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Just putting a few definitions out there... May seem obvious but a lot of people get tricked up.

Perpetual motion is merely 100% kinetic energy in a system recycled throughout the system. It bears little significant use (if obtainable) as it can only effectively store the same amount of energy put into the system. So it is pretty much limited to a battery. Once the energy has been removed from the system, it will cease to operate.

Perpetual anything pretty much relies on the same concept. Neither of the above, according to current physics understanding, can exist. The simplest perpetual system would be thermal energy trapped within a container that possessed insulation that worked infinitely well, such that no energy was able to be lost.

However, this is fundamentally different to systems which have an energy input, but the energy obtained is greater than the initial energy put in. These are 'overunity' based systems. Overunity systems are real. For instance, fossil fuel. Less energy is required to pump fossil fuels into a combustion system and ignite it than is seen at the output, which is why your car continues to run and supplies excess energy. These systems do not 'run forever', they merely have a source of energy of which is able to be accessed with less energy than the sum of the energy in the system.

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However, this is fundamentally different to systems which have an energy input, but the energy obtained is greater than the initial energy put in. These are 'overunity' based systems. Overunity systems are real. For instance, fossil fuel. Less energy is required to pump fossil fuels into a combustion system and ignite it than is seen at the output, which is why your car continues to run and supplies excess energy. These systems do not 'run forever', they merely have a source of energy of which is able to be accessed with less energy than the sum of the energy in the system.

I think this is a 'loose' way of describing this, though in practical terms you are right about the end result. That is, you don't need to personally put much energy - in terms of the energy required to dig up coal - to supply a lot of energy to a furnace. However, you make it sound like this energy is not put into the system. The term "over-unity" is a big problem here. Really, you get out what you put in. Some of the mass-energy of the fossil fuel is converted into energy, which ultimately becomes kinetic and heat energy. If you weigh the byproducts of combustion, the water and carbon dioxide, they will weigh slightly less than the fuel you put in. If you do it precisely enough, you will find that the sum of the heat energy and kinetic energy are equal to the lost mass energy through the famous mass-energy equivalence formula E=mc^2.

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If you weigh the byproducts of combustion, the water and carbon dioxide, they will weigh slightly less than the fuel you put in. If you do it precisely enough, you will find that the sum of the heat energy and kinetic energy are equal to the lost mass energy through the famous mass-energy equivalence formula E=mc^2.

This should not be true. Combustion breaks atomic bonds, and new ones are formed, the same atoms go in as come out though. If you burn H2 gas in oxygen, you get H2O, same principle applies to the combustion of all fuels. The formula you have mentioned is only in practice in the conversion of matter to energy, or vice versa. Said conversion can be observed in atomic bombs, or nuclear reactors.

Noodle does make it seem like less energy is placed within the system than extracted, but he is merely saying that less energy is used to extract a greater amount from the fuel inserted into the system. So long as you continuously feed fuel into the system, you continuously generate power from it (this works for all living things, and engines...) He is wrong that in the current understanding of physics, perpetual systems cannot exist, because theoretically, they can. If you have a system with little to no energy loss through friction, sound, etc, then there is a potential of the system operating perpetually. Preferably no loss.

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This should not be true. Combustion breaks atomic bonds, and new ones are formed, the same atoms go in as come out though. If you burn H2 gas in oxygen, you get H2O, same principle applies to the combustion of all fuels. The formula you have mentioned is only in practice in the conversion of matter to energy, or vice versa. Said conversion can be observed in atomic bombs, or nuclear reactors.

I know it's counterintuitive, but the concept of mass-energy equivalence runs very deep. It is called mass-energy EQUIVALENCE do to the fact that mass and energy are the same thing. While we may speak loosely of mass being CONVERTED to energy in a nuclear reaction, in reality, they are two sides of the same coin.

You are right about burning H2 in oxygen to get H20, in that the number of particles will remain the same. However, the mass of the water molecule, believe it or not, will be smaller than the sum of its parts. Using E=mc^2, this mass difference is equal to the magnitude of the binding energy of the system, and also equal to the energy released in the form of kinetic energy (including thermal energy) and light.

