lgl
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Post by lgl on Dec 3, 2009 12:23:28 GMT
Think of a person flying (or floating) around in a spaceshuttle. If he raises his hands, will his center of mass move closer to the ceiling? No, his feet will move down so that the center of mass remains at the same point. Now place some large mass around his feet and let him hold some large mass in his hands and make him raise and lower his hands rapidly. Will he feel something in his legs/feet?
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lgl
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Posts: 93
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Post by lgl on Dec 3, 2009 17:51:38 GMT
As promised. See how much smoother Venus' orbit is at solar minimum. We get high solar activity when it's jumping up and down, shaking the Sun. Edit: My method of showing the distance variation is flawed because it's dominated by the Ju-Sa cycle so I'm replacing it with one showing the AM variation, which is even better because it contains both speed and distance and it shows the 22 years cycle. (idea from Semi in another thread)
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Post by Graeme on Dec 3, 2009 20:31:46 GMT
Think of a person flying (or floating) around in a spaceshuttle. If he raises his hands, will his center of mass move closer to the ceiling? No, his feet will move down so that the center of mass remains at the same point. Now place some large mass around his feet and let him hold some large mass in his hands and make him raise and lower his hands rapidly. Will he feel something in his legs/feet? Okay, I'll concede my analogy on raising your hands, shifting your center of gravity, is flawed The answer to your last question is, of course, yes. But what he'll feel is the inertia of the large mass around his feet. The feet themselves won't feel any force. Two mind-experiments: #1 Consider two equal large objects (eg. double star) orbiting each other. The barycenter is half way between them and doesn't move. Now, suppose one of those two objects disappears. What happens? The barycenter moves to the center of the remaining object (as that's the center of gravity of the remaining object(s)). But, more importantly, the object heads off in a straight line. Why? Because of Newton's laws on momentum. The only reason the objects were orbiting each other is because there was a force (gravity) acting on them to prevent them from moving in a straight line. Removing that force means that the remaining object does what it wants to do -- continue moving in a straight line. What's my point? That there is NO FORCE being felt by that object to make it change it's movement. It is the (lack of) gravititational forces acting on the object that has caused the change in movement, and objects don't 'feel' gravitational forces. The link back to the original discussion is that, yes, the Sun changes its orbit as the planets move, but it is purely due to changes in the gravitational forces acting on the Sun. It is not 'forced' to move and it does not 'feel' a force. It could be argued that it is simply the laws of momentum at work. It wants to move in a straight line and is not doing so due to the gravitational effects of the planets (and other objects). As the planets move, the gravitational effects change -- it's that simple. #2 Single large object. Let's consider it stationary for the purpose of this mind experiment. The barycenter of the object(s) is the center of that object. Now, suppose another equally large object appears some distance away. What happens? The barycenter moves to half way between the two objects. Now, from the point of view of the barycenter, the appearance of the second object 'forced' the first object to move away. But that's just an illusion based on the frame of reference. From the point of view of the first object, there's no movement at all (until gravitational forces start to make the two objects move towards each other). My points? There is no 'force' that moved the first object away from the barycenter -- which is a mathematical construct corresponding to the center of gravity of the collection of objects. As for your last post, can you explain what the pink and blue bands mean? I can't see any obvious correlation between the top and bottom graphs. eg. The top graph shows a curve from 1979 to 1992, but the bottom graph (presumably sunspot counts) shows two peaks in the same period. I'll let the comment about Venus jumping up and down, shaking the Sun, slide.... ;D
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lgl
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Posts: 93
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Post by lgl on Dec 3, 2009 22:56:18 GMT
#1 Removing an object is creating a new system so that is a distraction. You haven't answered what difference it would make to the Sun whether Venus is accelerated by Jupiter or by a rocket. You explained the difference seen from Venus but that is not the question. #2 Stationary systems are not relevant here. The point is because the system orbits the galaxy it's the Sun that's moving, not the barycenter.
My graphs are supposed to show the Sun-Venus max distance and the sun spots from 1900 to 2009 and the distance jumps up and down during high solar activity, but I have now checked the 1800s and there the correlation slides so I too have to let that slide for now.
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Post by sigurdur on Dec 3, 2009 22:57:52 GMT
You are soooooo gracious............ ;D
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Post by sigurdur on Dec 3, 2009 22:59:30 GMT
When Venus jumps up and down I wake up as well....
