Exactly, but unless it does work, it fails to fulfil the ordinary defintion of ‘machine’.
no idea what its called, but besides the ‘bird’ thing…
those little black and white flags that spin around inside a ‘lightbulb’ housing… you guys know what im talkin about right?
They don’t work without an energy input (light).
They also don’t work in the way that most people seem to think they do - by ‘light pressure’.
Here’s a better explanation:
http://math.ucr.edu/home/baez/physics/General/LightMill/light-mill.html
By “Perpetual Motion Machine” I mean a device which outputs more energy than you put into it. This is the ‘classic’ purpose of such a device… there’s very little market for something which costs $5,000,000 to make and neither absorbs or produces usable energy. If you’re going to all this trouble, you are intending to be getting something for it. You invent a perpetual motion machine to power something, without having to add fuel to it. Anything else just isn’t worth the bother. I really really doubt that mankind’s quest for a pmd is so they can make more efficient birds-that-drink-water.
This being the case, a pmd is anything that, once you build it, you don’t have to fuel it up again… it just keeps producing ‘free energy’.
Like solar panels, which make free energy from sunlight. You don’t have to go to the store and buy another gallon of sunlight to pour onto the panel.
Technically not a pmd, but it serves the same purpose, see?
Think about the semi-famous Escher print, where the water flows down a channel… makes a right turn, flows down… makes another turn… makes another turn… and ends up being its own source. The water flows continuously, no beginning no end. Or, if you’re really into the whole pmd thing, any number of similar designs which also tap gravity directly. None of them work, but that’s just because it’s impossible to make a real pmd. Nonetheless, the reason isn’t that ‘there’s an outside source of energy, ie gravity’ but that whole inconvenient laws of thermodynamics thing.
Why can’t you have a pmd? Because of thermodynamics. Why does it prevent pmds? Because that’s what thermodynamics does. This is a circular argument. And it sort of misses the point I’m trying to make, which I’m afraid I still haven’t done.
And with the ‘universe’ question… again, it’s just semantics. Yes, the quark that just popped into existance must have come from somewhere, and therefore that somewhere must be in the universe, because there is no other where for it to be coming from… QED, as it were. q;}
What? Quarks don’t pop into existance out of nowhere, that’s absurd! But apparently it happens… quantum tunneling. Don’t know where they come from, but subatomic particles seem to pop in and out all the time. At least that’s how our limited perceptions see things.
The concept of Zero-Point energy seeks to capture these particles and turn them into usable energy. Basically make a box of hard vacuum, hook some wires to it, hook it to your electric car, and drive off, never needing to add fuel. Its fuel ‘magically’ appears from ‘nowhere’. Patently absurd, of course… but a real possibility, maybe.
Ahh, you say, I have you here! There’s no ‘outside’ the universe for it to come from, so it’s not really ‘free’ energy is it? And since it’s not really ‘free’ energy, it’s not a pmd. Right. But it works just like one, so who really cares.
This is why a solar panel is a pmd… if you ignore the fact the sun has to shine on it. It’s a matter of how far you’re willing to go to trace the source of the energy you are using. If I had a free car, with unlimited free gasoline, and free maintainance, I could happily live my life thinking I had a perpetual motion machine. I never have to do a thing, I get free ‘work’… yay!
Even if I could defy all laws of thermodynamics and build, say, a wheel that just spins forever with absolutely zero energy loss… it’s not really zero is it? I mean, the wheel is made of something, and it took effort to find that stuff and shape it into a wheel. So before it’s even turned on at all, it’s less than 100% efficient… the cost to create the item itself. In order to take THAT into consideration, a pmd would need to be MORE THAN 100% efficient to be 100% efficient! Oh boy! More paradoxes!!
Get out there and give me 110%!!!
That’s impossible… by definition 100% is the maximum that we could give!
In THIS house, we obey the LAWS of Thermodynamics!!!
Whoah… Simpsons is really kinda deep isn’t it?
Can ya tell I’ve been up all night?
So to sum it all up… a PMD is something that gives you usable energy, without requiring you to fuel it. A hydroelectric dam, in one sense, fulfills this requirement… if you ignore the rest of the universe, ALL of which is required for it to work, NONE of which you have to worry about.
You can make your own perpetual motion machine as follows…
- get a cat
- spread some butter and jam on the cat’s back
- drop the cat from a 10ft
… hey presto! the cat will spin for infinity!
There are two laws of physics at work here: a cat, when dropped from a relatively low height will always land on its feet; and when you drop a slice of bread it always lands buttered side down.
So when you pit the forces against each other, they cancel each other out and spin forever.