If you were right, then nuclear reactions couldn't happen either. When a deuteron and a triton are fused to form an alpha particle and a neutron, the actual number of protons and neutrons is the same in the initial and the final system, but the alpha particle has binding energy of higher magnitude than the original nuclei. Again, this is equal to the mass difference of the initial system and the final system, and also equal to the energy released.

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Another good example, again counterintuitive, is thermal energy. If you take an object and heat it up, it will weigh more than it did when cold. This time it is the kinetic energy of the constituent particles that adds to the mass of the object, rather than binding energy.

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I think this is a 'loose' way of describing this, though in practical terms you are right about the end result. That is, you don't need to personally put much energy - in terms of the energy required to dig up coal - to supply a lot of energy to a furnace. However, you make it sound like this energy is not put into the system. The term "over-unity" is a big problem here. Really, you get out what you put in. Some of the mass-energy of the fossil fuel is converted into energy, which ultimately becomes kinetic and heat energy. If you weigh the byproducts of combustion, the water and carbon dioxide, they will weigh slightly less than the fuel you put in. If you do it precisely enough, you will find that the sum of the heat energy and kinetic energy are equal to the lost mass energy through the famous mass-energy equivalence formula E=mc^2.

I totally agree - perhaps i miscommunicated. As you say, energy, nor mass, is created, nor destroyed, merely converted, to which I totally agree with. I define over-unity as a practical element, not a thermodynamic one, ie, systems upon which sustaining the conversion of one type of energy or form (be it mass to energy or vice versa) is fully sustainable by the system itself. It would be a direct violation of fundamental thermodynamic laws to suggest the concept of overunity in a thermodynamic respect, so yes, it's a loose/practical definition. That said, in the end, regarding this topic, we are concerned about praticality, no?

Also I was just about to prepare a typical noodle-800-page-defense to some of your statements, also the hot stuff weighs less than cold stuff, but you know, i'm totally okay with being proven wrong (rather, to be educated), and, you just did. Awesome, thanks. Perhaps I can use this as a defense as to why my yeilds in the lab are so low :lol:

Noodle does make it seem like less energy is placed within the system than extracted, but he is merely saying that less energy is used to extract a greater amount from the fuel inserted into the system. So long as you continuously feed fuel into the system, you continuously generate power from it (this works for all living things, and engines...) He is wrong that in the current understanding of physics, perpetual systems cannot exist, because theoretically, they can. If you have a system with little to no energy loss through friction, sound, etc, then there is a potential of the system operating perpetually. Preferably no loss.

Just pointing out i did say that perpetual systems bear little significant use (if obtainable) - implying that they, currently, may or may not be obtainable. They're interesting as a theorem, but currently appear impractical, and perhaps currently "impossible" other then on paper (it is easy to define a closed system with no losses, but in reality this is not achievable with our current understanding of physics or engineering)

Man, haven't been on this forum in many many years, come back and learn something pretty rad. maybe I should frequent more often.

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You didn't miscommunicate. I just thought you were being sloppy in your definitions :P People are misquoted/misrepresented all the time. How careful was Einstein about the way he phrased things, and people still misquote him to 'prove' their theories about this and that. Luckily, neither you nor I are Einstein, and no one will ever gain anything by misquoting us :lol:, but I still think it's good to be careful about the way you phrase things in a thread like this.

Edited by ballzac

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Do you study physics as a profession?

I do appreciate the smack upside the head - sloppiness is not something that should be tolerated under scientific rigor!

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You are right about burning H2 in oxygen to get H20, in that the number of particles will remain the same. However, the mass of the water molecule, believe it or not, will be smaller than the sum of its parts.

