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Perpetual motion machine examination rules, please.

Perpetual motion is not the challenge - it is a perpetual motion machine which is the challenge.
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My understanding of the challenge is based on the Randi quote I posted earlier in this thread. My understanding is that gravity is a force and is conservative and you can't cause a dropped weight to regain it's former height. Or in other words every last single solitary force acting on a falling mass is conserved and you can't end up with enough force after a weight has fallen to cause that weight to raise itself in its orbit and begin it all over again. A machine would do that and also do some work yet I don't think that a machine is the challenge. Does anyone have any thoughts on this?

A. Gene Young
 
Of course the standard disclaimer applies here that my opinions don't in anyway represent official JREF views.

Having said that, I think it is very likely that a claim of a functional PMM similar to the one you seem to be describing would be accepted by the JREF organization for testing. Of course, some method would be required to prove that the device was what you claimed it to be and that it didn't contain hidden energy sources.

I have to say, that it just baffles me that you could imagine that you will succeed. Do you understand that any mechanical device that has moving parts will lose energy to heat because of friction? Do you believe you have a method of building a mechanical device that will produce enough excess energy to replace the energy lost to friction as the device rotates? Do you have some thoughts about where this energy would come from?
 
AgingYoug: The machine is the challenge - simply to set something in motion in perpetuity is within physics - at least in principle. Making a machine utilising this principle is not. (Check deefinition of "machine".)

David: The machine submitted for the test dosn't need to overcome friction to demonstrate that a PMM is possible. For instance, in the case of a moving-weights machine, one could fix the weights in place and drive the wheel with applied torque from a weight dropped a known height (say). Time the fall, then repeat with the weights freed. If the applied torque is in the direction of pmm spin, then the weight will fall more slowly; if the applied torque is in the direction of pmm spin, then the weight will fall faster. (See the museum prev cited for examples.)

More careful experiments could be derived for different configurations. It would, of course, be helpful to have some advance idea of the size of the effect looked for so that the experiment can be constructed to appropriate tolerances. If the effect is small, you wouldn't want to lose it in the uncertainties.

Just demonstrating that a device of proposed design can do it in principle is enough to break known physical laws.
 
AgingYoung said:
...the laws of physics aren't immutable; they're our best understanding of the world we live in.​
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Quite true, but the laws have been refined and proven accurate for a very long time. This is particularly true of the laws governing the behavior of purely mechanical or electromechanical devices, because the operation of these devices is more readily observed. While there may be unknown or poorly understood happenings at the atomic or subatomic level, the effect of these has never been observed to violate the existing laws.
 
AgingYoung said:
It's possible we don't know everything. I know it's remote yet still it's possible.
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Yes, it's certainly possible that we don't know everything. But if we're right about Newton's law of gravitation and his laws of motion, then gravity is a conservative field and therefore a gravity-powered perpetual-motion machine is impossible.

From what you've written here, it doesn't sound like you disagree with our current understanding of gravity and motion---for example, that the force of gravity on an object is proportional to the mass of the object and is directed towards the center of the Earth, or that the mass of an object remains constant as it moves around one of your machines, or that the acceleration of an object is proportional to the net force on it and inversely proportional to its mass, etc. Rather, it sounds like you think that even though all those individual facts are correct, a gravity-powered perpetual-motion machine might nevertheless be possible. That's simply false, and its falsity can be proven mathematically.
 
AgingYoung said:
My understanding of the challenge is based on the Randi quote I posted earlier in this thread. My understanding is that gravity is a force and is conservative and you can't cause a dropped weight to regain it's former height. Or in other words every last single solitary force acting on a falling mass is conserved and you can't end up with enough force after a weight has fallen to cause that weight to raise itself in its orbit and begin it all over again. A machine would do that and also do some work yet I don't think that a machine is the challenge. Does anyone have any thoughts on this?

A. Gene Young
Click to expand...

there is your problem. Gravity is not a force. It is an acceleration. So your starting point will likely lead you to a false conclusion. Remember that assume can be turned into ASS-U-ME
 
rwguinn said:
Gravity is not a force. It is an acceleration.
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Huh? What does that mean?

If I stand motionless on a bathroom scale, nothing is accelerating. But the Earth is still exerting a downward force on me, and the scale's readout shows me how strong that force is.
 
