Strange Posted July 8, 2019 Posted July 8, 2019 1 hour ago, MPMin said: Once the first magnetic field is pulsed away from the wire Magnetic fields don't work like that.
MPMin Posted July 8, 2019 Author Posted July 8, 2019 3 minutes ago, Strange said: Magnetic fields don't work like that Can you please explain in more detail?
Strange Posted July 8, 2019 Posted July 8, 2019 27 minutes ago, MPMin said: Can you please explain in more detail? It would involve a detailed exposition on Maxwell's equations. I am not the best person to do that. (And, I suspect, you are not the best audience for it. ) But, basically, you cannot (as far as I know) manipulate magnetic pulses using another magnetic pulse. If you were to drive the wires with an AC signal (which would generate electromagnetic waves) then you could adjust the relative phase so that interference effects control which direction most of the energy goes. This is how modern Wi-Fi works: they have multiple antennas so they can use "beam forming" to make the transmission directional. With more antennas, the more control you have over direction. With only two, it will still be symmetrical so no net thrust. https://en.wikipedia.org/wiki/Beamforming This might be a slightly better description: https://www.electronics-notes.com/articles/antennas-propagation/smart-adaptive-antennas/beamforming-beamsteering-antenna-basics.php
MPMin Posted July 8, 2019 Author Posted July 8, 2019 21 minutes ago, Strange said: But, basically, you cannot (as far as I know) manipulate magnetic pulses using another magnetic pulse. To be clear on this point, its not a collision of two magnetic fields. The magnetic pulse that arrives at the other wire acts on the wire carrying a current (and the current carrying wire acts on the magnetic pulse) If i had a better drawing program I’d colour the area of the magnetic fields. If could illustrate this better, the magnetic pulse on the right would look like a skinny doughnut and the magnetic field on the left would be completely filled in. Like this
Strange Posted July 8, 2019 Posted July 8, 2019 The force acts on the wire. It has no effect on the magnetic field generated.
MPMin Posted July 8, 2019 Author Posted July 8, 2019 I cant see the correlation between throwing a rock in every direction compared to throwing a magnetic field in every direction for this reason; when a wire carries a current (as far as I know) will only attract or repel another wire carrying a current in parallel, the wire carrying a current does not attract or repel anything else and if it did it wouldn’t be hard to make sure only non conductive materials were in the immediate vicinity of the system. The throwing the rock in every direction analogy effects everything conductive and non conductive materials. Another way to think of one cycle the magnetic pulse propulsion is to perhaps to imagine a hand grenade as the pulse. If the hand grande were to be detonated inside the vessel then yes i think I can see what you have all been trying to say. But if the hand grenade were to be detonated behind the craft it would push it in the opposite direction. What I’m proposing is that the magnetic pulse essentially occurs behind the craft because the other wire receiving the magnetic pulse acts as the back of the craft because the rest of the craft has no effect on the magnetic pulse.
Mordred Posted July 9, 2019 Posted July 9, 2019 With the magnetic field you still have a flow 9f electrons. You will also be influenced by other ionized particles in the vicinity. In other words as often mentioned your still susceptible to the conservation of momentum laws
Ghideon Posted July 9, 2019 Posted July 9, 2019 8 hours ago, MPMin said: I cant see the correlation between throwing a rock in every direction compared to throwing a magnetic field in every direction Since you started the thread asking about rocks we have used analogies and if you still do not see the connection to the cable situation we need to try a different approach without any rocks or rockets. Ok? The problem may be that we lack a common model for the magnetics and cable interaction, the sketches and general statements lacks the details needed to communicate any issues. Shall we move on and just look at the magnetic idea only? I think a few simplifications can be made so we do not need to use the full set of Maxwell’s equations. I can only think of two alternative concepts to start with: “static” or “transient”. Static, in its simplest case, is Ampere's force law*. Other basic cases are a electromagnets or electric transformers. Transients (electromagnetic pulse**) would be things radar pulses or solar flares etc. Exactly how the puls behaves or what it consists of is not yet important, I will address that in follow ups. The important thing is that in a transient case there is no time for the system to “settle”, the distance and time of travel (at speed c) between parts affects the outcome. Since you switch of the current in the first cable before the signal has reached second cable a model would need be based on transients. Would this work as a method? If so I’ll try to suggest a very simplified model. *) https://en.wikipedia.org/wiki/Amp%C3%A8re%27s_force_law#Special_case:_Two_straight_parallel_wires **)https://en.wikipedia.org/wiki/Electromagnetic_pulse