Due to what? I've just done a module on atomic bonding in physics and it contained nothing that would lead me to believe that mass is not conserved in the bonding of two elements. Sharing electrons doesn't make them lighter, they retain their energy level. I understand what you said about mass being energy, that was an oversight, but I was under the impression that fission reactions utilized E=mc^2 because the net reaction resulted in a loss of... something. Unless that is just the breaking of the bonds within the nucleus.

EDIT: Oh, and be careful with that ballzac. H20 is not the same as H2O :P I do that frequently too.

And the hot stuff rises due to increased kinetic energy - decreases density. Less density floats. It's not because hot stuff actually contains less matter.

Edited by Sheather

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I think what is happening is that both mass and energy are conserved, but both general and special relativity indicate that mass and energy are interchangable via Einsteins equation.

Consider this, for a chemical reaction to take place, some element/molecule must change energy state, otherwise no reaction would take place. This difference in energy can be observed, and also calculated. The difference in energy can also be computed as a function of mass via E=mc^2. I'm not sure what you mean by "sharing electrons retains their energy level", because I would tend to think that depending on what type of bond, and the associated nuclei involved that the bond would contain different energy. Consider a single bond to a double or triple bond. The sigma bonds have a different energy level to pi bonds. It is entirely possible to promote sigma electrons to a pi electron state and vice versa, which change their energy level.

Regarding nuclei, a famous quote:

...the Uranium nucleus might indeed be a ginger kid, ready to divide itself... But, ...when the two drops separated they would be driven apart by electrical repulsion, about 200 MeV in all. Fortunately Lise Meitner remembered how to compute the masses of nuclei... and worked out that the two nuclei formed... would be lighter by about one-fifth the mass of a proton. Now whenever mass disappears energy is created, according to Einstein's formula E = mc2, and... the mass was just equivalent to 200 MeV; it all fitted!

So it appears that while mass and energy are conserved, they are only conserved when considering both.

Also, hot stuff rises because of a decrease in density, but it's important to consider that density is just mass per space. A decrease in density doesnt make something have less mass. According to E=mc^2, the increase in kinetic energy can be considered as mass. So while the object's density decreases, the object's mass increases.

Edited by n00dle

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^^ so based on what you guys are saying, t would be possible to design a solar panel that effectively looks like a see saw. As the substance heats it raises its mass that in turn makes the see saw un balanced. Once this happens the heavy end drops and moves the object with mass into the shade and vise versa. So the other end then raises and is in the sun gaining mass. This could happen infinitude as long as the sun continues to heat the matter on the high end of the see saw.

You follow????

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I think so, potentially.

However the amount of mass gained by increase in energy is so small that mere convective forces would probably dominate.

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Due to what? I've just done a module on atomic bonding in physics and it contained nothing that would lead me to believe that mass is not conserved in the bonding of two elements. Sharing electrons doesn't make them lighter, they retain their energy level. I understand what you said about mass being energy, that was an oversight, but I was under the impression that fission reactions utilized E=mc^2 because the net reaction resulted in a loss of... something. Unless that is just the breaking of the bonds within the nucleus.

The actual amount of mass lost in a chemical reaction is so small that it need not be even considered in chemistry, probably why it was never mentioned in your atomic bonding unit, but this is really where it comes from. E=mc^2 => m=E/c^2, therefore about 1x10^{-14} kg are lost in the production of one kilojoule. That's a really tiny amount of mass.

EDIT: Oh, and be careful with that ballzac. H20 is not the same as H2O :P I do that frequently too.

Haha, yeah, that's what I get for being a pedant. It was only a matter of time before someone picked me up on a mistake, lol.

^^ so based on what you guys are saying, t would be possible to design a solar panel that effectively looks like a see saw. As the substance heats it raises its mass that in turn makes the see saw un balanced. Once this happens the heavy end drops and moves the object with mass into the shade and vise versa. So the other end then raises and is in the sun gaining mass. This could happen infinitude as long as the sun continues to heat the matter on the high end of the see saw.

You follow????

In theory, this sounds like it would work to me. I don't know how effective it would be in practice considering the small amount of mass gain versus the mechanical losses. It would probably be much less efficient than the current cells that work on the photoelectric effect.

