Ghideon Posted July 4, 2019 Share Posted July 4, 2019 2 minutes ago, Strange said: Energy and mass are equivalent (cf. E=mc2) so moving energy is equivalent to moving mass around. Good point! A reason for these effects to be tricky to realize intuitively could be the scale difference. Additional analogy: 1: When giving a wheeled cart a hard push you feel the recoil. If the ground is slippery you will gain momentum backwards. 2: When lighting a flashlight you will not feel a recoil. But the conservation of momentum still applies, it is just that even a massive amount of photons do not posses enough momentum for you to be able to feel it in everyday life situations. And with energy instead of visible light this may be even less visible, but as @Strange states, the effect is still there. Case 1 is probably easy to compare to a rocket engine. Case 2 is less obvious. Link to comment Share on other sites More sharing options...
MPMin Posted July 5, 2019 Author Share Posted July 5, 2019 Is the problem having stored energy on the platform? What If the system was powered by solar panels? Link to comment Share on other sites More sharing options...
Ghideon Posted July 5, 2019 Share Posted July 5, 2019 (edited) 39 minutes ago, MPMin said: Is the problem having stored energy on the platform? What If the system was powered by solar panels? First, to repeat, there is no way you can beat the law of conservation of momentum. And before you post next modification or new idea, there is no way you can beat the law of conservation of momentum. That said, If the system gets external power you have another situation so to answer the solar panel question I think of two cases: A: If the system driven by the (small) pressure from the solar wind then you have an external force acting on the system. Result is propulsion (=solar sail, not reactionless drive). B: If you use the sun only to power parts of the system we can use a thought experiment. Neglect particle pressure or locate the system where the particle pressure is equal from all sides* so no external force act on the system. Gravity is neglected. Solar panels gives the system power**. If you use the power to send out particles or radiation in some way you have a "rocket", not a reactionless drive. If you use the energy internally*** there will be no force acting on the system, result is zero acceleration. *) I don't remember, is that at the terminal chock? **) This is a thought experiment, solar panels likely not very useful at this location ***) Neglecting infrared radiation from machinery, leaking radio signals or other things that could propel the system. Or making sure that any such radiation is symmetrical. Edited July 5, 2019 by Ghideon spelling Link to comment Share on other sites More sharing options...
Strange Posted July 5, 2019 Share Posted July 5, 2019 2 hours ago, Ghideon said: ***) Neglecting infrared radiation from machinery, leaking radio signals or other things that could propel the system. Or making sure that any such radiation is symmetrical. Worth noting that the "Pioneer anomaly" (an unexpected, very small acceleration of Pioneer 10 and 11) was eventually explained as a small asymmetry in thermal radiation. If I remember correctly, this had to take into account heat from the onboard nuclear battery and the electronics, as well as incident solar radiation (even at that distance). Link to comment Share on other sites More sharing options...
michel123456 Posted July 5, 2019 Share Posted July 5, 2019 On 7/3/2019 at 3:59 AM, J.C.MacSwell said: You can't change the centre of mass and energy of an isolated system with respect to it's reference frame...even temporarily. It's as simple as that. Is the universe as a whole an "isolated system" ? On 7/3/2019 at 6:04 PM, Janus said: As you make your schemes more and more complex all you are doing is making it more likely that you will lose track of all the momentum transfers along the way, something nature never does. Same question here. The universe is complicated. Link to comment Share on other sites More sharing options...