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Post by Graeme on Dec 3, 2009 23:07:51 GMT
#1 Removing an object is creating a new system so that is a distraction. You haven't answered what difference it would make to the Sun whether Venus is accelerated by Jupiter or by a rocket. You explained the difference seen from Venus but that is not the question. Sorry, I thought it was obvious that there was no difference from the Sun's perspective. All the Sun cares about is the mass and location of the other objects as that dictates the accumulative gravitational field in which the Sun moves. And my point with that mind experiment was that the Sun wants to move in a straight line, but because of the gravitational interaction with the other objects in the solar system, it can't. But it is only being acted on by gravitational forces, and hence is still in free fall. Your original statement was that science denies that it is not in absolute free fall and I'm trying to understand what that means because as far as I can tell, it is in 'absolute free fall (depending on what meaning 'absolute' has in this context, because I don't understand what the qualifier is doing). #2 Stationary systems are not relevant here. The point is because the system orbits the galaxy it's the Sun that's moving, not the barycenter. The point of this mind experiment was to point out that a movement of the barycenter doesn't imply that there is an additional force that moves objects away from the barycenter to maintain balance, which is what your ealier posts seemed to imply. The only thing that is involved is gravity and the mathematical calculation of the new barycenter due to the movement of the objects in the solar system.
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lgl
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Post by lgl on Dec 4, 2009 8:41:13 GMT
Then my problem is that even L. Svalgaard admitted some months back that accelerating a planet by an external force would change the rotation of the Sun (or maybe it was moon/earth in that example, don't remember if that was on this board or at WUWT) and gravity from Jupiter is external to the Sun-Ve system.
#2 And my point is the barycenter can't move. It will keep it's trajectory no matter how the bodies of the system move.
Edit: "The answer to your last question is, of course, yes. But what he'll feel is the inertia of the large mass around his feet. The feet themselves won't feel any force."
Ok, replace the large mass with a bottle of water. You will create turbulence in the bottle, inertia yes. The Sun also has some inertia.
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Post by Graeme on Dec 4, 2009 22:25:37 GMT
Now we're talking about something else, and it's something I'm happy to concede. Because the Sun is not a solid object, tidal forces can have an impact. We just need someone to postulate what those tidal forces would do.
As for your comment about Jupiter and the Sun-Ve system, that's confusing the issue.
There is a barycenter between the Sun and Venus and Jupiter is not involved. If you include Jupiter, then you need to calculate a new barycenter for the combined Sun, Venus, Jupiter system, which will be different to the one for just the Sun and Venus.
In reality, the solar system's barycenter is calculated based on all the objects in the solar system, but even there it's not guaranteed to be accurate because no one knows the distribution of objects circuling the Sun outside Neptune's orbit. It is often assumed that it is uniform, but that's only an assumption and not proven.
Since the barycenter is a mathematical construct, there's no way from within the solar system to determine it's precise location empirically without knowing the details of all objects within the solar system (including objects beyond Neptune) (I'm happy to be told I'm wrong on that, by the way). However, our best attempts seems to be pretty close so they're probably good enough for all practical purposes.
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lgl
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Post by lgl on Dec 5, 2009 12:21:52 GMT
Now we're talking about something else, and it's something I'm happy to concede. Because the Sun is not a solid object, tidal forces can have an impact. We just need someone to postulate what those tidal forces would do. I don't think this is about tidal forces. They are far too weak and they would produce a 11 year cycle, not the 22 year solar cycle. In my opinion this is the core issue. You are. Like your center of mass will not move relative to the earth in a spaceshuttle just because you rearrange your mass, the SSBC will not move relative to the center of galaxy. If we could measure the distance to center of galaxy accurately we would find that the SSBC is the point with a constant distance to the center. When Jupiter is moving Venus (and Earth) the Sun must move relative to the SSBC and it will feel that motion because it was not caused by gravitational interaction between itself and the planets. Take it to the extreeme and suddenly stop Venus in its orbit. Then the Sun's motion relative to the SSBC caused by Venus will also have to stop and the Sun will of course feel this because of the hugh inertia. We will never agree on this but I think you now understand what I meant by not in free fall. Do you really think it's a coincidence that Venus' (and Earth/Moon) angular momentum cycle is in sync with the solar cycle?
