I was pondering perpetual motion one day, and yes I know it technically defies one or two laws of thermodynamics, but I wondered…could hydroelectric power be considered “in spirit” perpetual motion?
This stemmed from my thoughts about a siphon-driven, gravity based, method of generating power. When I extrapolated these ideas, I realised that dams pretty much work the same way. They do however, defy the definition of perpetual motion because they have an unlimited source of energy, rain.
So, my question is, is a “hypothetical continuous operation of an isolated mechanical device or other closed system without a sustaining energy source” a realizable goal, or are available natural circumstances a negation of this definition? Don’t dams provide power for as long as condensation/rain continues, or untill their parts wear out? Is this more of a semantic question because our physics laws prevent it?
I suppose it could be a pipe dream that is unnatainable by definition, but I’d like to think that such a thing does exist. Maybe we just can’t harness it because we haven’t figured out that level of physics yet.
I’m sure that I’m missing some obvious mechanical and theoretical issues here, but I’d appreciate some corrective input.
Rain is not the source of the energy, of course, it is the sun.
And the sun is powered by fusion, which is only made possible by the existence of the universe -
Iyou are looking for a free-lunch, something-for-nothing device-
the universe as a whole has apparently appeared from nothing, and performs useful work…
if you can make another one of those, you have cracked it.
Most energy we use comes from the sun, if you think about it. Fossil fuels come from plants and plankton which used sunlight to grow. Wind and rain are powered by the sun. The only exceptions are geothermal and nuclear power.
There is no such thing as a ‘closed system’ anywhere. Even the entire universe has ‘other stuff’ outside of it… ie ‘higher’ dimensions, parallel realities, etc etc.
Coal is a perpetual motion device, if you ignore the fact you have to dig it up and burn it, and that it is dead plants, which got their energy from the sun.
Natural gas is a pmd, if you ignore the fact that living beings produce it, which get their energy from other living beings, and ultimately from the sun.
Hydroelectric is a pmd, if you ignore the fact that you get the water from rain, which got there with energy from the sun, and the gravity of the earth which pulls the river water thru the turbines.
Solar is a pmd, if you ignore the fact that it uses the energy of the sun.
Nuclear power is a pmd, if you ignore the fact that it takes a supernova to cram enough hydrogen atoms together to make a uranium atom.
All of these use the same concept: ENTROPY. The natural order of the universe breaks things down, releasing energy in the form of heat.
No. by definition the universe is everything there is. There is nothing “outside” of it. The so-called higher dimensions required by superstring theory are firmly enclosed within the universe itself, and integral to the very fabric of spacetime. So-called parallel realities may or may not exist, but if they do, they, too, are part of the universe.
Please explain the rest of your post. How are any of those things even remotely to be considered perpetual motion devices?
Ok, here is the long and short of it. In order for something to be perpetually in motion it either A: Must never have energy removed from it (friction, driving a motor, etc.), or B: Be continually supplied with energy from an outside force. Typically when speaking of a “perpetual motion machine” people are thinking of a machine that experiences friction, but never slows down despite not receiving any energy input. This violates the law of conservation of energy; basically you cannot remove more energy from a closed system than was added.
There is only one way to make a perpetual motion machine, and that is to remove all energy loss from whatever object is in motion. As this requires defeating friction (which has not been done yet), it is safe to assume that everyone claiming to have created a perpetual motion machine is lying.
In conclusion, hydroelectric power is not “in the spirit” of perpetual motion as it is an extension of the power input of the Sun. You could call it “a machine that is perpetually in motion”, but that is not quite a “perpetual motion machine”.
Seeing that there is no known “perpetual motion” machine, what is the closest man-made type mechanism that recaptures it’s spent energy most efficiently?
Same problem. In order to extract any energy, you have to toss in mass and collect what energy is radiated just before the event horizon. I don’t know what the efficiency might be, but you’ll never get mc[sup]2[/sup] out of it.
I would imagine some sort of magnetically driven oscillator operating in a vacuum (or as close to a vacuum as we can get) would be the closest thing to a PMD that man could achieve right now. That would effectively negate friction from the air and from mechanical contact. My EM background is sorta rusty, so I’m not sure what other forms of energy would be sapped from the system. Gravity would be a bit of a hassle, but I’m sure the magnets could be intelligently designed and arranged such that they took gravity into account.
Jeff
Not to be, ahem, dense, but why would I care if I got mc^2 out of it? As long as stuff keeps falling in, I got perpetual motion. All you need is a way to capture the change in potential energy, right?
Well, yes, but my point was really that eventually, you’ll run out of mass to feed it. It’s no different than a coal-fired power plant that will generate power as long as you can stuff coal into it.