swansont Posted March 4, 2015 Posted March 4, 2015 Well that has to be definitely cleared up. It sounds like you think 100% of the Earth's angular momentum reduction has been transferred to the Moon. Well I'll be very surprised if it has. I await your calculation.
Robittybob1 Posted March 4, 2015 Author Posted March 4, 2015 (edited) I await your calculation. Well I have got some recent data to work from: http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Tidal_evolution This slightly faster rotation causes the Earth–Moon distance to increase at approximately 38 millimetres per year. In keeping with the conservation of angular momentum, the Earth's axial rotation is gradually slowing, and the Earth's day thus lengthens by about 23 microseconds every year (excluding glacial rebound). Both figures are valid only for the current configuration of the continents. "In keeping with the conservation of angular momentum ...." I wonder what percentage that is? I'll try and work it out soon as I can see how to do it. Edited March 4, 2015 by Robittybob1
Robittybob1 Posted March 5, 2015 Author Posted March 5, 2015 (edited) Well I have got some recent data to work from: http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Tidal_evolution "In keeping with the conservation of angular momentum ...." I wonder what percentage that is? I'll try and work it out soon as I can see how to do it. In the process of trying to discover how to do the above calculation and to attempt to explain why I think there won't be a 100% transfer of momentum from the Earth to the Moon, this is very nicely demonstrated in this short video on Lenz's Law. "Brass Pendulum and Lenz's Law" A potential difference is induced across the brass pendulum, and the current flows such that it opposes the motion of the pendulum (due to Lenz's Law).Brass is not a magnetic material, so the magnet is not slowing down by attracting the brass (as shown by the fact that the pendulum with slits in is not slowed down). However, when the pendulum with slits in is swung through the magnetic field, the eddy currents (which cause the pendulum to slow) are not so free to move within it. Thus Lenz's Law does not have as much effect; the current does not flow as much, so the motion is not opposed as much. When the brass pendulum is swung across the magnetic field the motion (the momentum is reduced rapidly.) So if we say "the momentum is conserved" it had to be in some other form other than motion of the main components, and that is where I'm struggling to find a clear answer. It is a bit like friction in a rolling car experiment, momentum will be lost (conserved) in the act of overcoming friction but it won't be noticed in the final momentum of the situation. Final situation the car will be stationary and all momentum will have been transferred to the environment in the form heated molecules. Do those heated molecules retain the original momentum? Maybe they do. But once that heat is radiated out into space it seems difficult to say it is conserved. With the magnet you can sense there will be induced currents in the brass block and its associated resistance and heat production. Does that heat conserve the original momentum? So if the motion of the Earth is what sets up the electromagnetic field and that field produces electrical currents and secondary heat, will momentum be lost to the spinning Earth, just as the brass weight did? Edited March 5, 2015 by Robittybob1
swansont Posted March 5, 2015 Posted March 5, 2015 Final situation the car will be stationary and all momentum will have been transferred to the environment in the form heated molecules. Heat is transfer of energy, not momentum.
Robittybob1 Posted March 5, 2015 Author Posted March 5, 2015 (edited) Heat is transfer of energy, not momentum. Where does the momentum of the swinging pendulum end up? Momentum being a vector quantity makes it different to a scalar quantity of energy. e.g. Is it correct to say this? 2 cars of equal weight going 200 mph in opposite directions have a total momentum of zero, even before they lose their kinetic energy in a head on collision? Edited March 5, 2015 by Robittybob1
imatfaal Posted March 5, 2015 Posted March 5, 2015 Momentum is conserved when there is no external force - in your pendulum case there are forces external to the pendulum alone or to the pendulum / magnet system forces. Angular momentum is conserved when there is no external torque.
Robittybob1 Posted March 5, 2015 Author Posted March 5, 2015 (edited) Where has it been claimed that the moon has only taken a small part of the angular momentum? (by someone other than you, that is) I can't find any post in this thread that says that. I'm beginning to think along your lines now. If the Moon displaces the IC and if that promotes the motion of the molten OC and hence the magnetic field. So there must be a resistance to the a drag which will contribute to the tidal acceleration of the Moon. So even if the magnetic effect of the Earth depends on the Moon the momentum will be transferred to the Moon. So can I do the required calculation? Is the Earth -Moon an isolated system? Momentum is conserved when there is no external force - in your pendulum case there are forces external to the pendulum alone or to the pendulum / magnet system forces. Angular momentum is conserved when there is no external torque. So if you hung the pendulum and Magnet up so it was contained in an another pendulum even though the first pendulum was dampened in its swing by the magnetic field I presume the total momentum is still present in the second suspending pendulum system. Edited March 5, 2015 by Robittybob1
swansont Posted March 5, 2015 Posted March 5, 2015 I'm beginning to think along your lines now. If the Moon displaces the IC and if that promotes the motion of the molten OC and hence the magnetic field. So there must be a resistance to the a drag which will contribute to the tidal acceleration of the Moon. So even if the magnetic effect of the Earth depends on the Moon the momentum will be transferred to the Moon. No, not so much. My line of thinking is that the magnetic field is not at all involved. Gravity (in the form of tides) explains the effect quite well.