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Post by Graeme on Dec 6, 2009 20:43:32 GMT
I don't think this is about tidal forces. They are far too weak and they would produce a 11 year cycle, not the 22 year solar cycle. Er... I though the solar cycle was 11 years You are. Like your center of mass will not move relative to the earth in a spaceshuttle just because you rearrange your mass, the SSBC will not move relative to the center of galaxy. If we could measure the distance to center of galaxy accurately we would find that the SSBC is the point with a constant distance to the center. Unlikely. The SSBC is more likely to be in an elliptical orbit around the galaxy's barycenter, just like the Earth/Moon barycenter is in an elliptical orbit around the Earth/Moon/Sun barycenter. Otherwise, your point is taken, though I still maintain that the barycenter is just a mathematical construct for the center of gravity of the solar system. The center of gravity of a closed system will not move due to changes within that closed system, which I think we both agree. It then gets down to what things are part of that system and what's external to it, because things that are external to it can change the location of the center of gravity, but only in respect to the center of gravity of the whole system. When Jupiter is moving Venus (and Earth) the Sun must move relative to the SSBC and it will feel that motion because it was not caused by gravitational interaction between itself and the planets. I'm afraid you'll have to prove this, because as far as I'm aware, it is purely gravitational in nature. Orbits are by their very nature based on gravitational forces. The Sun doesn't want to orbit the SSBC, it wants to move in a straight line (basic laws of momentum). What determines its orbit is the effect of gravitational forces that stop it from moving in that straight line. The movement of the planets results in a changing net gravitational force on the Sun, and that's why its orbit around the barycenter isn't a simple ellipse. Take it to the extreeme and suddenly stop Venus in its orbit. Then the Sun's motion relative to the SSBC caused by Venus will also have to stop and the Sun will of course feel this because of the hugh inertia. But you don't feel inertia. You only feel something when it tries to overcome inertia. Now Venus would feel the effects of being stopped in its orbit, but the Sun would just react to the changed net gravitational field. I thought we had agreed this earlier regarding that the Sun would not experience anything different if Venus was moved via a rocket verses it being moved by the effect of a gravitational force. We will never agree on this but I think you now understand what I meant by not in free fall. Do you really think it's a coincidence that Venus' (and Earth/Moon) angular momentum cycle is in sync with the solar cycle? I think we can agree that your definition of 'free fall' is very different from mine All you've seemed to have stated And I'm sorry, but I've never looked into angular momentum cycles so I can't comment on that. I've just seen your altered graph above and while there appears to be some correlation between the Venus AM and sun spot numbers, it's not perfect and it could be coincidence, just like the apparent size of the moon as soon from Earth is the same diameter as the Sun. That is definitely coincidence. Alternatively, it may not be coincidence, but rather both are the consequences of a common third factor and hence are not directly related. To use the same analogy that Leif used in the prior thread on this subject, there's a correlation between shoe size and intelligence for children, but that correlation is due to a third factor: age. As the children grow, their shoe size increases and their intelligence increases, but that correlation does not mean that shoe size affects intelligence, or that intelligence affects shoe size ;D There is certainly suggestive evidence that there is some sort of link between the combined gravitational effect of the planets on the Sun (as witnessed by its orbit around the SSBC) and the solar cycle, but no viable link has been discovered. Definitely a field for research, though. The first thing, however, would be to postulate what the mechanism would be, and then work out ways of testing that theory. I think that last thread on planetary theory comprehensively demolished the argument that it was the transfer of angular momentum to the Sun as the calculations demonstrated that angular momentum was being preserved. Therefore, if there really is a link, it has to be via some other mechanism. Because the Sun is not a solid object, the obvious choices are either gravitational affects changing different parts of the Sun at different rates, or magnetic effects. The problem is that both of these will have only a minor impact on the Sun, so what how do these interact to form the solar cycle? One science fiction story I read (written by a JPL scientist, from memory) postulated miniature black holes in the Sun's core. These would be affected by gravitational forces and they could definitely have an effect on what happens in the Sun's core, include how the magnetic field is generated. The mechanisms are still vague, though....
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lgl
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Post by lgl on Dec 7, 2009 12:14:47 GMT
The solar cycle is 22 years. The sun spot cycle is just the rectified solar cycle.