You would've seen those things that look like a lightbulb with a thing that rotates in the middle. It works on the principle that light has momentum. One side of each arm is white and the other black. The momentum transferred to the black side is roughly p=Nhf/c where f is the frequency of the photons, and N is the number of photons. The white side also gives off white light, so you add an extra p=Nhf_{white}/c to the amount of momentum transferred to the white side. It's a similar idea of using light to directly cause a mechanical change, but relies on a different principle.

On the topic of E=mc^2, you guys might be interested in Zitterbewegung. In relativistic quantum mechanics, an electron wavefunction has both positive and negetive energy components. This means that an electron with a substantial amount of kinetic energy is actually a superposition of an electron and a positron. The two wavefunctions interact in such a way the causes the wavefunction to oscillate at the speed of light around the particle's mean 'trajectory'. Physics is trippy shit.

It's interesting to note that the formula E=mc^2 doesn't actually crop up in that form very often. This is because it is only valid for stationary particles, and particles are rarely stationary. The correct formula is E^2=p^2c^2+m^2c^4. If the momentum p is zero, this reduces to E=mc^2. For 'massless' particles, it reduces to E=pc.

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1x10^{-14} kg are lost in the production of one kilojoule. That's a really tiny amount of mass.

And yet the mass of a proton is 1.67x10^-27 kg. It's a really, really huge amount of mass if this is in relation to simple chemical reactions. I get what you're saying with E=mc^2, but that surely isn't the only theory that operates in every reaction that produces or consumes energy.

I have a question for you. If energy is mass, and light is energy, and to accelerate any mass to the speed of light requires infinite energy, how does light travel at light speed ( c)? And how does it travel at c for all observers, despite their relative speeds? Modern physics doesn't do a lot for me, despite my minor interest in the class...

Edited by Sheather

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And yet the mass of a proton is 1.67x10^-27 kg. It's a really, really huge amount of mass if this is in relation to simple chemical reactions.

1000 Joules is the energy produced by burning about 30 microlitres of petrol. That means that ~3x10^(-8)% of the mass is lost. That's a small amount in my book.

I have a question for you. If energy is mass, and light is energy, and to accelerate any mass to the speed of light requires infinite energy, how does light travel at light speed ( c)?

This is not entirely true. An infinite amount of energy is required to accelerate a particle with REST mass to the speed of light. Light has no rest mass, so it has no such restriction.

And how does it travel at c for all observers, despite their relative speeds?

Velocity is a measure of distance per unit time. A time interval will not be constant, nor will distance, so there is nothing stopping the speed of light being constant for all observers. Here's a good explanation using the concept of a "light clock". If you want to cut to the chase, the explanation starts at about 2:20.

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^^^^ I still fell confused after what I thoght wasa pretty simple explaination.

So the light has to trvel in a zig zag motion, but what will happen to a clock that doesn't operate on light.

Same scenario. One clock on earth and one on a space ship traveling near the speed of light, only this time they are very accurate mechanical clocks. Explain now why time is different? so i have another picture other than zig zag light.

Thanks

Edited by Slybacon

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Time slows down regardless of the nature of the clock. This has been verified time and time again. The most recent experiments have shown the effects of time dilation at speeds as slow as 10 metres per second, using VERY accurate clocks.

I don't think there's a more simple explanation than the light clock, but let me try: The guy in the spaceship will see a laser beam from Earth pass him at the speed of light. That is, he will see it travel 1 metre in ~3x10^{-9} seconds. An observer on Earth will see the light beam passing the space ship very slowly, because from the reference frame on Earth, the spaceship is almost travelling at the same speed as the light beam. If time had NOT slowed down on the space ship, we would see the occupant have lunch, take a shit, and then have a smoke, all the while the light beam is slowly passing his ship. Yet from the occupant's perspective, the light beam whizzed past, and he didn't have time to blink. So this doesn't make sense.