J.C.MacSwell Posted July 5, 2019 Share Posted July 5, 2019 1 hour ago, michel123456 said: Is the universe as a whole an "isolated system" ? Same question here. The universe is complicated. Presumably. It depends on how strictly you define universe. Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 Can we go back to the throwing of the rock anology: In the situation where the same rock was being thrown and rebounded back to the thrower (perfect elastics collision) but now at the same time as the rock is being thrown at the trampoline, the thrower is also able to throw another rock (exactly same mass and velocity) in the opposite direction to the other rock being thrown at the trampoline at exactly the same time; would this system be able to develop acceleration? Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 No On 7/5/2019 at 7:10 AM, Ghideon said: First, to repeat, there is no way you can beat the law of conservation of momentum. And before you post next modification or new idea, there is no way you can beat the law of conservation of momentum. Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 How does the above apply to the conservation of momentum when a rock is being thrown the other way as well? Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 16 minutes ago, MPMin said: How does the above apply to the conservation of momentum when a rock is being thrown the other way as well? Because: "there is no way you can beat the law of conservation of momentum." Or, to put it another way: "there is no way you can beat the law of conservation of momentum." Or, you could say: "there is no way you can beat the law of conservation of momentum." Momentum is conserved, no matter how many rocks you throw. You could fire a machine gun at the (bullet proof) trampoline. Or, more safely, a large piece of absorbent material. It would make no difference to the momentum of the system. The only way to change the momentum of the system is either to apply energy from outside (eg. a solar sail) or allow something to leave the system (eg. a rocket). We already know that the first rock make no difference, so we can ignore it. That just leaves the second rock. But we already know that a single rock makes no difference. So, to go back to the answer: no. Why? Because there is no way you can beat the law of conservation of momentum. Please tell me which part of that sentence you don't understand. 1 Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 1 hour ago, Strange said: We already know that the first rock make no difference, so we can ignore it. That just leaves the second rock. But we already know that a single rock makes no difference. The rock being thrown the other way leaves the system does it not? So how does it make no difference? Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 Just now, MPMin said: The rock being thrown the other way leaves the system does it not? So how does it make no difference? OK. That wasn't clear from your description. Get rid of the trampoline and the first rock. Just throw rocks out the back of the platform. The platform will move forward. This is the basic principle behind a rocket. Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 If wires can push against each other or attract each other by conducting currents, why can’t this force be used too generate propulsion? In my mind it needs to be pulsed because a continual force from the wires will simply cancel each other out. The magnetic field pulses from the from the wires will leave the system because there is no way to contain them, thus i am only concerned with the possibility of being able to generate momentum by pulsing magnetic fields against current carrying wires. It now seem that the conservation of momentum law no longer apply? Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 52 minutes ago, MPMin said: If wires can push against each other or attract each other by conducting currents, why can’t this force be used too generate propulsion? In my mind it needs to be pulsed because a continual force from the wires will simply cancel each other out. The magnetic field pulses from the from the wires will leave the system because there is no way to contain them, thus i am only concerned with the possibility of being able to generate momentum by pulsing magnetic fields against current carrying wires. It now seem that the conservation of momentum law no longer apply? As already noted, if you can get the radiation to leave the system asymmetrically then you will generate a (minute) thrust because radiation has momentum. Just shine a torch out the back, for example. (The force between two wires is irrelevant in this case; all that matters is the momentum leaving the system.) Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 27 minutes ago, Strange said: As already noted, if you can get the radiation to leave the system asymmetrically then you will generate a (minute) thrust because radiation has momentum. Just shine a torch out the back, for example. I don’t see it that way. A single wire carrying a current will emit the magnetic field in all directions from the wire thus cancelling out any movement. If there is another wire in parallel carrying a current there will be a force between the wires. In my mind, pulsing the current from one the wires prevents the connection of the magnetic field to the wire it came from thus leaving the other wire to push agains the magnetic pulse. Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 11 minutes ago, MPMin said: I don’t see it that way. ... In my mind... We have already established that carries no weight. A pair of wires may not radiate spherically, but it will still be symmetrical. And the force between the wires is irrelevant as it is entirely within the system. There seems little point carrying on with this. Because there is no way you can beat the law of conservation of momentum. Link to comment Share on other sites More sharing options...