Strange Posted July 9, 2019 Posted July 9, 2019 There are three issues that need to be addressed in this whole thing: 1. Conservation of momentum. I thought you had got this, but it appears not. 2. Generating a directional pulse (And, related to that, whether it is even possible to have a directional magnetic pulse) 3. Whether a magnetic pulse would be more efficient than electric or electromagnetic. So ... 1. 9 hours ago, MPMin said: I cant see the correlation between throwing a rock in every direction compared to throwing a magnetic field in every direction for this reason; when a wire carries a current (as far as I know) will only attract or repel another wire carrying a current in parallel, the wire carrying a current does not attract or repel anything else and if it did it wouldn’t be hard to make sure only non conductive materials were in the immediate vicinity of the system. The throwing the rock in every direction analogy effects everything conductive and non conductive materials. So, I thought you had got the whole "conservation of momentum" thing. This makes me doubt it. The fact that two wires in the system have a force between them or not is irrelevant. The only thing that matters is whether you generate a pulse heading in one direction, which will impart momentum to the rest of the system in the opposite direction. So, if your pair of wires radiates symmetrically (which it will, even if not spherically symmetrical) then this is equivalent to throwing rocks in all directions. It doesn't matter if half the rocks are bounced off trampolines, nor does it matter if there are forces between the wires that generate the magnetic field. 2. 9 hours ago, MPMin said: Another way to think of one cycle the magnetic pulse propulsion is to perhaps to imagine a hand grenade as the pulse. If the hand grande were to be detonated inside the vessel then yes i think I can see what you have all been trying to say. But if the hand grenade were to be detonated behind the craft it would push it in the opposite direction. What I’m proposing is that the magnetic pulse essentially occurs behind the craft because the other wire receiving the magnetic pulse acts as the back of the craft because the rest of the craft has no effect on the magnetic pulse. The reason the grenade outside the craft will push it is because some of the blast will hit the craft and either be absorbed or reflected; this will impart momentum to the craft. In an alternative view where the grenade is still attached to the craft and explodes, then momentum is imparted to the craft because most of the blast material goes away from the craft and a small amount is blocked/shadows by the craft; resulting in a net momentum of debris in one direction, hence imparting momentum to the craft in the opposite direction. You could also do this with the grenade in the craft by allowing the blast to only escape in one direction. Kind of like a ... rocket. Now, you need to arrange for your electromagnetic pulse to be similarly directed. For example, one wire/coil generating pulses and a reflective surface (perhaps a parabolic reflector) behind it. This will ensure you get an asymmetric impulse which will therefore impart momentum to the craft. (This would be like a light sail pushed by a laser on the craft.) You cannot achieve this with two wires. 3. If we assume the same level of efficiency for whatever system you make, then there is no reason that a magnetic pulse will be more efficient than an electric or electromagnetic pulse. This is because of another conservation law: energy. If you put, say, 1 joule into generating a magnetic pulse and one joule into an electromagnetic pulse (if these things are even different, once you start talking about radiating the energy) then the pulse contains one joule. The energy carried by the pulse, and therefore the momentum carried by the pulse, is the same in both cases. Magntism is not magic. It won't give you free energy or extra momentum. 2
swansont Posted July 9, 2019 Posted July 9, 2019 Momentum is conserved as long as there is not net external force on the system. As long as you have only internal forces, momentum stays the same. Rockets move because mass is ejected with some velocity. We define the exhaust to be outside the system. Symmetric ejection gives no net force, because these are vectors and they add to zero. 10 hours ago, MPMin said: What I’m proposing is that the magnetic pulse essentially occurs behind the craft because the other wire receiving the magnetic pulse acts as the back of the craft because the rest of the craft has no effect on the magnetic pulse. If it's not part of the craft, then you need two systems, repelling each other. One could speed up while the other slows down. If it's traveling with the craft, you can't analyze it this way. It's not exerting an external force.
MPMin Posted July 9, 2019 Author Posted July 9, 2019 Just want to clear up a point here, Is there a confusion between magnetic fields and electromagnetic radiation? I’m talking about a magnetic field that’s generated by an electric current through a wire, I believe this is not an electromagnetic radiation such a light from a laser, I believe these things to be different from each other. If that’s incorrect please explain. also I think where I’m getting caught up in the conservation of momentum issue is I can’t understand how a magnetic field completely obeys the rules of conservation of momentum when a magnetic field can pass through non conductive materials that have inertia but not affect their momentum? It would seem that a magnetic field for all intensive purposes can virtually ignore non conductive materials and still effect another magnet through the material. This is why I’m struggling to understand how the conservation of momentum applies to magnetic fields in because the magnetic field in the scenario I described is only working against the other magnetic field created by the other wire while ignoring all other parts of the craft or platform or rocket etc. Further more, when the current ceases in the wire the magnetic field is free from the wire much like an explosion from a hand grenade (as described earlier) except where an explosion effects all substances with inertia, a magnetic field doesn’t affect a substance unless the substance is a conductor.