Let's say the occupant DOES blink, and during this blink, the light beam passes his ship. On Earth, we will see his eyes close before the light beam reaches his ship, and it might take 20 minutes for the light beam to pass his ship from our perspective. After the light beam has passed, his eyes open again. From his perspective it has literally been the blink of an eye. From ours, it has been 20 minutes. Therefore, time was running more slowly for him than for us.

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^^^^ That was much better than the video, thank you. I've been wanting to wrap my head around that for a while.

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Modern physics doesn't do a lot for me, despite my minor interest in the class...

Be aware that physicists do not think any current theory is the be all and end all of physical theories. That's why they continue to search for new ones. Within its domain of validity, special relativity explains every observation. It is also very elegant. It is fair enough to question it, but if you don't have an alternative theory to propose, then it's not all that helpful. Do you have a better explanation for what is observed? Can you propose a 'better' theory that explains the null result of the Michelson-Morley experiment? Or one that explains the observed half-life of muons in the atmosphere? Or the validity of Maxwell's equations in all reference frames? Special relativity has resulted in a lot of predictions that have now been observed, such as time-dilation, so your theory would have to explain these observations too. To be of any use, it would have to be capable of new prediction. Do you have a theory that makes new predictions that you can test? If it is of any use, it would have to have a benefit over special relativity, such as being more elegant perhaps. Can you explain all observed phenomena using fewer assumptions than those used in special relativity? If the answer to any of these questions is "no", then special relativity is the best theory we have.

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Ah, I never did say that I had superior theories, nor did I say that I had all the answers. I don't need to surpass and upgrade something to hold the opinion that it is flawed(take the government for example). I never said that special relativity wasn't the best we had, just that it doesn't feel right for me. No need to attack the shit out of me for this statement. I'm sure it could be said to be true for many others also.

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flying spaghetti monster....

..just saying.

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Ah, I never did say that I had superior theories, nor did I say that I had all the answers. I don't need to surpass and upgrade something to hold the opinion that it is flawed(take the government for example). I never said that special relativity wasn't the best we had, just that it doesn't feel right for me. No need to attack the shit out of me for this statement. I'm sure it could be said to be true for many others also.

Bit touchy there?

All physical theories exist for the purpose of being practical, and I think it's weird to have something against a theory that you clearly don't understand. I'm not trying to offend you by saying that, it's just that I think if you took the time to develop a strong understanding of special relativity, you would probably see the beauty in it that most physicists see. Not a single person I know thinks it is a perfect theory, but I've never heard someone who has a strong understanding of it say they simply "don't like it". I never said you have to think the theory is attractive, I'm just questioning what usefulness a 'dislike' of a theory is if you can't offer any improvement. I mean, it's not the most constructive criticism.

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I'm just questioning what usefulness a 'dislike' of a theory is if you can't offer any improvement.

Who said anything about usefulness? Since when was a dislike (or like) of just about anything "useful"? I don't like it. Big whoop. I don't like lots of shit. I bet there's a lot of stuff you don't like that you're not going to work to better too. What do I get out of trying to improve it? Years of intense research and study out of my life into a science I don't really enjoy studying, so that I can fix a bug? Sorry, that isn't going to happen, I would call that a waste, despite the potential of future generations from benefiting.

If you don't like something, must you always work to fix it? You're essentially saying it's idiocy to not like something if you can't do better, but that's a ridiculous statement. I'd think it likely that it's immensely hypocritical too. I'd rather not continue an argument about this though, so I'm going to leave it there. I will pay attention to anything you have to say though :)

PS. Sorry if I came off as "touchy" but it seemed to me that you cracked the shits with me for saying I don't like something.

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Fair enough. It's just odd to me because it's almost like you're talking about a flavour of ice-cream. I'm used to people liking or disliking theories - be it scientific, political, philosophical, or whatever - based on how much they agree or disagree with the rationale behind the theory. You're totally entitled to your opinion and I never meant to insinuate otherwise. If you have an aesthetic aversion to much of modern physics, who am I to disagree?

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