nobox Posted March 5, 2015 Posted March 5, 2015 I speculate: The earth magnetic field is a result of convection flow of the liquid/half liquid metal core. No proof.
hypervalent_iodine Posted March 6, 2015 Posted March 6, 2015 I speculate: The earth magnetic field is a result of convection flow of the liquid/half liquid metal core. No proof. ! Moderator Note Please stay on topic and keep your speculative ideas to your own thread.
swansont Posted March 6, 2015 Posted March 6, 2015 Why speculate, anyway? That sounds like the accepted model.
nobox Posted March 6, 2015 Posted March 6, 2015 Really? My speculation coincides with accepted model???
Robittybob1 Posted March 6, 2015 Author Posted March 6, 2015 (edited) I'm going to have to find the required formulas. (Thanks to http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1164.0for the basic formula.) The inertia of rotation for a sphere is I = 2 / 5 * m * R^2 The angular momentum of a sphere is L = I * omega = I * 2 * pi() / T . The angular momentum of a sphere should be one to start with for the loss of angular momentum of the Earth will be one of the results I will need to find. The other will be something like orbital angular momentum. The radius of the orbit increases but that means the orbital period will lengthen too. Maybe Kepler's Third law will be useful. http://www.phy.duke.edu/~lee/P53/sat.pdf Kepler’s 3rd law a^3 / T2 = G * M / ( 4 * π^2 ) This shows that the ratio a3 /T2 is the same for all objects orbiting a given mass M. Thisis Kepler's 3rd law. Combining this with the formula for angular momentum: The magnitude of the angular momentum of the satellite is given byL = mrv⊥ I'll look at the situation of a circular orbit at the start. I have feeling Excel is not going to be sensitive enough to pick up these small changes over the very long distances between the Moon to the Earth. [i'll save this and edit when I find more formulas I need.] Edited March 6, 2015 by Robittybob1
imatfaal Posted March 6, 2015 Posted March 6, 2015 ... I have feeling Excel is not going to be sensitive enough to pick up these small changes over the very long distances between the Moon to the Earth. [i'll save this and edit when I find more formulas I need.] And for what seems like about the tenth time - you must account for your inaccuracies in measurement. The whole thing will be worthless without a measurement of error
swansont Posted March 6, 2015 Posted March 6, 2015 It's a little easier because the claim was that only a small fraction of the lost angular momentum went to the moon. So discrepancies of a few percent will be no big deal. We're looking for whether they're different by a few tens of percent.
imatfaal Posted March 6, 2015 Posted March 6, 2015 It's a little easier because the claim was that only a small fraction of the lost angular momentum went to the moon. So discrepancies of a few percent will be no big deal. We're looking for whether they're different by a few tens of percent. I had forgotten the disparity was that large.
