perpetual motion machines

[Shalmanese]

Technically, theres no reason why a perpetual motion machine isn't possiblre except that they violate the laws of physics as they NOW stand. If we were to suddenly find a loophole, then we could very well build a PM machine. The ramifications of this would be quite interesting. Firstly, the most important thing would be to check if we could build a reverse PM machine, that is, one that sucks energy out of the universe. If that were not possible, then we would be limited by how much heat we could radiate off the earth. If we could make a reverse PM, then we could do all sorts of neat stuff. We could litereally build things atom by atom out of energy. We wouldnt need to worry about ever running out of anything since we would just get more. We could make anti-matter by the ton and do all sorts of useful stuff. We could put down suns and planets where we wanted and have a custom-built dyson-sphere ready to go.

 

[f95toli]

I am not sure we could do any of those things because suddenly everything we thought knew about physics would be wrong.
Conservation of energy is the most fundamental thing there is in science, if that is wrong than everything else is also wrong, we would need to start from scratch again.

 

[TDSLB]

Hey I didn't learn it the first time so I'm up for somethin' new.

what do you mean by making antimatter by the ton? isn't one of the bassis of anti-matter the fact it has no weight? If you would please elaborate on that I would appriciate it.

 

[imgod2u]

Well, science is the search for truth as we observe it. If we observe something that contradicts everything we thought before, then all that came before has to go. There's no debating it. Now, as I mentioned above, quantum effects do make perpetual motion devices feasible on a very small scale. The problem is finding a way to harness that.
As for the ramifications of perpetual motion machines. It all depends on how that is achieved. As I mentioned, at the quantum level, conservation of energy does not neccessarily hold. This does not negate the fact that at the macro-level, the sum averages of quantum effects does not invalidate conservation of energy so all that we thought were true before still holds. It's just that we have to make an amendment to the rule: only at the macro-level.
Implementations of true perpetual motion machines would mean we would have devices that would never require new sources of power. They could potentially take a source of power, and use it indefinitely. Batteries would last forever, cars would keep on running, TV's won't need to be plugged in. Which brings me to my next point. This certainly would bring the battery and electricity industry to a screaming halt. Perhaps this is why perpetual motion devices have not been invented. The electric and battery companies are paying big bucks to keep it down so they'll stay in business!

 

[Shalmanese]

Quatumly, you can "borrow" energy from surrounding space but there is well defined limits as to how much you can borrow and for how long. Theres no way to make a perpetual motion machine out of it. As for antimatter, its exactly like normal matter except the charges are switched around. So anti-matter does have mass. It would be the smae difficulty making antimatter as normal matter.

 

[imgod2u]

Not according to what I've read. No noticable loss in energy was "borrowed" from anything. As for limitations, quantum effects are, as I stated, very slight, however, the energy can be consistently harnessed to something noticable from the macro level (such as the Casimir effect). This indicates that it's not "borrowing" energy. It is, indeed, creating it, and then destroying it. If you harness the energy before it is destroyed, you pretty much have new energy. Read up on "zero level energy" (I think that's what it's called) and the Casimir effect. Also read up on Virtual Particles and the Uncertainty Principle.

 

[f95toli]

You do "borrow" energy in a way. The point is that since the uncertainty principle tells us that energy can not be definied to within an arbitrary accuracy there are always zero-point flucutations even i vacuum, but the average enery is still zero. A good example of how this works is Hawking radiation, a pair of virtual particles are created (in vacuum) close to the event horizon of a black hole ; one particle can become real only if the other is sucked into the black hole, some energy is effectivly "stolen" from the black hole. The total energy is conserved even though a new particle has been created.

 

[Shalmanese]

Casmir effect does not violate conservation of energy.

 

[jhu]

But in that case wouldn't the possibility of one be in space without gravity. If you just started spinning a disc wouldn't it keep spinning for lack of work done?


no because the disc would be radiating energy thus slowing it down. the same thing happens with collapsed stars: they spin really fast all the while slowing down due to radiation

 

[imgod2u]

Originally posted by: f95toli
You do "borrow" energy in a way. The point is that since the uncertainty principle tells us that energy can not be definied to within an arbitrary accuracy there are always zero-point flucutations even i vacuum, but the <EM>average</EM> enery is still zero. A good example of how this works is Hawking radiation, a pair of virtual particles are created (in vacuum) close to the event horizon of a black hole ; one particle can become real <EM>only</EM> if the other is sucked into the black hole, some energy is effectivly "stolen" from the black hole. The total energy is conserved even though a new particle has been created.

"Borrow" would indicate that something, somewhere else, was loosing the energy gained from the quantum flux. This has not been observed in lab tests. As for "averaging out". That does not mean energy is conserved. If I walked around in a circle and ended up in the same place, would you say I didn't move? I did move, I merely ended up in the end where I started. The same is of quantum flux. Energy is created, and then destroyed. It is not conserved. It merely averages out to be the same.

