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Author | Topic: Moons: their origin, age, & recession | |||||||||||||||||||||||||||||||||||||||||||
slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
I wanted to jump into this thread, but it so quickly became uncontrollable nonsense and awckward that I quickly gave up lol
I am tempted to start another thread on lunar recession, so we can calmly and slowly discuss it. (calypsis's thread accumulate pages at a high rate to say the least)
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined:
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Hey, I'm creationist by the way. But you can't just keep on piling things up in a thread, one after the other. You have to take the original claim of your thread (lunar recession), and you defend it. Rationally. And if it becomes unreasonable, you admit it and pass on to another line of argument.
You can't just keep on piling argument after argument one after the other. The laws of logic as well as reason were made by God, or rather in fact they are a direct result of God's self-consistent nature, and I would suggest you used them more. Less writing, more thinking.
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
I have read that talkorigins.org article about a year ago, I know the other side of the debate.
And I don't understand you explanation of it. ''Because of the complex interaction of forces, energy is being created'' .. energy being created, hey. You should maybe use better terminology The only reason why the moon is receeding is because the tide creates friction with the earth, which in turn causes the earth's rotation to slow down, and because the angular momentum must be conserved, the moon's own angular momentum increases, and this is why it is moving 'away' from the earth. In the past, the moon would have been closer to the earth, and so its gravitationnal pull on the water would have been greater, meaning there would have been greater friction between the earth and the ocean, meaning that, given the same earth then as now, the moon would have actually receded faster in the past. (see the third diagram on the lin you gave, or the diagram here:
Lunar Recession
| Answers in Genesis
)
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
This is kidn of ironic, considering the first to propose plate tectonics (or at least, that the continents moved) was a creationist ...
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
No... it just means more friction would've have been produced which means that more energy would have been transferred to the moon in the past than now. But that energy would be used to overcome the inertia of shifting it into a ever higher orbit. The lower you are to an object's center of gravity, the more energy that is required to move to a higher orbit. That's why it is harder to move 1000 feet away from the center of earth's gravity from sea level than it is to move 1000 feet away from the center of earth's gravity from 50000 miles above the earth. Which means that the closer the moon was to the earth, the faster it would need to orbit to move it to a higher orbit. Ok, I may not be able to explain it adequatly in english, but this is not the issue. What you said is of course true, but it does not apply to the moon which is in orbit. Their is no 'outward' force on the moon making it receed from the earth, in fact the absence of such a force means that it is continuously 'falling down' back on earth, but well since it is in orbit and so this is not readily apparent or intuitive. it is about the conservation of angular momentum, since the earth is loosing some, the moon must be gaining some. More angular momentum means it moves faster around the earth, whichin turn makes it have a higher orbit. Which means it has a higher orbit. I guess you could represent it as if the watr buldge is constantly 'pulling' on the moon and accelerating it. This is why the recession speed would have been greater in the past. Deyoung's calculations are correct, and his comprehension of the phenomenon is also correct (as is said in the very link you gave me). The whole issue depends on if k has been constant or not. PS If it isn't clear, I would guess cavediver could explain it better then me. I speak french and have only two months of university physics lol. He speaks english and has a PhD (I think ... ??) in physics.
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
Here's to hope you have done classical mechanics a bit, cause it'll be easier to explain. What you said is of coure true, but can't be applied this way to this problem.
This is the image from the talkorigins website. Put a coordinate axie x/y on the water buldge on top. We see that the gravitational pull (B) of the moon in the x direction (Bcos(angle)) has to be be countered by the friction force F in the opposite direction in order for the buldge to be in equilibrium. If the force B is higher (as was in the past) then the friction also must be higher for the buldge to be in equilibrium.
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
I think they do adress the possibility that k is not constant:
In this view, it is therefore ‘necessary to make an empirical adjustment for the tidal acceleration’.54 This is tantamount to saying that the proportionality constant k in equations (1) and (2) is actually variable,55 and must be adjusted to bring lunar chronology in line with that of the earth.56 The extremely speculative nature of such an adjustment was emphasized by Mignard who said, ‘even if we have sound reasons to accept a substantial reduction of the dissipation in the past, we are still lacking evidence of what the Moon’s orbit looked like 3 or 4 billion years ago’.
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
Hi slevesque - I'm sorry but I have to say this: you are far too smart to be a creationist, and you will not last long Hehe, Dr. Adequate told me something similar not so long ago. I do have to say that I sometimes feel like the 'odd man out' with my fellow creationists around here ...
Back to your diagram. The degree of acceleration on the Moon caused by the bulge is directly related to the lag angle (angle between the bulge axis NA and the Earth-Moon axis NM). The earth was spinning faster in the past, which increased the lag angle. Now, do you think that this dynamic process is addressed by DeYoung's approach? So in the past, the lag angle would have been greater, and so not only would the gravitational force B exterted by the moon on the buldge would have been greater because of the smaller distance, but it's ''x'' component would have been greater also since the angle between B and the buldge would have been smaller. The fact that the moon would have been closer also reduces this angle. All this would imply that the friction force would have had to be even greater than in the present for the buldge to remain in equilibrium. I couldn't tell you if this is adressed by DeYoung's approach though. The talkorigins.org article seems to be criticising DeYoung approach because he considers the tidal dissipation to be constant. In this regard, I guess his calculations are a bit simplistic because within the line of reasoning I did above, the friction force would have been greater and so the tidal dissipation would also have been higher. ( Unless I misunderstand the term 'tidal dissipation') The talkorigins article, however, suggests that the tidal dissipation should have been smaller in the past. They refer to Stacey's book 'physics of the earth' (1977) for this. I don't know how they arrive at this conclusion. Maybe since we know that the moon is 4Billions years old, then it means that the tidal dissipation must have been smaller in the past. Or is the buldge even in equilibrium ? I have a hard time imagining that it isn't, since it would mean it is either accelerating or decelerating, with the later been more probable I guess.
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
It comes from the same link Calypsis gave. The moon's recession and age - creation.com
You probably stopped at the equations I would guess, in which they use a constant k. This discuss a variable k further down the article.
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slevesque Member (Idle past 4670 days) Posts: 1456 Joined: |
I don't want to listen to the whole video, could you give the exact time he talks about this ?
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