from?

Of course the answer (beyond just repeating "I should really just relax (http://tvtropes.org/pmwiki/pmwiki.php/Main/MST3KMantra)" to yourself 12 times under your breath) is that it is magic- that is, there exists some force that pervades the universe which can be tapped to accomplish work (in the physics sense) without needing to balance the equation here in meatspace. So the energy for your fireball isn't really created, it's just shunted from some parallel realm or invisible fabric of the universe or the souls of the damned, or however else magic works in your world. You seem to be violating the conservation of energy, but you're really just cheating by calling in energy from somewhere else.

The water reactor and any other perpetual motion machines made possible by magic could be said to work in the same way, by steadily drawing upon ambient magic (in whatever form that takes in your world) in order to accomplish work in the physical realm. That doesn't make it any less interesting to design these machines, if that's what you fancy, and you could certainly end up with a uniquely quirky setting where the denizens take full advantage of all these little loopholes in the physics of magic to create wonderfully cheeky contraptions. I look forward to seeing what you come up with! But if you want to have your magical engines and keep your thermodynamics too, there is a weasel way out that just expands the size of the system under consideration from "our physical world" to "our world plus whatever it is that makes magic happen".

And now I feel bad for killing all the catgirls, so I'm going to go watch some MST3K to atone for my sins as I wait to see what else you've got for us. :smalltongue:

ellindsey
2014-10-03, 12:29 PM
My solution was to declare that my game took place in a world with very different laws of physics. No relativity, no quantum mechanics, conservation of mass, energy and momentum are fairly easily broken, Aristotelian physics are mostly correct, the world is a flat disk and the sun and moon small bodies that sail overhead, etc. Then I worked out some implications of that and figured out how certain civilizations (expecially the Dwarves) had developed technology based on these different physical laws. It seems to fit better with the game rules and how they describe motion and energy, and helps me come up with consistent answers to questions like what happens when you teleport to the other side of the world, or how do underground civilizations survive and feed themselves.

Slipperychicken
2014-10-03, 04:39 PM
Wouldn't it would be more efficient to just enchant the wheel as an animated object, and command it to spin itself?

Ravens_cry
2014-10-03, 05:50 PM
Perhaps, but the size, and therefore Strength, and therefore torque, of an animated object depends on caster level, and a really big one will take up a lot of space. Also, Animate Objects is a sixth level spell, which means you'll need pretty plentiful high level casters to make this a part of your infrastructure.

ellindsey
2014-10-03, 06:23 PM
Animated objects can also be shut off by an anti magic field, and I think by dispel magic at well. There are ways to make perpetual motion machines by the rules that can't be so easily shut off.

The Pathfinder equipment book describes Dwarven Fire-forged Steel, which only conducts heat in one direction. This laughs in the face of Thermodynamics and makes perpetual motion machines easy to build.

Erik Vale
2014-10-03, 08:19 PM
The Pathfinder equipment book describes Dwarven Fire-forged Steel, which only conducts heat in one direction. This laughs in the face of Thermodynamics and makes perpetual motion machines easy to build.

It has the same for 'cold' [or is that the same in reverse, I'm not sure].

Ravens_cry
2014-10-03, 11:36 PM
It has the same for 'cold' [or is that the same in reverse, I'm not sure].

Frost forged steel, yes.

Slipperychicken
2014-10-03, 11:46 PM
Animated objects can also be shut off by an anti magic field, and I think by dispel magic at well. There are ways to make perpetual motion machines by the rules that can't be so easily shut off.

Well, the "animate objects" spell is a spell which can be dispelled or suppressed, but Animated Objects (as in the monster) are constructs and aren't subject to AMFs or dispel magic.

mathmancer
2014-10-05, 11:12 AM
actually, I have a lot more perpetual motion machines, I just wanted to put each in their own thread.

I thought about animated object once as a way to power robots and power armor and any other machinery or equipment that needed electricity. I was just going to have an alternator or generator and cast animate object at it, providing energy for the item. The advantage to do that, as apposed to just animating the armor or robot, is that you can freely swap parts in and out of the stuff as technology improves. You already payed more gold for the permanent animate object spell than some villages earn in a decade, you don't want all of that investment tied to a machine that will be obsolete in a year or less.

Lightning trap: just put a sandbag on the pressure plate after putting a lightning rod by the emitter. Tie the lightning rod into the grid and you have Free electricity for your home!

And finally, the THOQQUA reactor. A long while ago, the Soviet Union designed a subterine (that's a submarine that digs through the rock instead of the water. Essentially a drill tank). It worked by melting the rock ahead of it, and that required the energy of a nuclear reactor. The Thoqqua can do this. So I thought of putting Thoqqua in an enclosure surrounded by water, and then using the steam from that water to turn a turbine. Essentially, you'd have a traditional nuclear reactor that replaces its Uranium with a big monster.

diagram 2.1
http://i46.photobucket.com/albums/f145/mathmancer/thoqquareactor_zpsf558c51c.jpg

Naturally, it would generate less energy than a nuclear reactor, since the thoqqua only creates an amount of energy (in heat) equal to what you get AFTER spending the energy from a nuclear reactor to power something. And then you have loss as you try to convert that heat into electricity. But since your energy source never runs out, and didn't take as much energy to create, it has over 100% efficiency (raising a thoqqua from birth would take less than what is required to CREATE Uranium. In real life, we only dig up uranium and refine it).

Other issues are feeding or paying the thoqqua, and that it needs to take breaks. Still, none of those are such enormous issues. You've the output of a nuclear reactor. You can afford to pay/feed your employees/livestock (I'm not sure how smart a Thoqqua is).