Ghideon Posted July 7, 2019 Share Posted July 7, 2019 12 minutes ago, MPMin said: I don’t see it that way. A single wire carrying a current will emit the magnetic field in all directions from the wire thus cancelling out any movement. If there is another wire in parallel carrying a current there will be a force between the wires. In my mind, pulsing the current from one the wires prevents the connection of the magnetic field to the wire it came from thus leaving the other wire to push agains the magnetic pulse. First, to repeat, there is no way you can beat the law of conservation of momentum. And before you post next modification or new idea, there is no way you can beat the law of conservation of momentum. I have already explained about wires and radiation, your way of seeing does not match how reality behaves. Your "what about this variant of..." is already beaten by the more general principle. You would have to work on the fundamental level of physics, not some detail in magnetics/mechanics/rocks/trampolines Trying another angle. Conservation of momentum is extremely general. It's not one type of conservation of momentum for a few cases of macroscopic mechanics, another conservation of momentum for electricity/photons/particles etc. It is the same principle. Try this thought experiment*: Let's say you have come up with one case in everyday life where conservation of momentum is broken. That means objects can gain momentum without force applied. That would mean, since a very general principle is broken, that such things could happen all the time? Celestial bodies leaving the orbits. Subatomic particles leaving their atoms. Forum members and moderators spontaneously accelerating in every direction. Cars impossible to stop since they gain more momentum than acceleration provided. Such a universe seems rather chaotic and not what is observed and therefore not a very likely scenario. If conservation of momentum is wrong** it is wrong for everything, it would not be isolated to a few cables in your system. 1 hour ago, MPMin said: It now seem that the conservation of momentum law no longer apply? Note: always be very careful when defining the "system". Example: I could say to an inventor: "No your idea of space propulsion is wrong, conservation of momentum is not possible to beat, your rocket engine is a failure". Inventor "But there are fumes coming out from the back of the rocket, look!" I say: "you can't beat the conservation of momentum. The rocket's centre of mass is not accelerating." Inventor "AHA! I see! you define the rocket as the shell, fuel and exhausts! The complete system! I don't include the fumes from the engine, they leave the system." Me: "Good point! I got it wrong!" That is a different thing, the engine will work in space and your rocket will accelerate." The above case is intended to be kind of childish but intended to illustrate that this is one aspect of each and every kind of reactionless propulsion I have come across. The inventor and/or the one analysing is missing some aspect or failing to realise where boundaries are. Before posting more variants of attempts please read and analyse the responses so far. I think you might be close to that aha-moment where the conservation of momentum makes sense in the general case? Maybe you need to ask some questions about the conservation of momentum from a more general point of view, instead of wasting time on one case after another where the answer is known to be you can beat the law of conservation of momentum? *) Disclaimer: Quick post, not much time to think too deeply about the correctness of this part. **) Im not discussing universe as a whole here, I think universe was mentioned in an earlier post. For instance the accelerating increasing distances between remote galaxies is not "propulsion". On such scales "proper velocity" etc complicates the discussion too much for this thread. 1 Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 12 minutes ago, Strange said: We have already established that carries no weight. All of man’s creations started with an idea, tread carefully when assuming the authority to say any idea carries no weight. 22 minutes ago, Strange said: And the force between the wires is irrelevant as it is entirely within the system. It would seem you are still thinking of this as a closed system? I’m confident that the magnetic field radiates symmetrically outward from the wire. ‘In my mind’ i see the magnetic field travelling outward from the wire, (try to think of it in slow motion at the instant a current starts flowing through the wire, the magnetic field begins travelling outward from the wire and fills the space, I’m assuming this happens at the speed of light) where as in every worked example of current carrying wires and forces, the magnetic field already occupies the entire space. This is why I’m talking about a pulse, not a continual force. Whilst a agree when we talk about shifting mass in a closed system then the conservation of momentum applies. However, when it comes to pulsing a magnetic field I don’t see the conservation law applying because the system is not closed, a lot of the magnetic field will be lost outside the system. As the system will lose a lot of the magnetic field, the system will require an energy input and to be clear i never suggested it wouldn’t. The way i see this propulsion system working is utilising the force between the current carrying wires. No one has yet explained to me why this wont work except to say it defies Newton’s Law when i think we’ve established it doesn’t as its not a closed system. When two wires carry a continual current they push or pull against each other with equal force thus cancelling out the moving forces and no momentum. But if a magnetic field could be pulsed at the other wire, surely only one wire would move? I see only one of the wires moving because the force from the wire that pulsed the magnetic field is no longer carrying a current after the magnetic pulse leaves the wire. The other wire should still move when it pulses a current just as the other magnetic field arrives at the other wire. To be clear these events would be happing at extremely small time frames as the magnetic pulse would be travelling at the speed of light. On that note this is the only reason i see it not being a practical propulsion system because i cant imagine being able to pulse a current for such a minute amount of time. The two wires will need to be in parallel to each other, this could be achieved by having two wire rings adjacent to each other but either way as long as the wires are in parallel it should work. Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 11 minutes ago, MPMin said: All of man’s creations started with an idea, tread carefully when assuming the authority to say any idea carries no weight. All I mean is that your imagination cannot compare with actual science (ie reality). 12 minutes ago, MPMin said: However, when it comes to pulsing a magnetic field I don’t see the conservation law applying because the system is not closed, a lot of the magnetic field will be lost outside the system. As the system will lose a lot of the magnetic field, the system will require an energy input and to be clear i never suggested it wouldn’t. The electromagnetic waves you generate carry away momentum. But, because it is symmetrical, there will be no net change to the momentum of the craft. Lets say that your pulse has momentum x to the left, then the platform will gain x to the right. But because the pulse is symmetrical it will have an equal and opposite to the right; this cancels out by giving platform x to the left. It cancels out. The only way to change the momentum of the platform is to release momentum in one direction, which will give the platform momentum in the opposite direction. 21 minutes ago, MPMin said: But if a magnetic field could be pulsed at the other wire, surely only one wire would move? Irrelevant because that is internal to the system. Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 45 minutes ago, Strange said: Irrelevant because that is internal to the system. Doesn’t the combustion of a normal rocket occur internally? Please explain why this ‘internal to the system’ prevents momentum? If the system being the entire platform be it powered by solar panels or battery uses energy and loses energy through some of the magnetic field being emitted outside the system - is it still a closed system? Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 Just now, MPMin said: Doesn’t the combustion of a normal rocket occur internally? Please explain why this ‘internal to the system’ prevents momentum? Because the exhaust is ejected in one direction so the rocket moves in the opposite direction. 1 minute ago, MPMin said: If the system being the entire platform be it powered by solar panels or battery uses energy and loses energy through some of the magnetic field being emitted outside the system - is it still a closed system? This is getting stupid. You have already been told that if you emit the radiation in one direction then the platform will move in the opposite direction. Link to comment Share on other sites More sharing options...