Casmir effect does not violate conservation of energy.

What would you call two metal plates that move towards eachother without any energy being added to the isolated environment or system then?

 

[Fencer128]

Originally posted by: imgod2u

Originally posted by: f95toli
You do "borrow" energy in a way. The point is that since the uncertainty principle tells us that energy can not be definied to within an arbitrary accuracy there are always zero-point flucutations even i vacuum, but the <EM>average</EM> enery is still zero. A good example of how this works is Hawking radiation, a pair of virtual particles are created (in vacuum) close to the event horizon of a black hole ; one particle can become real <EM>only</EM> if the other is sucked into the black hole, some energy is effectivly "stolen" from the black hole. The total energy is conserved even though a new particle has been created.

"Borrow" would indicate that something, somewhere else, was loosing the energy gained from the quantum flux. This has not been observed in lab tests. As for "averaging out". That does not mean energy is conserved. If I walked around in a circle and ended up in the same place, would you say I didn't move? I did move, I merely ended up in the end where I started. The same is of quantum flux. Energy is created, and then destroyed. It is not conserved. It merely averages out to be the same.

Casmir effect does not violate conservation of energy.

What would you call two metal plates that move towards eachother without any energy being added to the isolated environment or system then?

Here is a quick explanation of the Casimir effect that I googled.

The energy comes from the vacuum. Conservation of energy is not violated.

...An elegant analysis by Milonni, et al., at Los Alamos National Laboratory shows that the Casimir force is due to radiation pressure from the background electromagnetic zero-point energy which has become unbalanced due to the presence of the plates, and which results in the plates being pushed together...[10]

The article also discusses the use of the effect with "perpetual motion" machines - and quite rightly concludes that although energy can be extracted from the vacuum as a force, you'd need a "free" way of moving the plates back to their starting positions --> no good for perpetual motion.

Cheers,

Andy

 

[BruceLee]

Originally posted by: f95toli
I am not sure we could do any of those things because suddenly everything we thought knew about physics would be wrong.
Conservation of energy is the most fundamental thing there is in science, if that is wrong than everything else is also wrong, we would need to start from scratch again.

If all "scientists" worked in this manner, there would be no scientific progression at all. Think back to how people felt before Newton started his deal. Did they think they were wrong??? They couldn't fathom the fact that a "fundamental thing in science" (whether it be about motion or whatever) was wrong. Relative to our time frame, you could say that conservation of energy is the most fundamental thing in science. However, times change, and as one biological species (humans) get better and better at observing the physical facts of nature theories and so called "laws" change. Everything people have known about science has suddenly gone wrong at some point (maybe not entirely wrong, but at least unable to answer a certain set of questions), that is how science works. If you ever explore (or are exploring currently) any scientific studies, it would not be wise to view things from this perspective. Please understand I am not trying to criticize you, just pointing out that this way of thinking just is not scientific.

 

[f95toli]

Well I hope my way of thinking is at least somewhat scientific since I am a scientist
I understand what you mean but I do not agree. "Science" as I define it has been around for about 500 years (some fields, medicin has been scientifc for about 200 years and social sciences ever less) and during that time a number of laws and theories have been developed. Very few well established theories and laws have turned out to be wrong and all the fundamental laws still holds. The way we interpret the laws have in some cases changed dramatically but the mathematical formulations still holds, some "laws" like Newtons have turned out not to be valid in all situations but that does not mean that they are wrong.

Conservation of energy is probably the most fundamental law there is in physics, removing that would mean that EVERYTHING in physics is wrong since all laws and theories use the conservation of energy in some form. We would have to start from scratch and try to come up with for example a replacement for Maxwells theory of electromagnetics. We simply would not know where to start.

 

[sgtroyer]

F95toli, I guess I would have to disagree. Conservation of energy works very well for us now, and all evidence I know of supports it, but that doesn't mean it has to be right. We may find some evidence in the future that disagrees. Newton's Laws and Maxwell's Equations seem very right, and almost all evidence backs them up, but they're wrong. The fact that they're not valid in all situations means that they're wrong. They're still useful approximations if you're not going very fast or not looking at something very small, but they've been superceded by relativity and quantum mechanics. A physical law can only remain right when it explains all of the evidence.

If we find evidence to contradict conservation of energy, or the 2nd law of thermodynamics, or something else fundamental, that won't shake the foundations of physics as much as you claim. Conservation of energy will still be a useful approximation for most situations, and we'll still use it for most situations.

Every physical law is waiting for the day that it will be superceded by something more accurate, more comprehensive (and more complicated). I personally don't ever expect the day that perpetual motion will be practical, as in able to be built, and I'm quite certain it's ruled out by today's physics, but I can't rule out the fact that physics could change enough that it could become theoretically possible.