Robittybob1 Posted March 6, 2015 Author Posted March 6, 2015 (edited) It's a little easier because the claim was that only a small fraction of the lost angular momentum went to the moon. So discrepancies of a few percent will be no big deal. We're looking for whether they're different by a few tens of percent. That's right, will it be in the order of 90 to 100% conserved (swansont???) or the 20 - 30% (Robittybob) figure that was in my head from somewhere in the past? But remember I have already conceded that swanson is right http://www.scienceforums.net/topic/87920-magnetic-heating-and-slowing-of-the-earths-rotation-split-from-axial-tilt-and-length-of-day/page-3#entry856145, and the calculations done by "Cambridge Guide to the Solar System" are impossible to refute. Page 195 if the following link doesn't work. https://books.google.co.nz/books?id=S4xDhVCxAQIC&pg=PA195&lpg=PA195&dq=conservation+of+angular+momentum+earth+moon+system&source=bl&ots=LDL36y9zes&sig=H826KxhGn8iWLs92eZNo6zYnlBA&hl=en&sa=X&ei=Oor5VJauFOLfmgX334G4Aw&ved=0CDQQ6AEwBDgK#v=onepage&q=conservation%20of%20angular%20momentum%20earth%20moon%20system&f=false Edited March 6, 2015 by Robittybob1
Robittybob1 Posted March 7, 2015 Author Posted March 7, 2015 The Earth has been slowing its rate of rotation ever since the Moon was formed or captured. I have seen day lengths talked about as short as 5 hours originally, and now it is 24 hours and still getting longer. More energy and momentum has been lost than ever can be accounted for going to tidally accelerate the Moon (that accounts for around 20%) so in my opinion the Earth's magnetic field could account for some of the remainder. The magnetic field is a type of electromagnet from the production of a current, currents are known to have a resistance and hence heating, heating is a form of energy loss. Well mechanical energy is converted to electrical energy and heat hence slowing the rotation of the Earth. What should I have said right from the beginning? Now I must always account for 100% of the momentum. "The Earth has been slowing its rate of rotation ever since the Moon was formed or captured. I have seen day lengths talked about as short as 5 hours originally, and now it is 24 hours and the days are still getting longer. More energy and momentum has been lost than ever can be accounted for going to tidally accelerate the Moon (that accounts for around 20% 3.3%) so in my opinion the Earth's magnetic field production could account for some of the remaining unaccounted for energy. Well mechanical energy is converted to electrical energy and the production of a magnetic field and heat as a result of electrical resistance. Hence the production of the Earth's magnetic field is contributing to the slowing of the rotation of the Earth and the acceleration of the Moon." That is still quite a powerful statement I believe.
swansont Posted March 7, 2015 Posted March 7, 2015 What should I have said right from the beginning? Now I must always account for 100% of the momentum. "The Earth has been slowing its rate of rotation ever since the Moon was formed or captured. I have seen day lengths talked about as short as 5 hours originally, and now it is 24 hours and the days are still getting longer. More energy and momentum has been lost than ever can be accounted for going to tidally accelerate the Moon (that accounts for around 20% 3.3%) so in my opinion the Earth's magnetic field production could account for some of the remaining unaccounted for energy. Well mechanical energy is converted to electrical energy and the production of a magnetic field and heat as a result of electrical resistance. Hence the production of the Earth's magnetic field is contributing to the slowing of the rotation of the Earth and the acceleration of the Moon." That is still quite a powerful statement I believe. Powerful with nothing to back it up. Have you done an accounting of the energy, of any sort? No, not that I have seen. You can't claim that the magnetic field accounts for slowing if it's not accounting for angular momentum changes, unless that angular momentum transfer is internal to the earth. Then you'd have to show that the internal part is speeding up for the outer part to be slowing down. It's still got to be conserved. All of this still relies on there being angular momentum transfer to the moon that's missing, and you haven't shown that. Further, the claim that the magnetic field contributes to the acceleration of the moon is a separate effect. The acceleration is gravitational (it's why it orbits). Is this a conjecture that there is some other effect, or are you referring to the receding of the moon? If it's the latter, how is that angular momentum being transferred magnetically?
Robittybob1 Posted March 7, 2015 Author Posted March 7, 2015 (edited) Powerful with nothing to back it up. Have you done an accounting of the energy, of any sort? No, not that I have seen. You can't claim that the magnetic field accounts for slowing if it's not accounting for angular momentum changes, unless that angular momentum transfer is internal to the earth. Then you'd have to show that the internal part is speeding up for the outer part to be slowing down. It's still got to be conserved. All of this still relies on there being angular momentum transfer to the moon that's missing, and you haven't shown that. Further, the claim that the magnetic field contributes to the acceleration of the moon is a separate effect. The acceleration is gravitational (it's why it orbits). Is this a conjecture that there is some other effect, or are you referring to the receding of the moon? If it's the latter, how is that angular momentum being transferred magnetically? It has been a while since I said it, but we did discuss how much energy it would take to start up the Earth's magnetic field, and how much would be required to keep it going (being equivalent to an electromagnet it was going to require a continuing current to maintain it.) We did mention the different rates of motion of the Inner Core (IC) and Outer Core (OC). I did mention the tidal displacement of the IC. That tidal displacement is like the tides on the surface, likewise there is this tide happening in the OC too. Cambridge proved the momentum lost by the Earth equates to the momentum gained by the Moon and it was without error, but it too did not split up the parts of the Earth and say which parts contributed how much. Now that is definitely beyond me, but the components have been shown, with that YT showing the Lenz's Law demonstrated to me how the magnetic effects will result