69dodge said:
Huh? What does that mean?

If I stand motionless on a bathroom scale, nothing is accelerating. But the Earth is still exerting a downward force on me, and the scale's readout shows me how strong that force is.
Click to expand...
nope--the gravitational field is exerting an acceleration on your mass. The ground (or scale) is resisting that acceleration of your mass with a force exactly equal to your mass times the acceleration. That is what the scale reads.
 
rwguinn said:
nope--the gravitational field is exerting an acceleration on your mass. The ground (or scale) is resisting that acceleration of your mass with a force exactly equal to your mass times the acceleration. That is what the scale reads.
Click to expand...

The gravitational field is exerting a *force* on your mass - inducing acceleration. How can acceleration be "exerted"?

(edited for spelling)
 
Last edited:
rwguinn said:
semantics. The force is a result of the acceleration, not the cause of it.
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Quite sorry to report, but acceleration is a result of force, not the other way around. Gravity is a force. I could post numerous links for a quick and dirty dictionary war, but I think it will suffice for now to allow you to seek a source defending your own point first. You may find it illuminating.
 
I have to agree that gravity is an acceleration. To find the weight of an object, which is a force, you multiply its mass by the acceleration due to gravity in the equation F=ma, or in this case F=mg, where mg is the force, not g alone.
 
petre said:
Quite sorry to report, but acceleration is a result of force, not the other way around. Gravity is a force. I could post numerous links for a quick and dirty dictionary war, but I think it will suffice for now to allow you to seek a source defending your own point first. You may find it illuminating.
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and a dictionary is a physics book in what language?
Gravity (on earth)=9.81 m/sec^2=32.2 ft/sec^2=386.1 in/sec^2. Those values, folks, are accelerations. Now you can get into semantics all you want, but the force is a result of an acceleration acting on a mass. The entire purpose of physics and such is to model an accurate approximation of reality. Treat gravity as an acceleration and you do that. Treat it as a force, and you can go astray easily.
Weight is a force. think of it this way: A force can be measured. Put a scale on the side of a 100 lb box, and push it with a 10 lb force. Then put the same scale on a 1 lb box and (try to) push it with a 10 lb force. Big difference in reactions, huh?
If gravity were a force, the value of weight would be constant, and we would all weigh the same.
 
rwguinn said:
and a dictionary is a physics book in what language?
Gravity (on earth)=9.81 m/sec^2=32.2 ft/sec^2=386.1 in/sec^2. Those values, folks, are accelerations. Now you can get into semantics all you want, but the force is a result of an acceleration acting on a mass. The entire purpose of physics and such is to model an accurate approximation of reality. Treat gravity as an acceleration and you do that. Treat it as a force, and you can go astray easily.
Weight is a force. think of it this way: A force can be measured. Put a scale on the side of a 100 lb box, and push it with a 10 lb force. Then put the same scale on a 1 lb box and (try to) push it with a 10 lb force. Big difference in reactions, huh?
If gravity were a force, the value of weight would be constant, and we would all weigh the same.
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I understand that those values are accelerations.
However, according to above, if there is no mass, the acceleration doesn't "happen" (exist?). And therefore no force is evident.
On the contrary, the force is always "there" (whatever system we are looking at) and perception becomes evident when mass is introduced.
 
Great - now I'm thinking about the chicken and the egg....
The tree falling in the forest...

(edit - added tree)
 
rwguinn,
You seem to making something of a semantic point with regard to your notions about force and gravity.

I assume that you realize that gravity is listed as one of the four fundamental forces by every physics textbook that deals with force.

Further, I assume you realize that the formula for force between two objects based on their gravitational attraction yields a value with force units.

Further, I assume you realize that without your semantic point it is perfectly possible to make predictions about the motion of matter in a gravitational field.

So given all that I don't really understand why you see that there is value in your assertion. It is absolutely not the view that this engineer was taught in his physics classes nor is it a view I have seen expressed any place else.
 
Grounded said:
Great - now I'm thinking about the chicken and the egg....
The tree falling in the forest...