Ghideon Posted July 9, 2019 Posted July 9, 2019 (edited) 1 hour ago, Strange said: So, I thought you had got the whole "conservation of momentum" thing. This makes me doubt it. I realize that this answer is much better than mine! I suggest we put my idea on hold until @Strange ’s post is addressed; my attempt at a model would be based on, and require the reader to understand, conservation of momentum. (And maybe the model of EMP is better handled in a separate thread). 1 hour ago, Strange said: In an alternative view where the grenade is still attached to the craft and explodes, Excellent! This is by the way what i tried, and failed, to show with my rocket contraption with many engines. Edited July 9, 2019 by Ghideon Xpost with MPMin. grammar & Spelling
Strange Posted July 9, 2019 Posted July 9, 2019 Just now, MPMin said: Just want to clear up a point here, Is there a confusion between magnetic fields and electromagnetic radiation? I’m talking about a magnetic field that’s generated by an electric current through a wire, I believe this is not an electromagnetic radiation If it is a changing magnetic field, then it will generate electromagnetic radiation. I may be wrong, but I *think* that an electromagnetic wave is the only way to radiate energy (or momentum); not an isolated magnetic pulse. 2 minutes ago, MPMin said: also I think where I’m getting caught up in the conservation of momentum issue is I can’t understand how a magnetic field completely obeys the rules of conservation of momentum when a magnetic field can pass through non conductive materials that have inertia but not affect their momentum? If an object moves through a magnetic field and is affected by the magnetic field, then it will change its momentum: throw a ball bearing (or an electron) past a magnet and its path will change. In the case of, say, a sheet of plastic, the material will not interact with the magnetic field and so there will be no change in momentum. 4 minutes ago, MPMin said: This is why I’m struggling to understand how the conservation of momentum applies to magnetic fields in because the magnetic field in the scenario I described is only working against the other magnetic field created by the other wire while ignoring all other parts of the craft or platform or rocket etc. Even if magnetic fields worked like this, any interaction between the magnetic fields would also cause a reaction in the wire that generated it. For example, the first pulse approaches the second wire. That wire starts generating its magnetic field. That will be affected by the first magnetic field which will then generate a "backreaction" in the second wire. But, maybe this is why you were originally talking about throwing rocks and hitting it with another rock - you were thinking that if these things are not physically connected to the craft, how can they affect its motion? They can't. Only when they make contact (eg. when they are thrown, or when they impact a surface - at that point all the changes in momentum cancel out). The problem with the magnetic fields, is that while they are magnetic fields, they are still "attached" (causally) to the wires that generate that generate them. Once they are "free" they are no longer just magnetic fields, but electromagnetic radiation. That will carry momentum away. Unless they hit (and are absorbed/reflected) by part of the craft. 10 minutes ago, MPMin said: Further more, when the current ceases in the wire the magnetic field is free from the wire much like an explosion from a hand grenade (as described earlier) except where an explosion effects all substances with inertia, a magnetic field doesn’t affect a substance unless the substance is a conductor. Right. So you could generate your pulse inside a metal box, with one side missing. The 5 metal sides will absorb the pulse. The open side will allow it to escape. The will impart a change in momentum to the box. (Whether the pulse is generated by one wire, two wires or a coil or a magnetron or ... makes no difference)
Ghideon Posted July 9, 2019 Posted July 9, 2019 4 minutes ago, Strange said: The problem with the magnetic fields, is that while they are magnetic fields, they are still "attached" (causally) to the wires that generate that generate them. Once they are "free" they are no longer just magnetic fields, but electromagnetic radiation. That will carry momentum away. Unless they hit (and are absorbed/reflected) by part of the craft. I think the above is a better way to explain what i tried to do with words "static" vs "transient". My two cases using causality as word: 1: Causally attached = "Ampere's force law", force and equal counter force inside the structure, between cables=no propulsion. Modeled by fields or simply apply Ampere's force law directly. 2: Causally detached = momentum is carried away, modeled by particles leaving one part of a system and then leaves the system or hits another part of the system. 1 does not apply as far as I can see, not useful to model the proposed system. 2 is useful; particles moving around, obeying the conservation of momentum.