in transfer of momentum (but this is happening internally within the Earth). Like the bike dynamo as long as it turned and there is a circuit, mechcanical energy will be turned into EM radiation. The acceleration is gravitational (it's why it orbits). Is this a conjecture that there is some other effect, or are you referring to the receding of the moon? If it's the latter, how is that angular momentum being transferred magnetically? Just to reiterate the acceleration is gravitational (agreed). I am referring to the recession of the Moon (that is what has been measured (the 38 mm/year). There is no angular momentum being transferred magnetically between the Earth and the Moon - no, it is all done via tidal acceleration, but all components of the tidal displacement have to be considered. This paper "Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration" http://arxiv.org/abs/1302.3960 (and there is a link to the PDF from there). discusses how the displacement of the IC is achieved. (reference added later) So I still stand by my hypothesis that "the production of the Earth's magnetic field is contributing to the slowing of the rotation of the Earth and the acceleration of the Moon." Edited March 7, 2015 by Robittybob1
swansont Posted March 7, 2015 Posted March 7, 2015 It has been a while since I said it, but we did discuss how much energy it would take to start up the Earth's magnetic field, and how much would be required to keep it going (being equivalent to an electromagnet it was going to require a continuing current to maintain it.) We did mention the different rates of motion of the Inner Core (IC) and Outer Core (OC). I did mention the tidal displacement of the IC. That tidal displacement is like the tides on the surface, likewise there is this tide happening in the OC too. Since the earth has been spinning for 4 billion odd years, the energy for the creation of the field is not an issue with regard to more recent events. Cambridge proved the momentum lost by the Earth equates to the momentum gained by the Moon and it was without error, but it too did not split up the parts of the Earth and say which parts contributed how much. Since the slowdown is measured by clocks, which are on the surface of the planet, I think it's safe to conclude it's the slowdown measured on the surface. Now that is definitely beyond me, but the components have been shown, with that YT showing the Lenz's Law demonstrated to me how the magnetic effects will result in transfer of momentum (but this is happening internally within the Earth). Like the bike dynamo as long as it turned and there is a circuit, mechcanical energy will be turned into EM radiation. Lenz's law requires a conductor, in order to have current flow. I'm not seeing how the moon can be involved in this. Just to reiterate the acceleration is gravitational (agreed). I am referring to the recession of the Moon (that is what has been measured (the 38 mm/year). There is no angular momentum being transferred magnetically between the Earth and the Moon - no, it is all done via tidal acceleration, but all components of the tidal displacement have to be considered. OK, then. Case closed. It's gravity, via tidal interactions, in the library. This paper "Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration" http://arxiv.org/abs/1302.3960 (and there is a link to the PDF from there). discusses how the displacement of the IC is achieved. (reference added later) So I still stand by my hypothesis that "the production of the Earth's magnetic field is contributing to the slowing of the rotation of the Earth and the acceleration of the Moon." OK, apparently not. Despite the fact that you agree that the effect is completely tidal, you immediately reiterate your claim that the magnetic field has something to do with it. Color me confused. (BTW that arxiv paper says nothing about magnetic fields) And, you still have presented no physics to back up your claim. For an effect that you agreed has no evidence that it's present.
Robittybob1 Posted March 7, 2015 Author Posted March 7, 2015 Since the earth has been spinning for 4 billion odd years, the energy for the creation of the field is not an issue with regard to more recent events. Since the slowdown is measured by clocks, which are on the surface of the planet, I think it's safe to conclude it's the slowdown measured on the surface. Lenz's law requires a conductor, in order to have current flow. I'm not seeing how the moon can be involved in this. OK, then. Case closed. It's gravity, via tidal interactions, in the library. OK, apparently not. Despite the fact that you agree that the effect is completely tidal, you immediately reiterate your claim that the magnetic field has something to do with it. Color me confused. (BTW that arxiv paper says nothing about magnetic fields) And, you still have presented no physics to back up your claim. For an effect that you agreed has no evidence that it's present. Yes the Earth has been around for a while but during that time the magnetic field has waxed and waned and flipped so I wouldn't want to say too much about its history. It may have needed restarting many times. In recent times (it has been 780,000 years since the magnetic field flipped), it has needed a current to keep the magnetic field going constantly for that long. It goes without saying that humans live on the surface of the Earth, but that slowdown in the Earth's rotation could potentially be measured from anywhere. That arxiv paper says nothing about magnetic fields but it did show it was possible for the IC to be displaced by up to 60 km and that displacement is toward the Moon. That means without a doubt there is this motion of the OC molten material that has not been described before. That is where my experimentation showed that with a displaced IC there is a side to the OC which is slightly narrowed and the other side which is widened yet the OC material has to rotate daily along with the Earth, and it was shown that the liquid was forced through the narrow side at a faster rate than the wide side. I would have like to prove that this could be a source of electrical current (if the OC material was electrically charged in some way). So the idea that this fluid motion plays a part in the production of the Earth's magnetic field was my theory, and it has been presented for discussion. It is my intention to perform some sort of experiment that demonstrates this effect but in truth that is beyond my present scope. I don't have the facilities or the resources, so the idea is open to be picked up by someone else.