Nice long, very interesting, well thought-out, but totally incorrect post. A PMD is defined as a device from which you can extract more energy than is put in. Period. By this, we mean the total energy put into and removed from the system, including losses, not just the effort you put into keeping it running and the usable energy extracted. There are no devices, mechanisms, systems or sound theoretical concepts which can do this. I appreciate the point you are trying to make, but my point is that in science there are very specific definitions of things like PMDs we have to consider.
I have got a strange intuition that even if you did manage to extract zero point energy from the vacuum-
you would actually be extracting it from the universe as a whole, by slowing down the acceleration of universal expansion;
a bit like tapping dark energy.
But this wouldn’t be a PMD either, although it might do plenty of useful things.
SF worldbuilding at
http://www.orionsarm.com/main.html
Ok, QED, yes, you’re absolutely right. The SCIENTIFIC definition of PMD is as you say. The PRACTICAL definition is something else.
Normal item: 1=1
pmd: 1=1.1
Obviously a pmd is impossible. MY point is that we can make things which are effectively free-energy machines.
NOT a true pmd, if you get all scientific about it. But for all intents and purposes, yes, it is.
I say you can get energy for nothing. You say, no, you have to have input. I say that input is free. You say, no, that’s not good enough. Even free energy comes from somewhere, so it’s not a pmd. I say ok let’s use the energy that comes, literally, from nowhere (zero-point). You say no, that’s STILL not good enough, because by definition universe is everything, even stuff that’s something else.
Fine. You win. You go on burning gasoline, the rest of us shall conquer the universe with its own energy. q;}
Well, since the term “perpetual motion machine” is already taken and rigidly defined, why don’t you use a different, less confusing term? Like “free input energy system” or “something-for-nothing energy” or…whatever tickles your fancy. I know you can use the term “perpetual motion machine” to refer to donuts, or platapi, or whatever (“When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean – neither more nor less.”), but you can hardly blame others for being confused by your alteration of its generally accepted meaning.
And, accepting that you’ve redefined “perpetual motion,” what exactly is your question. Yeah, hydroelectric dams are sources of “free” energy as long as the sun lasts. So what? Saying you’ve discovered perpetual motion by redefining the term is like the administration saying they’ve ended poverty by lowering the poverty line.
Leaving the thermodynamic impossibility aside entirely, I have to wonder what you’re expecting a siphon to do for you. Siphons move fluids downhill, after all, something that can be perfectly naturally achieved without the siphon. I can’t picture what you’re picturing.
Is it possible to achieve perpetual motion by taking advantage of time dilation effects around a black hole?
Phnord Prephect, the problem with using “zero-point” energy is that you are really just utilizing a resource of the universe, the same way we burn gasoline. A perpetual motion machine must be able to create energy itself, not take advantage of a naturally occurring source of energy in the environment. The purpose of thermodynamics is to describe how things actually are; it is not designed to prevent PMDs, it merely stating that they are in actuality impossible.
Quoth The Controvert:
There are three known ways to use a black hole as an energy source. The simplest to implement is the Penrose process, which extracts energy from a rotating black hole. However, the only energy available here is the rotational energy of the hole, not the so-called “irreducable mass”. Once you’ve stopped the black hole spinning, there’s no more energy available, and anything you could do to start the hole spinning again will cost you more energy than it’s worth.
The second method is the quasar process: You drop matter into the hole, and turn the potential energy into some other, useable form. You can use any black hole at all for this, and drop in any sort of matter at all. If done perfectly efficiently, this can get you energy equal to half the conversion energy of the mass you drop in (the rest gets eaten by the hole, increasing its mass). Perfect efficiency probably isn’t practical, but even if you only get a small fraction, that’s still a lot of energy.
The third method is Hawking radiation. For a black hole of normal size, Hawking radiation is far too slow to be useful. But if you somehow got a small enough black hole, you could get useful energy out of it. Since you don’t want your power supply to dissappear on you, you would want to simultaneously feed the hole, at the same rate that it’s radiating. This will end up getting you up to the full conversion energy of the matter you feed in. This might be a rather difficult proposition, though, since there’s a strong positive feedback: The smaller the hole, the faster it radiates away, so if you ever fall behind on your feeding, your next feeding will also be too small, and it’ll run out of control, while if you feed it too much, it’ll become too cold, and take a very long time to become useful again.
Of course, while all three of these would produce extremely inexpensive energy, none of them is quite free. In the first case, you’re limited by the energy initially in the black hole, and in the second and third, you’re limited by how much you can throw in. Either way, you’ll eventuall run out.