MPMin Posted July 9, 2019 Author Posted July 9, 2019 15 minutes ago, Strange said: Right. So you could generate your pulse inside a metal box, with one side missing. The 5 metal sides will absorb the pulse. The open side will allow it to escape. The will impart a change in momentum to the box. (Whether the pulse is generated by one wire, two wires or a coil or a magnetron or ... makes no difference) I thought of pulsing a magnetic field at a metal backplate on a craft - I just thought two magnetic fields would have twice the pull of one and it had the potential of having the cycle reversed allowing for twice the amount of cycles to occur thus making the system four times as powerful as pulsing a single magnetic field at a metal back plate.
swansont Posted July 9, 2019 Posted July 9, 2019 10 minutes ago, MPMin said: I thought of pulsing a magnetic field at a metal backplate on a craft - I just thought two magnetic fields would have twice the pull of one and it had the potential of having the cycle reversed allowing for twice the amount of cycles to occur thus making the system four times as powerful as pulsing a single magnetic field at a metal back plate. If it's part of the craft it's an internal force.
MPMin Posted July 9, 2019 Author Posted July 9, 2019 (edited) 1 hour ago, Ghideon said: 2 is useful; particles moving around, obeying the conservation of momentum. Are magnetic fields particles with mass, inertia or momentum? Edited July 9, 2019 by MPMin
Strange Posted July 9, 2019 Posted July 9, 2019 5 minutes ago, MPMin said: Are magnetic fields particles with mass, inertia or momentum? No. And that is part of the problem. But as your changing magnetic field will generate electromagnetic radiation which is (or can be considered to be) particles with energy and momentum, it is still possible to generate thrust. Just not in the way you are suggesting!
MPMin Posted July 9, 2019 Author Posted July 9, 2019 I think the part I’m struggling with is if a magnetic field has no mass or momentum, is it governed by the law of conservation of momentum?
Strange Posted July 9, 2019 Posted July 9, 2019 4 minutes ago, MPMin said: I think the part I’m struggling with is if a magnetic field has no mass or momentum, is it governed by the law of conservation of momentum? A static magnetic field cannot have momentum (because it is static). A changing magnetic field generates photons which carry the momentum (of the changing field). The momentum of these is conserved.
MPMin Posted July 9, 2019 Author Posted July 9, 2019 17 minutes ago, Strange said: A changing magnetic field generates photons which carry the momentum (of the changing field). The momentum of these is conserved. Are the photons of the changing magnetic field a by product?
Strange Posted July 9, 2019 Posted July 9, 2019 21 minutes ago, MPMin said: Are the photons of the changing magnetic field a by product? I'm not sure that is a meaningful question. A changing magnetic (or electric) field results in electromagnetic waves (which can also be described in terms of photons). It is not a "by product" that is just the way the fields work.
MPMin Posted July 9, 2019 Author Posted July 9, 2019 The meaning behind the question is if the photons produced are a by product how do they effect the system? Are you saying there’s no propulsion in the system because all the moment is lost to the photons instead of moving the craft?
Strange Posted July 9, 2019 Posted July 9, 2019 Just now, MPMin said: The meaning behind the question is if the photons produced are a by product how do they effect the system? Are you saying there’s no propulsion in the system because all the moment is lost to the photons instead of moving the craft? I mean you would need to emit the electromagnetic radiation (aka photons) in a specific direction to impart momentum in the opposite direction. I don't think you can generate an isolated pulse of magnetism that flies out the back of the craft to impart momentum. Because, as far as I know, there is no such thing as a "pulse of magnetic field" as a freely moving entity that can carry momentum. (And no one has told me I am mistaken yet - and that usually happens pretty quickly when I am wrong!) There is no momentum "lost" to photons; they are the only thing in your scenario that can carry momentum and hence provide thrust.
Ghideon Posted July 9, 2019 Posted July 9, 2019 3 minutes ago, MPMin said: The meaning behind the question is if the photons produced are a by product how do they effect the system? Are you saying there’s no propulsion in the system because all the moment is lost to the photons instead of moving the craft? Momentum is not "lost", momentum is conserved. By proper application of that principle you can propel things. Invalid application gives disappointing results, or leads to wrong conclusions such as belief in the possibility of reactionless drives.
Recommended Posts