swansont Posted March 7, 2015 Posted March 7, 2015 Yes the Earth has been around for a while but during that time the magnetic field has waxed and waned and flipped so I wouldn't want to say too much about its history. It may have needed restarting many times. In recent times (it has been 780,000 years since the magnetic field flipped), it has needed a current to keep the magnetic field going constantly for that long. The current is there because of heat-driven convection. Also safe to say the core has been hotter than the mantle for a long time. (because thermodynamics) It goes without saying that humans live on the surface of the Earth, but that slowdown in the Earth's rotation could potentially be measured from anywhere. Really? Potentially anywhere? Can you name a single place a human has been on earth that doesn't rotate at the same rate as the surface? How can you expect anyone to take such a claim seriously? That arxiv paper says nothing about magnetic fields but it did show it was possible for the IC to be displaced by up to 60 km and that displacement is toward the Moon. That means without a doubt there is this motion of the OC molten material that has not been described before. That is where my experimentation showed that with a displaced IC there is a side to the OC which is slightly narrowed and the other side which is widened yet the OC material has to rotate daily along with the Earth, and it was shown that the liquid was forced through the narrow side at a faster rate than the wide side. I would have like to prove that this could be a source of electrical current (if the OC material was electrically charged in some way). So the idea that this fluid motion plays a part in the production of the Earth's magnetic field was my theory, and it has been presented for discussion. It is my intention to perform some sort of experiment that demonstrates this effect but in truth that is beyond my present scope. I don't have the facilities or the resources, so the idea is open to be picked up by someone else. Your conjecture. With no connection to the slowing of the earth, and no physics to back that up.
Robittybob1 Posted March 8, 2015 Author Posted March 8, 2015 (edited) The current is there because of heat-driven convection. Also safe to say the core has been hotter than the mantle for a long time. (because thermodynamics) Really? Potentially anywhere? Can you name a single place a human has been on earth that doesn't rotate at the same rate as the surface? How can you expect anyone to take such a claim seriously? Your conjecture. With no connection to the slowing of the earth, and no physics to back that up. Why I don't accept heat driven convection as the most probable cause is that convection would have equal amounts of material going up as down (whatever opposite direction you decide. So if the up current tended to produce a south pole wouldn't the down part of the same convection loop negate that? Can you prove that it is "heat-driven convection"? By "anywhere" I mean if the measurements were taken anywhere in the Solar System (it didn't have to be measured from the Earth's surface. Time will tell whether this idea is correct. I don't have to prove the conjecture myself but I'm certainly keen to support any exploration into it. ..... Your conjecture. With no connection to the slowing of the earth, and no physics to back that up. Did you accept the math of the paper? ("Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration" http://arxiv.org/abs/1302.3960) For if you did, noting the Earth is spinning on its axis every 24 hours but the Moon only orbits the Earth approximately once a month, the physics of the fluid flow around that displaced IC needs to be analysed. Have you considered that? Edited March 8, 2015 by Robittybob1
swansont Posted March 8, 2015 Posted March 8, 2015 Why I don't accept heat driven convection as the most probable cause is that convection would have equal amounts of material going up as down (whatever opposite direction you decide. So if the up current tended to produce a south pole wouldn't the down part of the same convection loop negate that? No, for the same reason they don't cancel in a solenoid. Current loops create magnetic fields. Further, talking about creating a single pole is nonsensical — an "up current" would create field that went around in a circle, according to the right-hand rule. Have you ever actually studied this? Can you prove that it is "heat-driven convection"? Can I prove it? Nope. I'm not a geophysicist. Are there papers by scientists studying this, laying out why this is the best fit to the evidence? Absolutely. By "anywhere" I mean if the measurements were taken anywhere in the Solar System (it didn't have to be measured from the Earth's surface. How would they measure the rotation of anything other than the surface? Time will tell whether this idea is correct. I don't have to prove the conjecture myself but I'm certainly keen to support any exploration into it. If you are going to advance it here you need to move in that direction. Did you accept the math of the paper? ("Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration" http://arxiv.org/abs/1302.3960) For if you did, noting the Earth is spinning on its axis every 24 hours but the Moon only orbits the Earth approximately once a month, the physics of the fluid flow around that displaced IC needs to be analysed. Have you considered that? Nope. Not my burden of proof, it's yours. YOU need to make a physics argument to support your assertion.
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