(edit - added tree)
Click to expand...
pretty much the case:D
In engineering, we refer to "Force due to gravity" and "Gravitational acceleration".
Again, it all boils down to semantics. Mathematically, gravity is always applied as an acceleration. This is the convention used, and it makes for a very good simulation of reality.
The fact is that gravitational acceleration (semantics, again--it can be confusing) is a constant on any body around. (or rather, an approximate constant--there are local variations for any body, depending on distance from the (groan) center of mass.)
on Earth, it is 9.81 m/sec^. on the earth's moon, it is about 1.633 m/sec^2, and so on.
By using an acceleration, we have a constant we can use to determine the force acting on any other mass residing on that body, instead of some variable force from which the mass must be extracted. This also has the beauty and simplicity of rendering the mass of a given body a constant, regardless of where it is. This is very handy when doing analysis for an object built on earth and sent to, say, Mars.
Does that help?
 
davefoc said:
rwguinn,
You seem to making something of a semantic point with regard to your notions about force and gravity.

I assume that you realize that gravity is listed as one of the four fundamental forces by every physics textbook that deals with force.

Further, I assume you realize that the formula for force between two objects based on their gravitational attraction yields a value with force units.

Further, I assume you realize that without your semantic point it is perfectly possible to make predictions about the motion of matter in a gravitational field.

So given all that I don't really understand why you see that there is value in your assertion. It is absolutely not the view that this engineer was taught in his physics classes nor is it a view I have seen expressed any place else.
Click to expand...
See my previous post...
 
Simon Bridge said:
AgingYoug:
David: The machine submitted for the test dosn't need to overcome friction to demonstrate that a PMM is possible. For instance, in the case of a moving-weights machine, one could fix the weights in place and drive the wheel with applied torque from a weight dropped a known height (say). Time the fall, then repeat with the weights freed. If the applied torque is in the direction of pmm spin, then the weight will fall more slowly; if the applied torque is in the direction of pmm spin, then the weight will fall faster. (See the museum prev cited for examples.)

More careful experiments could be derived for different configurations. It would, of course, be helpful to have some advance idea of the size of the effect looked for so that the experiment can be constructed to appropriate tolerances. If the effect is small, you wouldn't want to lose it in the uncertainties.

Just demonstrating that a device of proposed design can do it in principle is enough to break known physical laws.
Click to expand...

I am not sure I understand your point here Simon Bridge.

If the claim is for the demonstration of a physical phenomena that could theorectically be used to build a PMM then perhaps there is something to what you are saying.

In this case the claim would be for a PMM. There seems to be a consensus in this thread that a device that was based on the complete elimination of friction might not be called a PMM at all. Earlier I gave as an example of a device that has nearly accomplished perpetual motion, the gyroscopes in the gravity probe b satellites. The gyroscopes contain nearly perfectly spherical quartz balls that are suspended with electrical forces and rotate in a nearly perfect vacuum. I believe the gyroscope balls can spin for years without the addtion of any energy. But I don't think anybody is calling this a PMM.

It does not sound like AgingYoung proposes to completely eliminate friction from his device. So if the device is to keep moving the device must contain a method for generating enough of an energy surplus at a minimum to replace the energy lost due to friction. And my question still stands: What does AgingYoung think the source of that energy would be in his device?
 
davefoc said:
rwguinn,
You seem to making something of a semantic point with regard to your notions about force and gravity.

I assume that you realize that gravity is listed as one of the four fundamental forces by every physics textbook that deals with force.

Further, I assume you realize that the formula for force between two objects based on their gravitational attraction yields a value with force units.

Further, I assume you realize that without your semantic point it is perfectly possible to make predictions about the motion of matter in a gravitational field.

So given all that I don't really understand why you see that there is value in your assertion. It is absolutely not the view that this engineer was taught in his physics classes nor is it a view I have seen expressed any place else.
Click to expand...
Actually, it is all a matter of chosing a convention that makes sense to you. I know a large number of engineers who do analysis based on weight, and simply apply a unit acceleration to the system, and get perfectly decent results. They seldom do anything that leaves this planet, however. Nor do they do much frequency domain analysis, and often get confused when they do..
Yes, I am aware of the points you make. the attraction between 2 bodies does come out as a force. You can apply the equation to things on earth, or the moon, or Mars, or wherever. Why make life complicated, though?
I don't do orbital mechanics for a living, however, and either method may be used to determine dynamic situations in a gravitational field--whatever that may be.
 
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