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Perpetual Motion

HutchTheCrutch

Student
HutchTheCrutch
Joined
Nov 19, 2004
Messages
33
I was wondering just how one would go about testing for a claim perporting to have invented a perpetual motion machine.

Any ideas??

HTC.
 
Well if they can pass an examination by an expert who can confirm that it is not using a replenishable fuel supply, or a stored fuel supply, and it appeared to work, then I suspect the claimant would win the money.

I don't know if there would be much more to it.
 
I think it should be reasonably simple, even without examining it (the inventor might object to having his Nobel prize winner machine examined). Weigh it. Calculate the maximum amount of energy any known energy storage device (will probably be some kind of fuel cell) can hold. Connect it to a generator and measure the energy output. When the machine has put out considerably more energy than could possibly be stored in it (e.g. five times as much), weigh it again. If it weighs the same, it is indeed a perpetual motion engine. The reweighing is, of course, to rule out any kind of fuel consuming machine that might have a very high energy density. All the time, it must, of course, be ensured that there is no energy input.

Hans
 
A box with a infrared-sensitive 'solar cell'-type device on the inside would pass such a test. It would give out a small amount of electricity until you cooled the whole setup down to some seriously low temperatures (well, that would be the "ensuring no energy input" part).

All kinds of electromagnetic radiation could be picked up and converted to electricity, so you would have to block the local radio channels and the microwave generator hidden in the next room.

And you would have to be very quiet. A microphone is a device that converts sound waves to electricity. etc, etc... :)

So you would need a well shielded room and a minimum requirement for the power output. Sneaking in a microwatt or two isn't that difficult, but any useful perpetual motion machine should at least give out a few watts. And any serious perpetual motion scam would claim much more than that. Since the testing procedure has to be mutually agreed upon, such a minimum power limit should be included.

Ririon
 
Another way to the pass the "weight loss" test would be to extract water vapor from the air to make up the difference.

IXP
 
Nice answers guys, however how could one define the word 'perpetual' ? If a machine is truly perpetual it should go on literally forever and I can't see how you would be able to verify that?
 
Hutch, it just means more energy is output than input.
 
HutchTheCrutch said:
If a machine is truly perpetual it should go on literally forever and I can't see how you would be able to verify that?
Click to expand...
I's one of those things you have to accept; like ' infinity '..

If you can demonstrate a lossless mechanism, it is safe to assume it will remain so.
 
This may be a stupid question, but it's something I've always kinda wondered about perpetual motion machines. Even if you did somehow manage to design and build one (and we all know how likely that is), how would you deal with the problem of wear and tear?

After all, it has all the time in the universe to malfunction due to part wear. Seems a pretty safe bet that it would, eventually. At which point, could it still be considered a perpetual motion machine?
 
When speaking about "perpetual motion", the efficiency of the machine is being measured, not necessarily the duration of time it could operate. The fundamental breakthrough such a machine would signify is efficiency in converting energy beyond 100%, which would be a huge breakthrough indeed. Heck, we get whooping and hollering when we break 50%.

Thus, the test of the machine would be to see whether or not it could put out more energy than it is taking in, as pointed out before, it's imperative that the energy imput be carefully accounted for lest the illusion of perpetual motion be created. If such a machine could exist, it would be violating natural law as we know it, and would be capable of indefinate operation in principle, the wear and tear would be largely irrelevant to the spirit of the thing. We don't say that zepplins aren't lighter than air because they have to land occasionally.
 
"Perpetual motion" is, of course, a shorthand way of referring to a class of things that operate by producing more energy than they expend (in a closed system), usually expressed in the form of something moving. There is no expectation in that name that they operate forever ... it is simply a convenient moniker to represent "they *would* operate forever in terms of energy in / energy out."

- Timothy
 
Timothy said:
"Perpetual motion" is, of course, a shorthand way of referring to a class of things that operate by producing more energy than they expend (in a closed system), usually expressed in the form of something moving. There is no expectation in that name that they operate forever ... it is simply a convenient moniker to represent "they *would* operate forever in terms of energy in / energy out."

- Timothy
Click to expand...

A perpetual motion machine only has to produce enough energy to meet the needs of its own function plus any losses. In other words, it's a zero-sum equation. Any machine that produces more energy than it requires is an "over-unity" machine.

However, I do agree that there is no requirement for a PMM or OUM to run forever without servicing or maintenance.

Regards;
Beanbag
 
In principal I think a PMM usually has to be a OUM. The whole thing can't have no energy loss anywhere, so it has to break entropy and conservation somewhere.
 
dinosaur_knight said:
This may be a stupid question, but it's something I've always kinda wondered about perpetual motion machines. Even if you did somehow manage to design and build one (and we all know how likely that is), how would you deal with the problem of wear and tear?

After all, it has all the time in the universe to malfunction due to part wear. Seems a pretty safe bet that it would, eventually. At which point, could it still be considered a perpetual motion machine?
Click to expand...

The trick is, you have to design a machine that will not suffer wear and tear. That is, that incurs no friction. The only thing I can think of would be some sort of mag-lev operating in a vacuum. Of course, this assumes that the magnativity(is that a word?) will never disapate. My own sci-fi device would be a mag-lev subway system, say under New York, with evacuated tubes, and stations that could also be evacuated after the train has loaded. Of course, the train's infrastructure would consume a hell of a lot of replacable energy in creating and maintaining the vaccuum and in propelling the cars, but the train, itself, would incur no friction.

But then, that really doesn't fit the definition, does it?
 
neutrino_cannon said:
In principal I think a PMM usually has to be a OUM. The whole thing can't have no energy loss anywhere, so it has to break entropy and conservation somewhere.
Click to expand...

Depends on how you want to define it. A PMM only needs to produce enough energy to equal its losses. A PMM where everything balances out (including entropy losses) would run just fine as long as there was nothing else to sap energy from the system.

If you want to generate excess energy to run something else, then you need a OUM that is producing more energy than the machine consumes.

Minor point, to be sure. A PMM just runs itself. An OUM runs itself plus something else.

Regards;
Beanbag
 
Beanbag said:
However, I do agree that there is no requirement for a PMM or OUM to run forever without servicing or maintenance.
Click to expand...

Maybe it's a limitation of the language, but "perpetual" means "perpetual," not "extended" or "long duration."

If a part wears out, this will be due to friction, which is the conversion of potential energy to kinetic in the form of heat, and is lost to the machine. If the part has to be replaced, then you are also replacing that part's store of potential energy. IOW, you are, in principle, refueling the machine.

Therefore, any machine that requires servicing requires energy replacement from external sources to continue operating, and cannot be classed as "perpetual."
 
The whole question is very difficult, it is almost as if it is phycically impossible to build one.
 
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