But you feel acceleration when it is not caused by gravity. In this case it is not because the acceleration is perpendicular to the Sun-Ve gravitational field. The Sun must accelerate but does not gain any energy from the field so it must be taken from its own rotation. The analogies of Dr. Reodore Herring are usually distractions. In this case we know that Jupiter and Earth are causing the Venus AM modulation. That discussion on conservation of AM was a dead end from the start. You need to look at how much AM the inner planets are gaining when accelerated by Jupiter. If Jupiter is not losing the same amount the Sun must compensate, resulting in altered rotation. Unfortunately I don't have the tools and skills to prove this.
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Post by Graeme on Dec 7, 2009 20:15:28 GMT
The solar cycle is 22 years. The sun spot cycle is just the rectified solar cycle. I stand corrected But you feel acceleration when it is not caused by gravity. In this case it is not because the acceleration is perpendicular to the Sun-Ve gravitational field. The Sun must accelerate but does not gain any energy from the field so it must be taken from its own rotation. The analogies of Dr. Reodore Herring are usually distractions. In this case we know that Jupiter and Earth are causing the Venus AM modulation. That discussion on conservation of AM was a dead end from the start. You need to look at how much AM the inner planets are gaining when accelerated by Jupiter. If Jupiter is not losing the same amount the Sun must compensate, resulting in altered rotation. Unfortunately I don't have the tools and skills to prove this. Unfortunately, as what you've said contradicts everything I know about orbital mechanics, you'll have to prove it if I'm to believe you. To the best of my knowledge, the Sun will not feel any acceleration because all of it's motion is determined by gravity and the laws of momentum. ie. It wants to move in a straight line and the only thing that is stopping it is the net gravitational field from the rest of the objects in the solar system. As this is, as far as I know, accepted science (and has been since around the time of Sir Isaac Newton), it is up to you to present evidence that indicates otherwise. In particular, can you provide any evidence to support your statements: and To be more precise, it is the net gravitational effect of every other object in the solar system that is causing the varying angular momentum of Venus (or any other object). And I thought that Carlson had shown in that other thread that there is no loss of angular momentum amongst the planets, and therefore, by the law of conservation of angular momentum, the Sun is not compensating by altering it's angular momentum. You can't look at the angular momentum in isolation. It has to be the complete system. Angular momentum is not necessarily conserved for individual components (as witnessed by your graph that shows the AM for Venus changing). But if you look at the vector sum of the angular moment across the whole solar system, it stays constant. I haven't tried to calculate this myself, but I accept the word of those who have. I see no reason to doubt their calculations.
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lgl
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Post by lgl on Dec 7, 2009 22:23:01 GMT
"I see no reason to doubt their calculations."
Neither do I, but AM being constant does not mean that there is not some extra AM 'transfer' as result of inter-planet perturbations. You are asking me to calculate the AM without the perturbations to compare with real world but I have no idea how to do that.
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Post by Graeme on Dec 7, 2009 22:32:15 GMT
"I see no reason to doubt their calculations." Neither do I, but AM being constant does not mean that there is not some extra AM 'transfer' as result of inter-planet perturbations. You are asking me to calculate the AM without the perturbations to compare with real world but I have no idea how to do that. But no one has been able to find such a transfer! Carlson did the calculation in that prior thread and from my understanding of what he did, he did it correctly. It showed no such transfer. I accept that you are unable to work out how to do the calculation yourself (it would take me more effort than I care to spend to try to do it myself, because I suspect I would make a few mistakes along the way), but unless someone does it and shows that there is a transfer, I'm going to continue to go with the view that there is no angular momentum transfer. What I would be more interesting in seeing is some research that starts with the assumption that the Sun is not a solid object (I think that assumption can be justified), and then look at the gravitational and magnetic effects of the planets on the different parts of the Sun to see what impact they have. eg. Do they affect the rotation at different latitudes, with a corresponding impact on the magnetic fields of the Sun (since we know that sunspots are related to magnetic fields). Yes, tidal and magentic effects are going to miniscule when looking at the Sun as a whole, but that doesn't mean that they can't have a real impact by acting as a trigger for something else. I just don't know enough to know if this is possible, or what research could be done to investigate the possibilities.
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