MPMin Posted July 7, 2019 Author Share Posted July 7, 2019 4 minutes ago, Strange said: This is getting stupid. You have already been told that if you emit the radiation in one direction then the platform will move in the opposite direction. For the sake of argument, if all that’s happening by pulsing the magnetic fields is canceling out the magnetic field in the direction of the other wire leaving a net magnetic field force going the other way will it move? Link to comment Share on other sites More sharing options...
Strange Posted July 7, 2019 Share Posted July 7, 2019 8 minutes ago, MPMin said: For the sake of argument, if all that’s happening by pulsing the magnetic fields is canceling out the magnetic field in the direction of the other wire leaving a net magnetic field force going the other way will it move? It doesn’t matter how you generate the directional radiation. (But two parallel wires will not do that) Just use a fricking laser! Or put your wires inside a metal sphere with a hole on one side, so the radiation can only leave in one direction Link to comment Share on other sites More sharing options...
Ghideon Posted July 7, 2019 Share Posted July 7, 2019 51 minutes ago, MPMin said: For the sake of argument, if all that’s happening by pulsing the magnetic fields is canceling out the magnetic field in the direction of the other wire leaving a net magnetic field force going the other way will it move? Read my answer above, it already explains internal / external. It looks like yo missed it. Again: Internal forces does not generate propulsion. It doesn't matter how many cables or magnets or rocks or trampolines or batteries or particles or "pulses" you have, their interaction, internally in the system, cannot make the complete system move its center of mass or make the complete system accelerate. Period. You can't beat the general rule of conservation of momentum. But you can unintentionally fool yourself, or other forum members, by not defining the system correctly. As I said above. If you analyse the internals of a rocket (or other) there are many billions of forces or interactions. There are macroscopic parts pushing against each other (bolts, screws or other) and particles (electrons, protons, atoms ...) etc. The particles may have magnetic fields and momentum and there are forces governing their interaction. None of those internal forces, or any kind of sum or composition of such forces will have any impact on the momentum of the complete system. It doesn't matter if it is the force between an electron and the nucleus, the magnetic fields in a battery or between cables or if is molecules in a muscle moving an arm that throws a rock. Internal forces does not generate propulsion. Investors will not be interested. Hint: Try analysing your idea without using forces (if F=ma is tricky to apply). You seem to get sidestepped by the fact that a force at some time t=0 may be unbalanced and then countered by some force at some time t>0. Unbalanced forces doesn't automatically generate to propulsion. Use momentum instead. Where and how is momentum generated? Link to comment Share on other sites More sharing options...
J.C.MacSwell Posted July 7, 2019 Share Posted July 7, 2019 1 hour ago, MPMin said: Doesn’t the combustion of a normal rocket occur internally? Please explain why this ‘internal to the system’ prevents momentum? If the system being the entire platform be it powered by solar panels or battery uses energy and loses energy through some of the magnetic field being emitted outside the system - is it still a closed system? Still closed...but not an isolated system. On 7/2/2019 at 9:59 PM, J.C.MacSwell said: You can't change the centre of mass and energy of an isolated system with respect to it's reference frame...even temporarily. It's as simple as that. Conservation of momentum applies to all systems, but closed systems can be accelerated. Link to comment Share on other sites More sharing options...
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