Nickpr16 Posted June 5, 2015 Share Posted June 5, 2015 So I've been thinking about an idea for a motor that doesn't really need fuel. Perpetual motion machines have really gotten my mind wrapped up in a knot and i have an idea I'd like to talk to someone about. Link to comment Share on other sites More sharing options...
ajb Posted June 5, 2015 Share Posted June 5, 2015 (edited) Building a working perpetual motion machine is impossible. You cannot violate the laws of thermodynamics, nor can you actually have ideal components with no friction. I expect your idea for such a machine fails quickly, but in order to do that you need to say a bit more. I am confident other members here will point out the problems quickly. Edited June 5, 2015 by ajb Link to comment Share on other sites More sharing options...
imatfaal Posted June 5, 2015 Share Posted June 5, 2015 Physics tells us incontrovertibly that perpetual motion machines are impossible - they violate the laws of thermodynamics. As modern science is based on the laws of thermodynamics it is impossible for physics to demonstrate a viable perpetual motion machine - it would be self-contradictory Link to comment Share on other sites More sharing options...
Phi for All Posted June 5, 2015 Share Posted June 5, 2015 Perpetual motion machines have really gotten my mind wrapped up in a knot and i have an idea I'd like to talk to someone about. There is ALWAYS something you've forgotten to take into consideration. Usually friction. How feasible would it be to build a prototype of your idea? I'm going to go out on a limb here and guess it involves magnets. Link to comment Share on other sites More sharing options...
swansont Posted June 5, 2015 Share Posted June 5, 2015 Most ideas in this arena lack rigor. It's easy to make statements that violate physical law, or conflict with each other, in describing these devices. That's why the application of actual physics is required. Link to comment Share on other sites More sharing options...
TJ McCaustland Posted June 30, 2015 Share Posted June 30, 2015 I am no professional physicist but I would like to point out that perpetual motion, even if it was possible, would be useless because the moment you took force (or work from it if we want to get technical) it would lose that force and would, depending on conditions either A: stop or B: slow down significantly, and then you would have built a force battery basically, which would be useful, but sadly impractical...... It was once a dream of mine too to invent an engine that ran off perpetual motion.... then I realized it's impracticality. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 1, 2015 Share Posted July 1, 2015 So I've been thinking about an idea for a motor that doesn't really need fuel. Perpetual motion machines have really gotten my mind wrapped up in a knot and i have an idea I'd like to talk to someone about. There's a really cool reason why we can't have perpetual motion machines with a load. They put out more energy than they take in. You might be thinking, "So what, energy conservation is wrong". But here's the kicker; energy conservation, rather than being an assumption simply falls out of the general way in which the laws of physics are constructed. Without boring you with the equations themselves, the difference between potential and kinetic energy has a strict relationship to both position and momentum. From the equation that specifies this relationship, Emmy Noether was able to prove a few theorems. One of them related certain kinds of symmetry with conservation laws. Time translation symmetry just so happens to imply conservation of energy. So, if your motor worked, we would literally have to rewrite all of physics. Link to comment Share on other sites More sharing options...
fiveworlds Posted July 1, 2015 Share Posted July 1, 2015 (edited) The best perpetual motion machine I can think of is a crooke's radiometer in space. It will keep moving till the sun dies or until it brakes one or the other Edited July 1, 2015 by fiveworlds Link to comment Share on other sites More sharing options...
StringJunky Posted July 1, 2015 Share Posted July 1, 2015 (edited) I am no professional physicist but I would like to point out that perpetual motion, even if it was possible, would be useless because the moment you took force (or work from it if we want to get technical) it would lose that force and would, depending on conditions either A: stop or B: slow down significantly, and then you would have built a force battery basically, which would be useful, but sadly impractical...... It was once a dream of mine too to invent an engine that ran off perpetual motion.... then I realized it's impracticality. Yes, even if you could create a perfect 1:1 mechanical system you couldn't do any work with it without it stopping because a closed system can contain only a finite amount of useful energy. There's not just one insurmountable hurdle there's two. Edited July 1, 2015 by StringJunky Link to comment Share on other sites More sharing options...
swansont Posted July 1, 2015 Share Posted July 1, 2015 The best perpetual motion machine I can think of is a crooke's radiometer in space. It will keep moving till the sun dies or until it brakes one or the other A Crooke's radiometer isn't an example of perpetual motion (and it probably only works in atmosphere. It's not radiation pressure that drives it) Link to comment Share on other sites More sharing options...
fiveworlds Posted July 1, 2015 Share Posted July 1, 2015 It's not radiation pressure that drives it True the radiometer runs on light and heat (hot or cold). Link to comment Share on other sites More sharing options...
TJ McCaustland Posted July 1, 2015 Share Posted July 1, 2015 (edited) There's a really cool reason why we can't have perpetual motion machines with a load. They put out more energy than they take in. You might be thinking, "So what, energy conservation is wrong". But here's the kicker; energy conservation, rather than being an assumption simply falls out of the general way in which the laws of physics are constructed. Without boring you with the equations themselves, the difference between potential and kinetic energy has a strict relationship to both position and momentum. From the equation that specifies this relationship, Emmy Noether was able to prove a few theorems. One of them related certain kinds of symmetry with conservation laws. Time translation symmetry just so happens to imply conservation of energy. So, if your motor worked, we would literally have to rewrite all of physics. So don't make it work because then every physicist in the world would hate you, including me because then I have to study a whole new set of laws and models to actually think rationally or do any equations at all. Not that I'm a physicist..... YET The best perpetual motion machine I can think of is a crooke's radiometer in space. It will keep moving till the sun dies or until it brakes one or the other Oh yeah sorry fiveworlds...... the definition of perpetual motion is..... Something that can keep moving forever without any outside force acting upon it. Edited July 1, 2015 by TJ McCaustland Link to comment Share on other sites More sharing options...
JonG Posted July 1, 2015 Share Posted July 1, 2015 Actually, there is a very cool reason as to why a heat engine could be 100% efficient. All you have to do is to ensure that the low temperature side is at absolute zero which, unfortunately, can't be done. It reminds me of a restatement of the laws of thermodynamics which I once heard from someone who specialised in the area. 1st Law: You can't win, you can only break even. 2nd Law: You can only break even at absolute zero. 3rd Law: You can't get to absolute zero. 1 Link to comment Share on other sites More sharing options...
TJ McCaustland Posted July 1, 2015 Share Posted July 1, 2015 Actually, there is a very cool reason as to why a heat engine could be 100% efficient. All you have to do is to ensure that the low temperature side is at absolute zero which, unfortunately, can't be done. It reminds me of a restatement of the laws of thermodynamics which I once heard from someone who specialised in the area. 1st Law: You can't win, you can only break even. 2nd Law: You can only break even at absolute zero. 3rd Law: You can't get to absolute zero. Thermodynamics really is a pain in the back isn't it? Link to comment Share on other sites More sharing options...
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