The brown mold idea that ellindsey came up with is brilliant too (and similar to the thoqqua in many ways)

Steel Mirror brought up the cat girls again, and also talked about how magic may not break conservation of mass and energy... and that got me thinking of a new hypothesis.

Hypothesis: conservation of mass and energy is sustained in d&d by draining energy from the catgirls to power magic and perpetual motion!

But with all the magic and physics warping stuff out there, there can't possibly be enough cat girls to power all this stuff. We would have to be wall to wall with catgirls everywhere! There's either a lot of cat girls that we can't see or touch or detect in any way (dark-cat-girls, or dark matter cat girls), or there is an Elemental plane of cat girls. Hilarity ensues when the elemental plane of cat girls invades the material plane to put an end physicists. This is also a possible reason why fantasy worlds never progress past the dark ages.

Draken
2014-10-05, 12:14 PM
If you are going to use monsters you could just cut on fiddly steps and trap air or water elementals in the turbine to make it spin. Not like the things need any kind of upkeep anyway.

Which is kind of what Eberron does, except apparently nobody there considered using the things as tireless draft beasts.

Erik Vale
2014-10-05, 08:20 PM
If you are going to use monsters you could just cut on fiddly steps and trap air or water elementals in the turbine to make it spin. Not like the things need any kind of upkeep anyway.

Which is kind of what Eberron does, except apparently nobody there considered using the things as tireless draft beasts.

Because that's what golems are for, because elementals aren't actually tireless.

Deophaun
2014-10-05, 10:58 PM
but Animated Objects (as in the monster) are constructs and aren't subject to AMFs or dispel magic.
Are you sure?

Animated objects come in all sizes, shapes, and colors. They owe their existence as creatures to spells such as animate objects or similar supernatural abilities.
Seems AMFs suppress them just fine, and some can be rendered mundane through dispel magic.

Slipperychicken
2014-10-05, 11:11 PM
Are you sure?

Seems AMFs suppress them just fine, and some can be rendered mundane through dispel magic.

Yeah, I just assumed that carried over from 3.x. My bad.

Belial_the_Leveler
2014-10-06, 02:14 PM
@bag of holding:
Even a type-1 bag of holding costs the equivalent of 50 pounds of gold. That's one million dollars. I am betting that one million dollars' worth of solar collectors produce more energy than one bag-of-holding reactor. Also, beware of liquids when loading the bag of holding. It can fit a volume of 30 cubic feet - that would be 1600 lbs of water. However, it can only carry 250 lbs of mass and thus unless you supervise its loading it could very easily rupture and destroy itself and its contents.


@brown mold:
This does not necessarily violate conservation of energy. Since it feeds on fire/heat and grows, the extra mass could come partially or wholly from the energy it absorbs.


@thoqqua:
These can only burrow (not melt) through dirt, not rock. They do continually produce heat as an average fireplace though - so a couple KW of output.







@energy production:
Generally speaking, the most efficient and cost-effective magical production of mechanical energy comes from a Reverse Gravity trap. The minimum caster level could reverse gravity in the space occupied by one half of a vertical iron disc 30 feet in radius and 10 feet thick.
The disc masses 13.000 tons and with gravity reversed in its left (or right) side, it will start turning in place by 65.000.000 N/m of torque, thus giving an energy output of 408 megawatts, or two hundred thousand Thoqqua.

Knaight
2014-10-06, 02:39 PM
@bag of holding:
Even a type-1 bag of holding costs the equivalent of 50 pounds of gold. That's one million dollars. I am betting that one million dollars' worth of solar collectors produce more energy than one bag-of-holding reactor. Also, beware of liquids when loading the bag of holding. It can fit a volume of 30 cubic feet - that would be 1600 lbs of water. However, it can only carry 250 lbs of mass and thus unless you supervise its loading it could very easily rupture and destroy itself and its contents.


Modern prices for gold really don't work all that well here. The bag of holding reactors costs as much in gp as a number of relatively small ships, which isn't consistent with a million dollar figure. One million dollars also isn't actually all that much when it comes to industrial power production - just about any power plant will vastly exceed that.

On an unrelated note, the reverse gravity trap is brilliant.

ellindsey
2014-10-06, 02:58 PM
@brown mold:
This does not necessarily violate conservation of energy. Since it feeds on fire/heat and grows, the extra mass could come partially or wholly from the energy it absorbs.


The brown mold/ammonia engine turns an output shaft forever while also gradually lowering the ambient temperature (and possibly becoming heavier at the same time as the brown mold grows). This is a clear violation of conservation of energy, regardless of what the brown mold thinks it is doing.

You can't turn heat directly into energy without violating thermodynamics. Heat is the lowest-value, highest-entropy form of energy. At best, you can build an engine that allows heat to flow from a high-temperature source into a low-temperature sink, using a steam engine or Stirling engine or some similar mechanism to derive useful mechanical energy in the process. The heat from the source isn't destroyed, just spread out into the heat sink in a less useful, more entropic form. The heat source gets colder, the heat sink gets warmer, and the amount of entropy in the universe increases.

If you want to make something colder than its environment, you have to spend energy and use a heat-pump mechanism of some type to move heat from one place to another. As in an air conditioner or refrigerator, you're actually creating heat overall as you pump heat from the inside to the outside.

Brown mold maintains a permanent temperature lower than its surroundings, creating a permanent temperature difference. By thermodynamics, it should require an expenditure of energy to do this, but the brown mold somehow works in reverse, performing an energetically expensive act yet somehow generating energy in the process. We don't really care how it does it, only that we can take advantage of this ability to generate a perpetual motion engine that doesn't require any fuel source and can do double duty keeping our Dwarven ale cold.