 

[Shalmanese]

To be practical, even IF conservation of energy were found to be wrong, the conditions under which it would happen and the amount of energy that could be extracted would likely be small enough that it wouldn't be much of a deal in the practical sense. The very fact that we've looked at it in all the most obvious places already suggests that you would probably need some fairly esoteric conditions.

 

[Smilin]

Originally posted by: blahblah99
One way to do it would be to suspend a disc in a magnetic field in a perfect vacuum. The disc would spin forever once given that initial spin because there would be no losses due to friction from air resistance.

It would still stop due to internal friction within the disk itself. Same reason why the moon stopped "spinning" and now has one side that perpetually faces the earth.

 

[BruceLee]

Originally posted by: f95toli
The way we interpret the laws have in some cases changed dramatically but the mathematical formulations still holds, some "laws" like Newtons have turned out not to be valid in all situations but that does not mean that they are wrong.

This is exactly what I was getting at when I said "well maybe not wrong, but unable to answer a certain set of questions" The fact is Newton wasn't wrong, he just couldn't account for Mercury. I'm not saying that Thermodynamics has to be completely disproven one day, but what I am saying is that there more than likely will be some new theory that comes along and at least changes the way people view it. All I am saying is the way science has progressed (and will continue to progress) is by questioning current theories in light of alarming new evidence, and/or changing the way in which we view a certain scientific theory. It's not like we don't use Newtonian Mechanics anymore, it just doesnt work in some areas. This is what happens as our tools and knowledge of a certain phenomenon get "better". All I am saying is I think it would be foolish to stick by the claim that Thermodynamics will always be true or something like that.

 

[f95toli]

Of course I can not prove that you are wrong but I think you underestimate the "status" of the laws of thermodynamics. Conservation of energy is to physics what 1+1=2 is to math. I don't think we will ever find a sitation where this does not hold, there have been experiments where conservation of momentum/energy did not seem to hold, that is how the neutrino was "discovered" (it toom many decades before a neutrino was acually detected), I think that if we ever come across a situation like that again there will be a similar explanation.

 

[Armitage]

I would say that conservation of energy is no more fundamental then concept that distance & time are absolute. And look what happened to that idea.

 

[f95toli]

But distance and and time has never been absolute, that was just an interpretation (that turned out to be wrong) of known laws. There has never been a "law" or a theory saying that "time is absolute", that distance was not absolute has been known for a long time (a.k.a Galileis principle). You could of course say that it is implied in Newtons laws but as I wrote earlier they are not wrong, they are just limited to speeds <<c.

 

[sgtroyer]

The absoluteness of time and distance were so ingrained, so a priori obvious, that they didn't even need to be expressed as a law. They seemed so true it didn't even require thinking about. Every physical law implicitly assumed that time and distance were absolute. If that could be shown to be wrong, what makes you think conservation of energy is unassailable? Just because it seems right is no defense. Just because all evidence up until today supports it is no defense. There is no law so fundamental that it can't later be shown to be false.

And as I wrote earlier, Newton's Laws are wrong. Didn't you read my post?

 

[TheInvincibleMustard]

Originally posted by: f95toli
Of course I can not prove that you are wrong but I think you underestimate the "status" of the laws of thermodynamics. Conservation of energy is to physics what 1+1=2 is to math.

Just as clarification, 1+1=2 in Mathematics is an axiom, not a law. Mathematics is based on an axiomatic (ie, assumptional) approach and not a "law" approach as Physics is. There are a few basic axioms to Mathematics, which are basically just statements that say "this is the way things are, deal with it." There is absolutely nothing stopping you from creating an entirely new Mathematics system that says "1+1=3" and working out equations and theories from that. -- Part of the thing behind "New Math" is a reworking of some of the axioms that have been applied since long long ago in order to work out different theories and try to explain things differently.

I'm assuming, however, that you didn't intend to imply that Conservation of Energy is an axiom and therefore can be "thrown out" if we want to rework physics ...

Also, I'm surprised (and ashamed) that no one has quote the Great Homer Simpson in his physics glory:

And this perpetual motion machine that Lisa made ... it just keeps going faster and faster!

 

[MemberSince97]

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[Armitage]

As sgtroyer said, the absoluteness of time & distance is so fundemental that nobody really questioned it, although it is certainly assume in Newton's laws. I'm not sure how you come to say that Galileo's principle of relativity makes distance non-absolute?? Galileo's Principle simply styates that all inertial ... ie. non-accelerating frames are equivalent ... that you cannot distinguish a state of rest from that of constant velocity by way of observing mechanical experiments.

And Newton's Laws are wrong in that a physical law must hold true anywhere in the universe, under any conditions. Newton doesn't hold up at relativistic velocities. In the place and conditions we are typically concerned with it is an extrodinarily accurate approximation. But it is wrong in the strictest sense.

 

[gururu]

oceans are in perpetual motion. if you don't believe it, prove that they are not.:moon: